The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform

Lawrence E. Gilbert - One of the best experts on this subject based on the ideXlab platform.

  • Solenopsis invicta evidence for recent internal immigration across provinces in argentina
    Florida Entomologist, 2008
    Co-Authors: Patricia Julia Folgarait, Richard J W Patrock, Gloria Albionimontenegro, Luciana Saldua, Lawrence E. Gilbert
    Abstract:

    Ant tramp species refer to those with intercontinental distributions that coincide with a likely predilection for hitchhiking with human movements (Passera 1994). One such species, Solenopsis invicta Buren has been unintentionally transported across the globe from its native home in central South America over the last 70 years or more (Tschinkel 2006). Within South America it is found in a diverse set of biogeographic regions extending from its southern limit in the dry Chaco, across through the wet Mesopotamian region in Argentina and the Pampas of Uruguay and northwards through the Pantanal and other vegetational areas of Brazil (Pitts 2002). Its tramp status as well as that of others in the genus renders ‘original’ or natural distributional limits difficult to interpret, with disjunct populations of this species and others easily assigned to human transport (Trager 1991), rather than to relictual or other possible interpretations. Historical knowledge of the biogeography of the genus in many of these areas is lacking and suggests that in many cases, only molecular analyses are likely to offer resolution to competing distributional interpretations. Here we note the recent, presumably intracontinental immigration of Solenopsis invicta across provinces in Argentina. On 22 Aug 2006, while searching for Pseudacteon parasitoids of Solenopsis richteri in the Reserva Ecologica Costanera Sur (RECS) in Buenos Aires (S 34.6, W 58.3), we found 8 colonies of Solenopsis that we recognized as S. invicta . Voucher specimens were sent to James Trager who independently confirmed this diagnosis. Solenopsis invicta has never been recorded for the province (Pitts 2002) and the nearest source for the population is likely to be Rosario (ca. 250 km distant) in Santa Fe Province (Ross & Trager 1990). The fauna for the area (including that of the ants) is probably the best known for Argentina, as Buenos Aires is the demographic and academic center of the country. If a pest species such as S. invicta had been found previously it is very likely to have been recorded. RECS is built on reclaimed land from the Rio de la Plata based on a polder-system. Initial reclamation was begun in 1978 and the land was declared a natural reserve in 1985 (Faggi & Czgononi 1987). The first date suggests the earliest possible time that S. invicta could have been present in the locality. Our group was visiting the Reserva on a weekly to monthly basis from 1996 through 2001, including very thorough searches of potential hosts of Pseudacteon (Bruzzone 2004). We had failed to find S. invicta , however, which suggests an even more recent invasion. We considered the hypothesis that this population had been moved in with the large volumes of soil used in current reclamation work in the park but have determined that this material was extracted from local areas in Buenos Aires province. How S. invicta arrived here is an open question. The Reserva is a vegetated island (360 ha) abutting the Rio Plata in the middle of the hugely urbanized zone of Buenos Aires. Many plant species documented here are likely to have been swept in along the Parana, Uruguay Rivers or their tributaries (Faggi & Czgononi 1987). If the original colony(s) that founded this population had floated downstream such common vegetational flotsam might have provided necessary assistance. Buenos Aires is a major international shipping point and the ants might also have used boats as vectors. In either case, there are likely additional population fragments of S. invicta along riverfronts, though we have not yet found any. The observed population is likely to expand, given that red imported fire ant reproduction is predicted within the province by Morrison et al. (2004). Future studies examining competition between this population and surrounding S. richteri will be of interest since the dynamics might be used to reflect back on the initial confrontations between these 2 species in Alabama 70 years ago. We thank RECS for permits and UNQ for laboratory support. PJF thanks CONICET for oversight. Funding was generously supported by the Lee and Ramona Bass Foundation, the Helen C. Kleberg and Robert J. Kleberg Foundation and The State of Texas Fire Ant Project.

  • development of pseudacteon nocens diptera phoridae on Solenopsis invicta and Solenopsis richteri fire ants hymenoptera formicidae
    Journal of Economic Entomology, 2006
    Co-Authors: Patricia Julia Folgarait, Richard J W Patrock, Lawrence E. Gilbert
    Abstract:

    Abstract We studied the developmental performance of the large morph of Pseudacteon nocens Borgmeier (Diptera: Phoridae), a prospective biological control agent of imported fire ants (Hymenoptera: Formicidae). We measured selected life history traits of this parasitoid as a function of 1) host species (Solenopsis invicta Buren versus Solenopsis richteri Forel), 2) temperature (22 versus 28°C), 3) source population of the fly (Corrientes and Santiago del Estero, Argentina), and 4) varied size distributions of offered host ants. Developmental periods were influenced by host species, although the populations responded in opposing manners. Developmental times, however, were most strongly influenced by temperature with total developmental periods lengthened by 17–32% at 22°C. Pupal mortality was also significantly lower at this temperature. Although numbers of progeny per female were significantly higher for the Corrientes population, we found no significant differences in progeny per female according to host ...

  • biogeography and macroecology of phorid flies that attack fire ants in south eastern brazil and argentina
    Journal of Biogeography, 2005
    Co-Authors: Patricia Julia Folgarait, M A Pesquero, Sanford D. Porter, Octavio A Bruzzone, Lawrence E. Gilbert
    Abstract:

    Aim  Saevissima group fire ants, Solenopsis richteri and S. invicta, have become serious pests when introduced from Argentina and Brazil to other continents. In South America, Solenopsis are distributed across a great variety of habitats and climates. In North America, S. invicta, introduced free of phorids, now ranges from coast to coast in the south. Success in introducing particular Pseudacteon as agents for the biological control of fire ants has varied across climatic zones. We aimed at assembling all the information about fire ant phorids from Argentina and Brazil, to estimate their richness and geographical ranges, to perform a climatic analysis for these distributions, to define groups and climate-based communities, and to test and elucidate Rapoport's biogeographical rule. Location  Argentina and Brazil (South America). Methods  From field and museum collections and historical records, we developed a database of fire ant-specific phorids throughout their known geographical range. A total of 123 sites with values for 15 climatic variables were mapped between 10° and 38° SL and between 35° and 65° C WL for the presence/absence of phorids. We calculated species richness across all sites combined, and for each phytogeographical region, using rarefaction curves, and ICE and Mmean estimators. We calculated mid-latitudinal points, geographical ranges and areas for each species. The correlation between mid-latitudinal point and ranges/areas was tested against a null model generated from the randomization of the raw distributional data. We used several types of multivariate analyses to distinguish groups of phorids by phytogeographical regions, hosts and climate, to find gradients of climate throughout the studied area, to define phorid communities in terms of their relationships with gradients of climate, and to test a mechanism for Rapoport's rule. Results  Richness estimations using ICE and Mmean estimators were similar or higher than the observed values depending on the phytogeographical region. Cluster multivariate analyses based on climatic, phytogeographic and host data revealed distinct groupings of Pseudacton. The ‘cerrado’ group was confined to tropical savanna areas. A more ‘widespread’ group included ‘Chaco’ and ‘Maritime’ subgroups defined by their respective association with extreme temperatures or precipitation. Ordination multivariate analyses showed (1) two climatic gradients throughout the study area: one of temperature and the other of precipitation, and (2) that climatic variables significantly explained the observed assemblages of phorids. Positive and negative signs of the eigenvalues from the main axes of a canonical correspondence analysis allowed us to define eight communities whose geographical distribution resembled that of phytogeographical regions. We found a significant and positive correlation between geographical areas and mid latitudinal points, and furthermore, the Mantel test based on climatic variables suggested a mechanism for Rapoport's rule applying in the case of Pseudacteon. Main conclusions Pseudacteon species with greater mid-latitudinal points occupy broader geographical areas and confront more stressful environmental conditions. Because the composition of Pseudacteon communities is largely determined by climatic variables, the correspondence between climates at sites of origin vs. sites of release should be an important consideration in choosing specific phorids for biocontrol efforts. Resumen Metas Solenopsis richteri y S. invicta, dos miembros de las hormigas de fuego del grupo Saevissima, se han tornado serias plagas despues de ser introducidas desde Argentina/Brasil a otros continentes. En Sud America, estas especies, asi como otras Solenopsis, se encuentran distribuidas a lo largo de una gran variedad de habitats y zonas climaticas. En Norte America, S. invicta, que fue introducida sin su fauna parasitoide, ahora se distribuye de costa a costa en el Sur de ese pais. El exito de la introduccion de los foridos Pseudacteon como una estrategia de control biologico ha variado dependiendo de las zonas climaticas. Nuestro objetivo fue juntar toda la informacion sobre los foridos parasitoides de las hormigas de fuego de Argentina y Brasil, para estimar su riqueza y rangos geograficos, para realizar analisis climaticos de sus distribuciones, para definir grupos y comunidades climaticas, y para poner a prueba la regla de Rapoport y un mecanismo que la explique. Ubicacion  Argentina y Brasil (America del Sur). Metodos  Construimos una base de datos de los parasitoides especificos de las hormigas de fuego a lo largo del rango geografico conocido, a partir de datos de colectas de campo, de colecciones de museos, y de registros historicos. Ubicamos en un mapa entre los 10° y 38° LS y entre los 35° y 65° LO, los 123 sitios donde se registraron los parasitoides; en ellos ademas asignamos los valores correspondientes de 15 variables ambientales. Calculamos la riqueza para toda la region asi como para cada provincia fitogeografica, usando curvas de rarefaccion con los estimadores ICE y Mmean. Calculamos los puntos latitudinales medios, los rangos geograficos, y las areas de cada especie. La correlacion entre el punto latitudinal medio y los rangos/areas fue puesta a prueba con la generacion de un modelo nulo producto de la aleatorizacion de las especies. Usamos distintos tipos de analisis multivariados para distinguir grupos de foridos por regiones fitogeograficas, huesped y clima, para encontrar gradientes de clima a lo largo del area estudiada, para definir comunidades de foridos en relacion al clima, y para poner a prueba un mecanismo para la regla de Rapoport. Resultados  Las estimaciones de riqueza, usando ambos estimadores, fue similar o mas alta a la observada dependiendo de las provincias fitogeograficas. Los analisis de clasificacion multivariados basados en provincias fitogeograficas, huespedes y clima, revelaron distintos agrupamientos de Pseudacteon. El grupo del ‘Cerrado’ estuvo confinado a ambientes de savanas. El grupo de ‘Amplia Distribucion’ incluyo al sub-grupo del ‘Chaco’ y al ‘Maritimo’ debido a su respectiva asociacion con la temperatura y precipitacion. Los analisis multivariados de ordenamiento mostraron (1) dos gradientes climaticos en el area de estudio, uno de temperatura y otro de precipitacion, (2) que las variables climaticas explicaron significativamente el ensamble de foridos observado. Los signos, positivos y negativos, de los autovalores de los tres ejes principales del analisis de correspondencia canonica nos permitio definir ocho comunidades cuya distribucion geografica se parecia a la de las provincias fitogeograficas. Encontramos una correlacion positiva y significativa entre las areas geograficas y los puntos latitudinales medios, es mas, el Test de Mantel basado en las variables climaticas permitio identificar un mecanismo para este ensamble de Pseudacteon. Conclusiones principales  Las especies de Pseudacteon con puntos latitudinales medios mayores ocupan areas geograficas mas grandes y confrontan condiciones de stress climatico mayores. Dado que la composicion de las comunidades de Pseudacteon esta en su mayor parte determinada por variables climaticas, la correspondencia climatica entre el sitio de origen y el sitio de liberacion de los parasitoides deberia ser una consideracion importante para la seleccion de especies de foridos para el control biologico.

  • biogeography and macroecology of phorid flies that attack fire ants in south eastern brazil and argentina
    Journal of Biogeography, 2005
    Co-Authors: Patricia J. Folgarait, M A Pesquero, Sanford D. Porter, Octavio A Bruzzone, Lawrence E. Gilbert
    Abstract:

    Aim  Saevissima group fire ants, Solenopsis richteri and S. invicta, have become serious pests when introduced from Argentina and Brazil to other continents. In South America, Solenopsis are distributed across a great variety of habitats and climates. In North America, S. invicta, introduced free of phorids, now ranges from coast to coast in the south. Success in introducing particular Pseudacteon as agents for the biological control of fire ants has varied across climatic zones. We aimed at assembling all the information about fire ant phorids from Argentina and Brazil, to estimate their richness and geographical ranges, to perform a climatic analysis for these distributions, to define groups and climate-based communities, and to test and elucidate Rapoport's biogeographical rule. Location  Argentina and Brazil (South America). Methods  From field and museum collections and historical records, we developed a database of fire ant-specific phorids throughout their known geographical range. A total of 123 sites with values for 15 climatic variables were mapped between 10° and 38° SL and between 35° and 65° C WL for the presence/absence of phorids. We calculated species richness across all sites combined, and for each phytogeographical region, using rarefaction curves, and ICE and Mmean estimators. We calculated mid-latitudinal points, geographical ranges and areas for each species. The correlation between mid-latitudinal point and ranges/areas was tested against a null model generated from the randomization of the raw distributional data. We used several types of multivariate analyses to distinguish groups of phorids by phytogeographical regions, hosts and climate, to find gradients of climate throughout the studied area, to define phorid communities in terms of their relationships with gradients of climate, and to test a mechanism for Rapoport's rule. Results  Richness estimations using ICE and Mmean estimators were similar or higher than the observed values depending on the phytogeographical region. Cluster multivariate analyses based on climatic, phytogeographic and host data revealed distinct groupings of Pseudacton. The ‘cerrado’ group was confined to tropical savanna areas. A more ‘widespread’ group included ‘Chaco’ and ‘Maritime’ subgroups defined by their respective association with extreme temperatures or precipitation. Ordination multivariate analyses showed (1) two climatic gradients throughout the study area: one of temperature and the other of precipitation, and (2) that climatic variables significantly explained the observed assemblages of phorids. Positive and negative signs of the eigenvalues from the main axes of a canonical correspondence analysis allowed us to define eight communities whose geographical distribution resembled that of phytogeographical regions. We found a significant and positive correlation between geographical areas and mid latitudinal points, and furthermore, the Mantel test based on climatic variables suggested a mechanism for Rapoport's rule applying in the case of Pseudacteon. Main conclusions Pseudacteon species with greater mid-latitudinal points occupy broader geographical areas and confront more stressful environmental conditions. Because the composition of Pseudacteon communities is largely determined by climatic variables, the correspondence between climates at sites of origin vs. sites of release should be an important consideration in choosing specific phorids for biocontrol efforts. Resumen Metas Solenopsis richteri y S. invicta, dos miembros de las hormigas de fuego del grupo Saevissima, se han tornado serias plagas despues de ser introducidas desde Argentina/Brasil a otros continentes. En Sud America, estas especies, asi como otras Solenopsis, se encuentran distribuidas a lo largo de una gran variedad de habitats y zonas climaticas. En Norte America, S. invicta, que fue introducida sin su fauna parasitoide, ahora se distribuye de costa a costa en el Sur de ese pais. El exito de la introduccion de los foridos Pseudacteon como una estrategia de control biologico ha variado dependiendo de las zonas climaticas. Nuestro objetivo fue juntar toda la informacion sobre los foridos parasitoides de las hormigas de fuego de Argentina y Brasil, para estimar su riqueza y rangos geograficos, para realizar analisis climaticos de sus distribuciones, para definir grupos y comunidades climaticas, y para poner a prueba la regla de Rapoport y un mecanismo que la explique. Ubicacion  Argentina y Brasil (America del Sur). Metodos  Construimos una base de datos de los parasitoides especificos de las hormigas de fuego a lo largo del rango geografico conocido, a partir de datos de colectas de campo, de colecciones de museos, y de registros historicos. Ubicamos en un mapa entre los 10° y 38° LS y entre los 35° y 65° LO, los 123 sitios donde se registraron los parasitoides; en ellos ademas asignamos los valores correspondientes de 15 variables ambientales. Calculamos la riqueza para toda la region asi como para cada provincia fitogeografica, usando curvas de rarefaccion con los estimadores ICE y Mmean. Calculamos los puntos latitudinales medios, los rangos geograficos, y las areas de cada especie. La correlacion entre el punto latitudinal medio y los rangos/areas fue puesta a prueba con la generacion de un modelo nulo producto de la aleatorizacion de las especies. Usamos distintos tipos de analisis multivariados para distinguir grupos de foridos por regiones fitogeograficas, huesped y clima, para encontrar gradientes de clima a lo largo del area estudiada, para definir comunidades de foridos en relacion al clima, y para poner a prueba un mecanismo para la regla de Rapoport. Resultados  Las estimaciones de riqueza, usando ambos estimadores, fue similar o mas alta a la observada dependiendo de las provincias fitogeograficas. Los analisis de clasificacion multivariados basados en provincias fitogeograficas, huespedes y clima, revelaron distintos agrupamientos de Pseudacteon. El grupo del ‘Cerrado’ estuvo confinado a ambientes de savanas. El grupo de ‘Amplia Distribucion’ incluyo al sub-grupo del ‘Chaco’ y al ‘Maritimo’ debido a su respectiva asociacion con la temperatura y precipitacion. Los analisis multivariados de ordenamiento mostraron (1) dos gradientes climaticos en el area de estudio, uno de temperatura y otro de precipitacion, (2) que las variables climaticas explicaron significativamente el ensamble de foridos observado. Los signos, positivos y negativos, de los autovalores de los tres ejes principales del analisis de correspondencia canonica nos permitio definir ocho comunidades cuya distribucion geografica se parecia a la de las provincias fitogeograficas. Encontramos una correlacion positiva y significativa entre las areas geograficas y los puntos latitudinales medios, es mas, el Test de Mantel basado en las variables climaticas permitio identificar un mecanismo para este ensamble de Pseudacteon. Conclusiones principales  Las especies de Pseudacteon con puntos latitudinales medios mayores ocupan areas geograficas mas grandes y confrontan condiciones de stress climatico mayores. Dado que la composicion de las comunidades de Pseudacteon esta en su mayor parte determinada por variables climaticas, la correspondencia climatica entre el sitio de origen y el sitio de liberacion de los parasitoides deberia ser una consideracion importante para la seleccion de especies de foridos para el control biologico.

  • Rasgos morfológicos asociados a la viabilidad de pupas en parasitoides del género Pseudacteon (Diptera: Phoridae) Morphological traits associated with pupae viability in Pseudacteon (Diptera: Phoridae) parasitoids
    Sociedad Entomológica Argentina, 2005
    Co-Authors: Patricia J. Folgarait, Monica G Chirino, Lawrence E. Gilbert
    Abstract:

    RESUMEN. Fóridos del género Pseudacteon Coquillett oviponen en forrajeras del género Solenopsis Westwood y empupan en sus cabezas. Se evaluó la relación entre la viabilidad de los parasitoides, la presencia de cuernos respiratorios y el color en los opérculos de los puparios de cuatro especies de Pseudacteon criados sobre Solenopsis invicta Buren y Solenopsis richteri Forel. La presencia de cuernos respiratorios estuvo asociada a la viabilidad de las pupas para las especies consideradas (p < 0,01), pero no el color de los opérculos (p > 0,09); excepto cuando Pseudacteon cultellatus Borgmeier se desarrolló sobre hormigas de la reserva y niñeras de S. invicta (p < 0,01). Los opérculos claros predominaron en P. cultellatus; mientras que en las demás especies, que atacan a hormigas más grandes, predominaron los opérculos castaños. Debido a que los opérculos presentaron un color similar al de la hormiga parasitada, esto representaría un mimetismo por parte del parasitoide para evitar ser detectado por el huésped. Dado que los cuernos respiratorios son necesarios para la supervivencia de la mayoría de las pupas, sugerimos que sean usados como indicadores de eficiencia en los protocolos de cría. Recomendamos usar solo forrajeras dado que las otras castas no parecen ser huéspedes apropiados.ABSTRACT. Pseudacteon Coquillett phorid flies oviposit on Solenopsis Westwood ants and pupate within the ant's head. We have evaluated the relationship between pupae's viability, presence of respiratory horns and the operculum color in four species of Pseudacteon reared on Solenopsis invicta Buren and Solenopsis richteri Forel ants. The presence of respiratory horns was significantly associated with pupae's viability for all species considered (p < 0,001) but operculum color was not (p > 0,09), except (p < 0,01) when Pseudacteon cultellatus Borgmeier had developed on S. invicta nanitic and reserve workers. Pupae with light-colored opercula were more frequent in P. cultellatus, whereas brown opercula were more frequent for the other species that attack bigger ants. Mimetism can be invoked to explain the similarity in opercula color with that of the head of the parasitized ant as a way to avoid recognition by members of the colony. We conclude that the presence of respiratory horns is necessary for pupae survival of most of the pupae and we suggest to use the presence of respiratory horns as an indicator of the efficiency of rearing protocols for this group of parasitoids. We also recommend using forager ants because other casts do not seem to be appropriate hosts

Xiaofang He - One of the best experts on this subject based on the ideXlab platform.

  • comparing electroantennogram and behavioral responses of two pseudacteon phorid fly species to body extracts of black red and hybrid imported fire ants Solenopsis spp
    Journal of Insect Physiology, 2012
    Co-Authors: Samuel A Ochieng, Xiaofang He
    Abstract:

    Abstract Several phorid fly species were introduced to the southern United States for biological control of the invasive imported fire ants, Solenopsis richteri (Black), Solenopsis invicta (Red), and their Hybrid S. richteri × S. invicta (Hybrid). It has been previously reported that the Jaguariuna biotype of Pseudacteon tricuspis and the Formosan biotype of Pseudacteon curvatus could distinguish among the three fire ant species with greater preference for Hybrid and Red fire ants. We hypothesized that phorid flies might use host derived chemical cues to differentiate ant species. To determine possible differential olfactory sensitivity of phorid fly species to different fire ant species, we compared electroantennogram (EAG) and behavioral responses of both sexes of P. tricuspis and P. curvatus to body extracts of Black, Red and Hybrid fire ants. As worker sizes of Black and Hybrid fire ants used in this study were much larger than that of Red fire ant (the average weight for Black, Red and Hybrid workers was 1.707, 0.863, 1.223 mg per ants, respectively), at doses of 0.01, 0.1, 1 worker equivalent, body extracts of Black and Hybrid fire ant elicited significantly greater EAG response in both sexes of P. tricuspis than that of Red fire ant. Similarly, the EAG response in female P. curvatus to body extract of Black fire ant was significantly greater than to body extract of Red fire ant. To eliminate worker size influence on EAG response in phorid flies, we conducted a second EAG study using a dose of 1 mg ant equivalent (body extract from 1 mg of worker). No difference in EAG responses was recorded to body extract obtained from the same amount of workers among the three fire ant species (we consider viable Hybrid fire ant as a species in this paper), suggesting that worker size differences contributed to difference in EAG response in the first EAG study. In both EAG studies, male P. tricuspis showed significantly greater EAG responses than male P. curvatus to all three fire ant species. In four-way olfactometer bioassay, worker body extracts of all three fire ant species were equally attractive to P. tricuspis and P. curvatus (i.e. both phorid fly species did not show any preferences among the three fire ant species). Together, the results of the EAG and behavior studies suggest that parasitic phorid flies utilize host derived non-polar compounds from worker ants extracted out by hexane for host location but not for host preference, since both fly species are not able to distinguish among the body extracts of the three fire ant species. Future study will investigate possible involvement of polar compounds and/or non-chemical cues in mediating host preference by phorid flies.

  • comparing electroantennogram and behavioral responses of two pseudacteon phorid fly species to body extracts of black red and hybrid imported fire ants Solenopsis spp
    Journal of Insect Physiology, 2012
    Co-Authors: Samuel A Ochieng, Xiaofang He
    Abstract:

    Abstract Several phorid fly species were introduced to the southern United States for biological control of the invasive imported fire ants, Solenopsis richteri (Black), Solenopsis invicta (Red), and their Hybrid S. richteri × S. invicta (Hybrid). It has been previously reported that the Jaguariuna biotype of Pseudacteon tricuspis and the Formosan biotype of Pseudacteon curvatus could distinguish among the three fire ant species with greater preference for Hybrid and Red fire ants. We hypothesized that phorid flies might use host derived chemical cues to differentiate ant species. To determine possible differential olfactory sensitivity of phorid fly species to different fire ant species, we compared electroantennogram (EAG) and behavioral responses of both sexes of P. tricuspis and P. curvatus to body extracts of Black, Red and Hybrid fire ants. As worker sizes of Black and Hybrid fire ants used in this study were much larger than that of Red fire ant (the average weight for Black, Red and Hybrid workers was 1.707, 0.863, 1.223 mg per ants, respectively), at doses of 0.01, 0.1, 1 worker equivalent, body extracts of Black and Hybrid fire ant elicited significantly greater EAG response in both sexes of P. tricuspis than that of Red fire ant. Similarly, the EAG response in female P. curvatus to body extract of Black fire ant was significantly greater than to body extract of Red fire ant. To eliminate worker size influence on EAG response in phorid flies, we conducted a second EAG study using a dose of 1 mg ant equivalent (body extract from 1 mg of worker). No difference in EAG responses was recorded to body extract obtained from the same amount of workers among the three fire ant species (we consider viable Hybrid fire ant as a species in this paper), suggesting that worker size differences contributed to difference in EAG response in the first EAG study. In both EAG studies, male P. tricuspis showed significantly greater EAG responses than male P. curvatus to all three fire ant species. In four-way olfactometer bioassay, worker body extracts of all three fire ant species were equally attractive to P. tricuspis and P. curvatus (i.e. both phorid fly species did not show any preferences among the three fire ant species). Together, the results of the EAG and behavior studies suggest that parasitic phorid flies utilize host derived non-polar compounds from worker ants extracted out by hexane for host location but not for host preference, since both fly species are not able to distinguish among the body extracts of the three fire ant species. Future study will investigate possible involvement of polar compounds and/or non-chemical cues in mediating host preference by phorid flies.

  • host preference in pseudacteon phorid flies response of p tricuspis and p curvatus to black red and hybrid imported Solenopsis fire ants in multiple choice bioassays
    Biological Control, 2009
    Co-Authors: Xiaofang He
    Abstract:

    Abstract Host preferences in both sexes of Pseudacteon tricuspis Borgmeier (Jaguariuna biotype) and Pseudacteon curvatus Borgmeier (Formosa biotype) and their relative attraction to the imported fire ants (IFA), Solenopsis invicta Buren (red IFA), Solenopsis richteri Forel (black IFA) and S. invicta × S. richteri hybrids (hybrid IFA) were investigated in two separate experiments utilizing multiple choice flight bioassays. The results of both experiments clearly showed that both sexes of the Jaguariuna biotype of P. tricuspis could distinguish among the three IFA species and demonstrated greater preference for hybrid IFA and red IFA. This conclusion is supported by a variety of data collected on the number of fly visits, attack rate, and hovering duration (Experiment 1), and on the number of trapped flies (Experiment 2), which showed that black IFA is the least preferred of the three species. Similar results were recorded for the Formosan biotype of P. curvatus, although the data were not as strongly conclusive. Females of this biotype spent a significantly greater amount of time in hovering mode over red IFA and hybrid IFA compared to black IFA, but the other data were not significant. The red IFA is the natural host of both phorid fly biotypes and our results suggest that both biotypes may have evolved a specialized relationship with red IFA including an ability to discriminate it from related fire ants. These results are discussed in relation to the possible role of fire ant chemicals in mediating host preferences in phorid flies, contributions of male phorid flies to fire ant biocontrol, and the practical implications of the key findings.

Sanford D. Porter - One of the best experts on this subject based on the ideXlab platform.

  • host specificity and colony impacts of the fire ant pathogen Solenopsis invicta virus 3
    Journal of Invertebrate Pathology, 2013
    Co-Authors: Sanford D. Porter, Steven M. Valles
    Abstract:

    Abstract An understanding of host specificity is essential before pathogens can be used as biopesticides or self-sustaining biocontrol agents. In order to define the host range of the recently discovered Solenopsis invicta virus 3 (SINV-3), we exposed laboratory colonies of 19 species of ants in 14 genera and 4 subfamilies to this virus. Despite extreme exposure during these tests, active, replicating infections only occurred in Solenopsis invicta Buren and hybrid (S. invicta × S. richteri) fire ant colonies. The lack of infections in test Solenopsis geminata fire ants from the United States indicates that SINV-3 is restricted to the saevissima complex of South American fire ants, especially since replicating virus was also found in several field-collected samples of the black imported fire ant, Solenopsis richteri Forel. S. invicta colonies infected with SINV-3 declined dramatically with average brood reductions of 85% or more while colonies of other species exposed to virus remained uninfected and healthy. The combination of high virulence and high host specificity suggest that SINV-3 has the potential for use as either a biopesticide or a self-sustaining biocontrol agent.

  • the fire ant hymenoptera formicidae pathogen vairimorpha invictae microsporidia burenellidae not detected in florida
    Florida Entomologist, 2012
    Co-Authors: Steven M. Valles, Sanford D. Porter
    Abstract:

    Vairimorpha invictae Jouvenaz & Ellis (Micro sporidia: Burenellidae) is a microsporidian patho gen of Solenopsis fire ants in South America. Be cause Solenopsis invicta Buren fire ants infected with V. invictae were associated with higher mor tality, significantly slower colony growth, and re ductions in field populations in Argentina, there is considerable interest in utilizing this pathogen as a classical biological control agent against S. invicta in the U.S. (Briano & Williams 2002; Oi et al. 2005; Briano 2005). V. invictae was formally described by Jouvenaz & Ellis in 1986, however, it was most likely observed much earlier, being the undescribed, dimorphic microsporidium re ported from pathogen surveys conducted in Brazil in 1976 and 1979 (Jouvenaz et al., 1980; Briano & Williams 2002). Surveys for V. invictae in Ar gentina reported prevalence rates of 1, 2.3, and 10% after sampling 1836, 2528, and 2064 nests, respectively (Briano et al. 1995; 2006; Briano & Williams 2002). In the U.S., there have been surveys for vari ous fire ant pathogens since the 1970s. Limited surveys of red and black imported fire ants, S. in victa and Solenopsis richteri Forel, respectively, were conducted in northern Florida and in Mis

  • predicted range expansion of the invasive fire ant Solenopsis invicta in the eastern united states based on the vemap global warming scenario
    Diversity and Distributions, 2005
    Co-Authors: Lloyd W Morrison, Michael D Korzukhin, Sanford D. Porter
    Abstract:

    The red imported fire ant, Solenopsis invicta Buren, is an invasive pest from South America that currently occupies much of the south-eastern USA. Global warming is likely to allow range expansion of many invasive species, including S. invicta . We used a dynamic, ecophysiological model of fire ant colony growth coupled with models simulating climate change to predict the potential range expansion of S. invicta in the eastern USA over the next century. The climate change scenario predicted by the Vegetation‐Ecosystem Modelling and Analysis Project (VEMAP) was used in our analyses. Our predictions indicate that the habitable area for S. invicta may increase by c. 5% over the next 40 ‐50 years (a northward expansion of 33 ± 35 km). As the pace of global warming is expected to quicken in the latter half of the century, however, the habitable area for S. invicta in 2100 is predicted to be > 21% greater than it currently is (a northward expansion of 133 ± 68 km). Because the black imported fire ant, Solenopsis richteri Forel, occupies higher latitudes than S. invicta , the overall area of the eastern USA infested with invasive Solenopsis species could be greater than that estimated here.

  • biogeography and macroecology of phorid flies that attack fire ants in south eastern brazil and argentina
    Journal of Biogeography, 2005
    Co-Authors: Patricia Julia Folgarait, M A Pesquero, Sanford D. Porter, Octavio A Bruzzone, Lawrence E. Gilbert
    Abstract:

    Aim  Saevissima group fire ants, Solenopsis richteri and S. invicta, have become serious pests when introduced from Argentina and Brazil to other continents. In South America, Solenopsis are distributed across a great variety of habitats and climates. In North America, S. invicta, introduced free of phorids, now ranges from coast to coast in the south. Success in introducing particular Pseudacteon as agents for the biological control of fire ants has varied across climatic zones. We aimed at assembling all the information about fire ant phorids from Argentina and Brazil, to estimate their richness and geographical ranges, to perform a climatic analysis for these distributions, to define groups and climate-based communities, and to test and elucidate Rapoport's biogeographical rule. Location  Argentina and Brazil (South America). Methods  From field and museum collections and historical records, we developed a database of fire ant-specific phorids throughout their known geographical range. A total of 123 sites with values for 15 climatic variables were mapped between 10° and 38° SL and between 35° and 65° C WL for the presence/absence of phorids. We calculated species richness across all sites combined, and for each phytogeographical region, using rarefaction curves, and ICE and Mmean estimators. We calculated mid-latitudinal points, geographical ranges and areas for each species. The correlation between mid-latitudinal point and ranges/areas was tested against a null model generated from the randomization of the raw distributional data. We used several types of multivariate analyses to distinguish groups of phorids by phytogeographical regions, hosts and climate, to find gradients of climate throughout the studied area, to define phorid communities in terms of their relationships with gradients of climate, and to test a mechanism for Rapoport's rule. Results  Richness estimations using ICE and Mmean estimators were similar or higher than the observed values depending on the phytogeographical region. Cluster multivariate analyses based on climatic, phytogeographic and host data revealed distinct groupings of Pseudacton. The ‘cerrado’ group was confined to tropical savanna areas. A more ‘widespread’ group included ‘Chaco’ and ‘Maritime’ subgroups defined by their respective association with extreme temperatures or precipitation. Ordination multivariate analyses showed (1) two climatic gradients throughout the study area: one of temperature and the other of precipitation, and (2) that climatic variables significantly explained the observed assemblages of phorids. Positive and negative signs of the eigenvalues from the main axes of a canonical correspondence analysis allowed us to define eight communities whose geographical distribution resembled that of phytogeographical regions. We found a significant and positive correlation between geographical areas and mid latitudinal points, and furthermore, the Mantel test based on climatic variables suggested a mechanism for Rapoport's rule applying in the case of Pseudacteon. Main conclusions Pseudacteon species with greater mid-latitudinal points occupy broader geographical areas and confront more stressful environmental conditions. Because the composition of Pseudacteon communities is largely determined by climatic variables, the correspondence between climates at sites of origin vs. sites of release should be an important consideration in choosing specific phorids for biocontrol efforts. Resumen Metas Solenopsis richteri y S. invicta, dos miembros de las hormigas de fuego del grupo Saevissima, se han tornado serias plagas despues de ser introducidas desde Argentina/Brasil a otros continentes. En Sud America, estas especies, asi como otras Solenopsis, se encuentran distribuidas a lo largo de una gran variedad de habitats y zonas climaticas. En Norte America, S. invicta, que fue introducida sin su fauna parasitoide, ahora se distribuye de costa a costa en el Sur de ese pais. El exito de la introduccion de los foridos Pseudacteon como una estrategia de control biologico ha variado dependiendo de las zonas climaticas. Nuestro objetivo fue juntar toda la informacion sobre los foridos parasitoides de las hormigas de fuego de Argentina y Brasil, para estimar su riqueza y rangos geograficos, para realizar analisis climaticos de sus distribuciones, para definir grupos y comunidades climaticas, y para poner a prueba la regla de Rapoport y un mecanismo que la explique. Ubicacion  Argentina y Brasil (America del Sur). Metodos  Construimos una base de datos de los parasitoides especificos de las hormigas de fuego a lo largo del rango geografico conocido, a partir de datos de colectas de campo, de colecciones de museos, y de registros historicos. Ubicamos en un mapa entre los 10° y 38° LS y entre los 35° y 65° LO, los 123 sitios donde se registraron los parasitoides; en ellos ademas asignamos los valores correspondientes de 15 variables ambientales. Calculamos la riqueza para toda la region asi como para cada provincia fitogeografica, usando curvas de rarefaccion con los estimadores ICE y Mmean. Calculamos los puntos latitudinales medios, los rangos geograficos, y las areas de cada especie. La correlacion entre el punto latitudinal medio y los rangos/areas fue puesta a prueba con la generacion de un modelo nulo producto de la aleatorizacion de las especies. Usamos distintos tipos de analisis multivariados para distinguir grupos de foridos por regiones fitogeograficas, huesped y clima, para encontrar gradientes de clima a lo largo del area estudiada, para definir comunidades de foridos en relacion al clima, y para poner a prueba un mecanismo para la regla de Rapoport. Resultados  Las estimaciones de riqueza, usando ambos estimadores, fue similar o mas alta a la observada dependiendo de las provincias fitogeograficas. Los analisis de clasificacion multivariados basados en provincias fitogeograficas, huespedes y clima, revelaron distintos agrupamientos de Pseudacteon. El grupo del ‘Cerrado’ estuvo confinado a ambientes de savanas. El grupo de ‘Amplia Distribucion’ incluyo al sub-grupo del ‘Chaco’ y al ‘Maritimo’ debido a su respectiva asociacion con la temperatura y precipitacion. Los analisis multivariados de ordenamiento mostraron (1) dos gradientes climaticos en el area de estudio, uno de temperatura y otro de precipitacion, (2) que las variables climaticas explicaron significativamente el ensamble de foridos observado. Los signos, positivos y negativos, de los autovalores de los tres ejes principales del analisis de correspondencia canonica nos permitio definir ocho comunidades cuya distribucion geografica se parecia a la de las provincias fitogeograficas. Encontramos una correlacion positiva y significativa entre las areas geograficas y los puntos latitudinales medios, es mas, el Test de Mantel basado en las variables climaticas permitio identificar un mecanismo para este ensamble de Pseudacteon. Conclusiones principales  Las especies de Pseudacteon con puntos latitudinales medios mayores ocupan areas geograficas mas grandes y confrontan condiciones de stress climatico mayores. Dado que la composicion de las comunidades de Pseudacteon esta en su mayor parte determinada por variables climaticas, la correspondencia climatica entre el sitio de origen y el sitio de liberacion de los parasitoides deberia ser una consideracion importante para la seleccion de especies de foridos para el control biologico.

  • biogeography and macroecology of phorid flies that attack fire ants in south eastern brazil and argentina
    Journal of Biogeography, 2005
    Co-Authors: Patricia J. Folgarait, M A Pesquero, Sanford D. Porter, Octavio A Bruzzone, Lawrence E. Gilbert
    Abstract:

    Aim  Saevissima group fire ants, Solenopsis richteri and S. invicta, have become serious pests when introduced from Argentina and Brazil to other continents. In South America, Solenopsis are distributed across a great variety of habitats and climates. In North America, S. invicta, introduced free of phorids, now ranges from coast to coast in the south. Success in introducing particular Pseudacteon as agents for the biological control of fire ants has varied across climatic zones. We aimed at assembling all the information about fire ant phorids from Argentina and Brazil, to estimate their richness and geographical ranges, to perform a climatic analysis for these distributions, to define groups and climate-based communities, and to test and elucidate Rapoport's biogeographical rule. Location  Argentina and Brazil (South America). Methods  From field and museum collections and historical records, we developed a database of fire ant-specific phorids throughout their known geographical range. A total of 123 sites with values for 15 climatic variables were mapped between 10° and 38° SL and between 35° and 65° C WL for the presence/absence of phorids. We calculated species richness across all sites combined, and for each phytogeographical region, using rarefaction curves, and ICE and Mmean estimators. We calculated mid-latitudinal points, geographical ranges and areas for each species. The correlation between mid-latitudinal point and ranges/areas was tested against a null model generated from the randomization of the raw distributional data. We used several types of multivariate analyses to distinguish groups of phorids by phytogeographical regions, hosts and climate, to find gradients of climate throughout the studied area, to define phorid communities in terms of their relationships with gradients of climate, and to test a mechanism for Rapoport's rule. Results  Richness estimations using ICE and Mmean estimators were similar or higher than the observed values depending on the phytogeographical region. Cluster multivariate analyses based on climatic, phytogeographic and host data revealed distinct groupings of Pseudacton. The ‘cerrado’ group was confined to tropical savanna areas. A more ‘widespread’ group included ‘Chaco’ and ‘Maritime’ subgroups defined by their respective association with extreme temperatures or precipitation. Ordination multivariate analyses showed (1) two climatic gradients throughout the study area: one of temperature and the other of precipitation, and (2) that climatic variables significantly explained the observed assemblages of phorids. Positive and negative signs of the eigenvalues from the main axes of a canonical correspondence analysis allowed us to define eight communities whose geographical distribution resembled that of phytogeographical regions. We found a significant and positive correlation between geographical areas and mid latitudinal points, and furthermore, the Mantel test based on climatic variables suggested a mechanism for Rapoport's rule applying in the case of Pseudacteon. Main conclusions Pseudacteon species with greater mid-latitudinal points occupy broader geographical areas and confront more stressful environmental conditions. Because the composition of Pseudacteon communities is largely determined by climatic variables, the correspondence between climates at sites of origin vs. sites of release should be an important consideration in choosing specific phorids for biocontrol efforts. Resumen Metas Solenopsis richteri y S. invicta, dos miembros de las hormigas de fuego del grupo Saevissima, se han tornado serias plagas despues de ser introducidas desde Argentina/Brasil a otros continentes. En Sud America, estas especies, asi como otras Solenopsis, se encuentran distribuidas a lo largo de una gran variedad de habitats y zonas climaticas. En Norte America, S. invicta, que fue introducida sin su fauna parasitoide, ahora se distribuye de costa a costa en el Sur de ese pais. El exito de la introduccion de los foridos Pseudacteon como una estrategia de control biologico ha variado dependiendo de las zonas climaticas. Nuestro objetivo fue juntar toda la informacion sobre los foridos parasitoides de las hormigas de fuego de Argentina y Brasil, para estimar su riqueza y rangos geograficos, para realizar analisis climaticos de sus distribuciones, para definir grupos y comunidades climaticas, y para poner a prueba la regla de Rapoport y un mecanismo que la explique. Ubicacion  Argentina y Brasil (America del Sur). Metodos  Construimos una base de datos de los parasitoides especificos de las hormigas de fuego a lo largo del rango geografico conocido, a partir de datos de colectas de campo, de colecciones de museos, y de registros historicos. Ubicamos en un mapa entre los 10° y 38° LS y entre los 35° y 65° LO, los 123 sitios donde se registraron los parasitoides; en ellos ademas asignamos los valores correspondientes de 15 variables ambientales. Calculamos la riqueza para toda la region asi como para cada provincia fitogeografica, usando curvas de rarefaccion con los estimadores ICE y Mmean. Calculamos los puntos latitudinales medios, los rangos geograficos, y las areas de cada especie. La correlacion entre el punto latitudinal medio y los rangos/areas fue puesta a prueba con la generacion de un modelo nulo producto de la aleatorizacion de las especies. Usamos distintos tipos de analisis multivariados para distinguir grupos de foridos por regiones fitogeograficas, huesped y clima, para encontrar gradientes de clima a lo largo del area estudiada, para definir comunidades de foridos en relacion al clima, y para poner a prueba un mecanismo para la regla de Rapoport. Resultados  Las estimaciones de riqueza, usando ambos estimadores, fue similar o mas alta a la observada dependiendo de las provincias fitogeograficas. Los analisis de clasificacion multivariados basados en provincias fitogeograficas, huespedes y clima, revelaron distintos agrupamientos de Pseudacteon. El grupo del ‘Cerrado’ estuvo confinado a ambientes de savanas. El grupo de ‘Amplia Distribucion’ incluyo al sub-grupo del ‘Chaco’ y al ‘Maritimo’ debido a su respectiva asociacion con la temperatura y precipitacion. Los analisis multivariados de ordenamiento mostraron (1) dos gradientes climaticos en el area de estudio, uno de temperatura y otro de precipitacion, (2) que las variables climaticas explicaron significativamente el ensamble de foridos observado. Los signos, positivos y negativos, de los autovalores de los tres ejes principales del analisis de correspondencia canonica nos permitio definir ocho comunidades cuya distribucion geografica se parecia a la de las provincias fitogeograficas. Encontramos una correlacion positiva y significativa entre las areas geograficas y los puntos latitudinales medios, es mas, el Test de Mantel basado en las variables climaticas permitio identificar un mecanismo para este ensamble de Pseudacteon. Conclusiones principales  Las especies de Pseudacteon con puntos latitudinales medios mayores ocupan areas geograficas mas grandes y confrontan condiciones de stress climatico mayores. Dado que la composicion de las comunidades de Pseudacteon esta en su mayor parte determinada por variables climaticas, la correspondencia climatica entre el sitio de origen y el sitio de liberacion de los parasitoides deberia ser una consideracion importante para la seleccion de especies de foridos para el control biologico.

Patricia J. Folgarait - One of the best experts on this subject based on the ideXlab platform.

  • biogeography and macroecology of phorid flies that attack fire ants in south eastern brazil and argentina
    Journal of Biogeography, 2005
    Co-Authors: Patricia J. Folgarait, M A Pesquero, Sanford D. Porter, Octavio A Bruzzone, Lawrence E. Gilbert
    Abstract:

    Aim  Saevissima group fire ants, Solenopsis richteri and S. invicta, have become serious pests when introduced from Argentina and Brazil to other continents. In South America, Solenopsis are distributed across a great variety of habitats and climates. In North America, S. invicta, introduced free of phorids, now ranges from coast to coast in the south. Success in introducing particular Pseudacteon as agents for the biological control of fire ants has varied across climatic zones. We aimed at assembling all the information about fire ant phorids from Argentina and Brazil, to estimate their richness and geographical ranges, to perform a climatic analysis for these distributions, to define groups and climate-based communities, and to test and elucidate Rapoport's biogeographical rule. Location  Argentina and Brazil (South America). Methods  From field and museum collections and historical records, we developed a database of fire ant-specific phorids throughout their known geographical range. A total of 123 sites with values for 15 climatic variables were mapped between 10° and 38° SL and between 35° and 65° C WL for the presence/absence of phorids. We calculated species richness across all sites combined, and for each phytogeographical region, using rarefaction curves, and ICE and Mmean estimators. We calculated mid-latitudinal points, geographical ranges and areas for each species. The correlation between mid-latitudinal point and ranges/areas was tested against a null model generated from the randomization of the raw distributional data. We used several types of multivariate analyses to distinguish groups of phorids by phytogeographical regions, hosts and climate, to find gradients of climate throughout the studied area, to define phorid communities in terms of their relationships with gradients of climate, and to test a mechanism for Rapoport's rule. Results  Richness estimations using ICE and Mmean estimators were similar or higher than the observed values depending on the phytogeographical region. Cluster multivariate analyses based on climatic, phytogeographic and host data revealed distinct groupings of Pseudacton. The ‘cerrado’ group was confined to tropical savanna areas. A more ‘widespread’ group included ‘Chaco’ and ‘Maritime’ subgroups defined by their respective association with extreme temperatures or precipitation. Ordination multivariate analyses showed (1) two climatic gradients throughout the study area: one of temperature and the other of precipitation, and (2) that climatic variables significantly explained the observed assemblages of phorids. Positive and negative signs of the eigenvalues from the main axes of a canonical correspondence analysis allowed us to define eight communities whose geographical distribution resembled that of phytogeographical regions. We found a significant and positive correlation between geographical areas and mid latitudinal points, and furthermore, the Mantel test based on climatic variables suggested a mechanism for Rapoport's rule applying in the case of Pseudacteon. Main conclusions Pseudacteon species with greater mid-latitudinal points occupy broader geographical areas and confront more stressful environmental conditions. Because the composition of Pseudacteon communities is largely determined by climatic variables, the correspondence between climates at sites of origin vs. sites of release should be an important consideration in choosing specific phorids for biocontrol efforts. Resumen Metas Solenopsis richteri y S. invicta, dos miembros de las hormigas de fuego del grupo Saevissima, se han tornado serias plagas despues de ser introducidas desde Argentina/Brasil a otros continentes. En Sud America, estas especies, asi como otras Solenopsis, se encuentran distribuidas a lo largo de una gran variedad de habitats y zonas climaticas. En Norte America, S. invicta, que fue introducida sin su fauna parasitoide, ahora se distribuye de costa a costa en el Sur de ese pais. El exito de la introduccion de los foridos Pseudacteon como una estrategia de control biologico ha variado dependiendo de las zonas climaticas. Nuestro objetivo fue juntar toda la informacion sobre los foridos parasitoides de las hormigas de fuego de Argentina y Brasil, para estimar su riqueza y rangos geograficos, para realizar analisis climaticos de sus distribuciones, para definir grupos y comunidades climaticas, y para poner a prueba la regla de Rapoport y un mecanismo que la explique. Ubicacion  Argentina y Brasil (America del Sur). Metodos  Construimos una base de datos de los parasitoides especificos de las hormigas de fuego a lo largo del rango geografico conocido, a partir de datos de colectas de campo, de colecciones de museos, y de registros historicos. Ubicamos en un mapa entre los 10° y 38° LS y entre los 35° y 65° LO, los 123 sitios donde se registraron los parasitoides; en ellos ademas asignamos los valores correspondientes de 15 variables ambientales. Calculamos la riqueza para toda la region asi como para cada provincia fitogeografica, usando curvas de rarefaccion con los estimadores ICE y Mmean. Calculamos los puntos latitudinales medios, los rangos geograficos, y las areas de cada especie. La correlacion entre el punto latitudinal medio y los rangos/areas fue puesta a prueba con la generacion de un modelo nulo producto de la aleatorizacion de las especies. Usamos distintos tipos de analisis multivariados para distinguir grupos de foridos por regiones fitogeograficas, huesped y clima, para encontrar gradientes de clima a lo largo del area estudiada, para definir comunidades de foridos en relacion al clima, y para poner a prueba un mecanismo para la regla de Rapoport. Resultados  Las estimaciones de riqueza, usando ambos estimadores, fue similar o mas alta a la observada dependiendo de las provincias fitogeograficas. Los analisis de clasificacion multivariados basados en provincias fitogeograficas, huespedes y clima, revelaron distintos agrupamientos de Pseudacteon. El grupo del ‘Cerrado’ estuvo confinado a ambientes de savanas. El grupo de ‘Amplia Distribucion’ incluyo al sub-grupo del ‘Chaco’ y al ‘Maritimo’ debido a su respectiva asociacion con la temperatura y precipitacion. Los analisis multivariados de ordenamiento mostraron (1) dos gradientes climaticos en el area de estudio, uno de temperatura y otro de precipitacion, (2) que las variables climaticas explicaron significativamente el ensamble de foridos observado. Los signos, positivos y negativos, de los autovalores de los tres ejes principales del analisis de correspondencia canonica nos permitio definir ocho comunidades cuya distribucion geografica se parecia a la de las provincias fitogeograficas. Encontramos una correlacion positiva y significativa entre las areas geograficas y los puntos latitudinales medios, es mas, el Test de Mantel basado en las variables climaticas permitio identificar un mecanismo para este ensamble de Pseudacteon. Conclusiones principales  Las especies de Pseudacteon con puntos latitudinales medios mayores ocupan areas geograficas mas grandes y confrontan condiciones de stress climatico mayores. Dado que la composicion de las comunidades de Pseudacteon esta en su mayor parte determinada por variables climaticas, la correspondencia climatica entre el sitio de origen y el sitio de liberacion de los parasitoides deberia ser una consideracion importante para la seleccion de especies de foridos para el control biologico.

  • Rasgos morfológicos asociados a la viabilidad de pupas en parasitoides del género Pseudacteon (Diptera: Phoridae) Morphological traits associated with pupae viability in Pseudacteon (Diptera: Phoridae) parasitoids
    Sociedad Entomológica Argentina, 2005
    Co-Authors: Patricia J. Folgarait, Monica G Chirino, Lawrence E. Gilbert
    Abstract:

    RESUMEN. Fóridos del género Pseudacteon Coquillett oviponen en forrajeras del género Solenopsis Westwood y empupan en sus cabezas. Se evaluó la relación entre la viabilidad de los parasitoides, la presencia de cuernos respiratorios y el color en los opérculos de los puparios de cuatro especies de Pseudacteon criados sobre Solenopsis invicta Buren y Solenopsis richteri Forel. La presencia de cuernos respiratorios estuvo asociada a la viabilidad de las pupas para las especies consideradas (p < 0,01), pero no el color de los opérculos (p > 0,09); excepto cuando Pseudacteon cultellatus Borgmeier se desarrolló sobre hormigas de la reserva y niñeras de S. invicta (p < 0,01). Los opérculos claros predominaron en P. cultellatus; mientras que en las demás especies, que atacan a hormigas más grandes, predominaron los opérculos castaños. Debido a que los opérculos presentaron un color similar al de la hormiga parasitada, esto representaría un mimetismo por parte del parasitoide para evitar ser detectado por el huésped. Dado que los cuernos respiratorios son necesarios para la supervivencia de la mayoría de las pupas, sugerimos que sean usados como indicadores de eficiencia en los protocolos de cría. Recomendamos usar solo forrajeras dado que las otras castas no parecen ser huéspedes apropiados.ABSTRACT. Pseudacteon Coquillett phorid flies oviposit on Solenopsis Westwood ants and pupate within the ant's head. We have evaluated the relationship between pupae's viability, presence of respiratory horns and the operculum color in four species of Pseudacteon reared on Solenopsis invicta Buren and Solenopsis richteri Forel ants. The presence of respiratory horns was significantly associated with pupae's viability for all species considered (p < 0,001) but operculum color was not (p > 0,09), except (p < 0,01) when Pseudacteon cultellatus Borgmeier had developed on S. invicta nanitic and reserve workers. Pupae with light-colored opercula were more frequent in P. cultellatus, whereas brown opercula were more frequent for the other species that attack bigger ants. Mimetism can be invoked to explain the similarity in opercula color with that of the head of the parasitized ant as a way to avoid recognition by members of the colony. We conclude that the presence of respiratory horns is necessary for pupae survival of most of the pupae and we suggest to use the presence of respiratory horns as an indicator of the efficiency of rearing protocols for this group of parasitoids. We also recommend using forager ants because other casts do not seem to be appropriate hosts

  • Rasgos morfológicos asociados a la viabilidad de pupas en parasitoides del género Pseudacteon (Diptera: Phoridae)
    Sociedad Entomológica Argentina, 2005
    Co-Authors: Patricia J. Folgarait, Monica G Chirino, Lawrence E. Gilbert
    Abstract:

    Fóridos del género Pseudacteon Coquillett oviponen en forrajeras del género Solenopsis Westwood y empupan en sus cabezas. Se evaluó la rela- ción entre la viabilidad de los parasitoides, la presencia de cuernos respiratorios y el color en los opérculos de los puparios de cuatro especies de Pseudacteon criados sobre Solenopsis invicta Buren y Solenopsis richteri Forel. La presencia de cuernos respiratorios estuvo asociada a la viabilidad de las pupas para las especies consideradas (p < 0,01), pero no el color de los opérculos (p > 0,09); excepto cuando Pseudacteon cultellatus Borgmeier se desarrolló sobre hormi- gas de la reserva y niñeras de S. invicta (p < 0,01). Los opérculos claros predomi- naron en P. cultellatus; mientras que en las demás especies, que atacan a hormi- gas más grandes, predominaron los opérculos castaños. Debido a que los opérculos presentaron un color similar al de la hormiga parasitada, esto repre- sentaría un mimetismo por parte del parasitoide para evitar ser detectado por el huésped. Dado que los cuernos respiratorios son necesarios para la superviven- cia de la mayoría de las pupas, sugerimos que sean usados como indicadores de eficiencia en los protocolos de cría. Recomendamos usar solo forrajeras dado que las otras castas no parecen ser huéspedes apropiados

  • seasonal patterns of activity among species of black fire ant parasitoid flies pseudacteon phoridae in argentina explained by analysis of climatic variables
    Biological Control, 2003
    Co-Authors: Patricia J. Folgarait, Octavio Augusto Bruzzone, Lawrence E. Gilbert
    Abstract:

    Abstract We monitored weekly relative abundances of adult female Pseudacteon (Diptera: Phoridae) species between February 1998 and May 2000 in Argentina. Fire ant-phorids were active around mounds of Solenopsis richteri Forel throughout the year. Phorid species richness ranged from six species during the summer-fall, to a single, large species during the winter. Species were classified as winter, summer, or fall-spring species, depending on times of peak mean abundance. We used descriptive multivariate techniques to analyze phorid phenological data (correspondence analysis), climatic data (principal component analysis), and their relationships (canonical correspondence analysis=CCA) at three temporal scales. The long-term mean temperatures, the mean and minimum sampling-time temperature, and the cumulative number of days without rain from the two months preceding each sampling day explained >90% of the variance when the data for sampling dates were averaged across the same months over the two years. Pseudacteon borgmeieri Schmitz, the winter dominant, was associated with lower temperatures and rainfall, whereas Pseudacteon curvatus Borgmeier, the summer dominant, showed the opposite pattern. Among the fall-spring species, Pseudacteon comatus Borgmeier was associated with months of higher maximum temperatures, longer photoperiods, and lower relative humidity. Pseudacteon nudicornis Borgmeier, in contrast, showed the opposite pattern. Pseudacteon tricuspis Borgmeier, was associated with months, typically in fall, having greater rainfall and fewer days with frosts. Implications of these patterns for the process of selecting particular species of S. richteri-attacking Pseudacteon for use in biological control introductions against imported fire ants are discussed in relation to climates of source and release areas.

Dewayne Shoemaker - One of the best experts on this subject based on the ideXlab platform.

  • Disruption of gene expression in hybrids of the fire ants Solenopsis invicta and Solenopsis richteri
    Molecular ecology, 2012
    Co-Authors: Lino Ometto, Dewayne Shoemaker, Kenneth G. Ross, Laurent Keller
    Abstract:

    Transcriptome analysis is a powerful tool for unveiling the distribution and magnitude of genetic incompatibilities between hybridizing taxa. The nature of such incompatibilities is closely associated with the evolutionary histories of the parental species and may differ across tissues and between the sexes. In eusocial insects, the presence of castes that experience divergent selection regimes may result in additional distinct patterns of castespecific hybrid incompatibilities. We analysed levels of expression of >14 000 genes in two life stages of each caste in the fire ants Solenopsis invicta and Solenopsis richteri and in their hybrids. We found strong contributions of both developmental stage and caste to gene expression patterns. In contrast, variability in expression was only weakly associated with taxonomic identity, with hybrid scores falling between those of the two parental species. Hybrid incompatibilities were surprisingly modest, with only 32 genes being mis-expressed, indicating low levels of disruption in gene regulation in hybrids; males and workers each mis-expressed at least seven times as many genes as queens. Interestingly, homologues of many of the mis-expressed genes have been implicated in behavioural variation in Drosophila melanogaster. General expression profiles of hybrids consistently were more similar to those of S. richteri than S. invicta, presumably because S. richteri trans-regulatory elements tend to be dominant and ⁄or because there is an overall bias in the genetic composition of the hybrids towards S. richteri. Altogether, our results suggest that selection acting on each caste may contribute differently to interspecific divergence and speciation in this group of ants.

  • species delimitation in native south american fire ants
    Molecular Ecology, 2005
    Co-Authors: Kenneth G. Ross, Dewayne Shoemaker
    Abstract:

    The taxonomy of fire ants has been plagued by difficulties in recognizing species on the basis of morphological characters. We surveyed allozyme markers and sequences of the mtDNA COI gene in several closely related nominal species from two areas of sympatry in the native ranges to learn whether the morphology-based delimitation of these species is supported by genetic data. We found that Solenopsis invicta and Solenopsis richteri , pest species whose distinctiveness has been debated, appear to be fully reproductively isolated at both study sites. This isolation contrasts with the extensive hybridization occurring between them in the USA, where both have been introduced. We also found strong genetic differentiation consistent with barriers to gene flow between Solenopsis quinquecuspis and the other two species. However, several lines of evidence suggest that nuclear and mitochondrial genes of S. invicta and S. richteri are introgressing into S. quinquecuspis . The latter apparently is a recently derived member of the clade that includes all three species, suggesting that there has been insufficient time for its full development of intrinsic isolating mechanisms. Finally, our discovery of genetically distinct populations within both S. invicta and S. richteri suggests the presence of previously unrecognized (cryptic) species. Their existence, together with the difficulties in developing diagnostic morphological characters for described species, imply that the group is actively radiating species and that morphological divergence generally does not keep pace with the development of reproductive isolation and neutral genetic divergence in this process.

  • social parasitism in fire ants Solenopsis spp a potential mechanism for interspecies transfer of wolbachia
    Molecular Ecology, 2005
    Co-Authors: Franck Dedeine, Michael E Ahrens, Luis A Calcaterra, Dewayne Shoemaker
    Abstract:

    One possible mechanism for interspecific transfer of Wolbachia is through the intimate contact between parasites and their hosts. We surveyed 10 species of fly parasitoids ( Pseudacteon spp.) and one inquiline social parasite, Solenopsis daguerrei , for the presence and sequence identity ( wsp gene) of Wolbachia . Two Wolbachia variants infecting S. daguerrei were identical to known variants infecting the two common ant host species, Solenopsis invicta and Solenopsis richteri , suggesting possible transfers of Wolbachia between this parasite and their hosts have occurred. Our data also revealed an unexpectedly high diversity of Wolbachia variants within S. daguerrei : up to eight variants were found within each individual, which, to our knowledge, is the highest reported number of Wolbachia variants infecting a single individual of any host species.

  • Alternative genetic foundations for a key social polymorphism in fire ants.
    Genetics, 2003
    Co-Authors: Kenneth G. Ross, Michael J. B. Krieger, Dewayne Shoemaker
    Abstract:

    Little is known about the genetic foundations of colony social organization. One rare example in which a single major gene is implicated in the expression of alternative social organizations involves the presumed odorant-binding protein gene Gp-9 in fire ants. Specific amino acid substitutions in this gene invariably are associated with the expression of monogyny (single queen per colony) or polygyny (multiple queens per colony) in fire ant species of the Solenopsis richteri clade. These substitutions are hypothesized to alter the abilities of workers to recognize queens and thereby regulate their numbers in a colony. We examined whether these same substitutions underlie the monogyny/polygyny social polymorphism in the distantly related fire ant S. geminata. We found that Gp-9 coding region sequences are identical in the polygyne and monogyne forms of this species, disproving our hypothesis that one or a few specific amino acid replacements in the protein are necessary to induce transitions in social organization in fire ants. On the other hand, polygyne S. geminata differs genetically from the monogyne form in ways not mirrored in the two forms of S. invicta, a well-studied member of the S. richteri clade, supporting the conclusion that polygyny did not evolve via analogous routes in the two lineages. Specifically, polygyne S. geminata has lower genetic diversity and different gene frequencies than the monogyne form, suggesting that the polygyne form originated via a founder event from a local monogyne population. These comparative data suggest an alternative route to polygyny in S. geminata in which loss of allelic variation at genes encoding recognition cues has led to a breakdown in discrimination abilities and the consequent acceptance of multiple queens in colonies.