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Stefano Colazza - One of the best experts on this subject based on the ideXlab platform.
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Intraguild Interactions between Two Egg Parasitoids of a True Bug in Semi-Field and Field Conditions
2016Co-Authors: Ezio Peri, Antonino Cusumano, Valentina Amodeo, Eric Wajnberg, Stefano ColazzaAbstract:Research on interspecific competitive interactions among insect parasitoids has often been characterized by laboratory studies in which host insects are exposed to female parasitoids of different species in various sequences and combinations. In the last years, an increasing number of studies have investigated interspecific interactions under field and semi-field conditions although just a few number of works focused on egg parasitoids. In this work, we undertook a two-year study to investigate interspecific interactions between Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), two egg parasitoids of the pest Nezara viridula (L.) (Heteroptera: Pentatomidae) that co-occur in cultivated crops. Under semi-field (in out-door mesh cages) and field conditions, we investigated: 1) the seasonal occurrence of competing parasitoid species on sentinel egg masses; 2) the impact achieved by competing species on the shared host on naturally laid egg masses; 3) the outcome of intraguild interactions under controlled conditions. Results from sentinel egg masses showed that T. basalis occurs in May and successfully parasitizes hosts until the end of September/beginning of October, whereas O. telenomicida is mainly occurring in July-August. In both years, it was found that T. basalis is predominant. From naturally laid egg masses, results indicated that T. basalis achieves higher impact on the hosts, even in those egg masses which are parasitized by more than one female of different species ( = multiparasitism). Results from manipulating intraguild interactions showed that T. basalis achieves higher impact on N
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Intraguild interactions between two egg parasitoids of a true bug in semi-field and field conditions
PLoS ONE, 2014Co-Authors: Ezio Peri, Antonino Cusumano, Valentina Amodeo, Eric Wajnberg, Stefano ColazzaAbstract:Research on interspecific competitive interactions among insect parasitoids has often been characterized by laboratory studies in which host insects are exposed to female parasitoids of different species in various sequences and combinations. In the last years, an increasing number of studies have investigated interspecific interactions under field and semi-field conditions although just a few number of works focused on egg parasitoids. In this work, we undertook a two-year study to investigate interspecific interactions between Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), two egg parasitoids of the pest Nezara viridula (L.) (Heteroptera: Pentatomidae) that co-occur in cultivated crops. Under semi-field (in out-door mesh cages) and field conditions, we investigated: 1) the seasonal occurrence of competing parasitoid species on sentinel egg masses; 2) the impact achieved by competing species on the shared host on naturally laid egg masses; 3) the outcome of intraguild interactions under controlled conditions. Results from sentinel egg masses showed that T. basalis occurs in May and successfully parasitizes hosts until the end of September/beginning of October, whereas O. telenomicida is mainly occurring in July-August. In both years, it was found that T. basalis is predominant. From naturally laid egg masses, results indicated that T. basalis achieves higher impact on the hosts, even in those egg masses which are parasitized by more than one female of different species (= multiparasitism). Results from manipulating intraguild interactions showed that T. basalis achieves higher impact on N. viridula when released alone, but it suffers from competition with O. telenomicida. The ecological factors that play a role in intraguild interactions in the context of biological control perspective are discussed.
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The Egg Parasitoid Trissolcus basalis uses n-nonadecane, a Cuticular Hydrocarbon from its Stink Bug Host Nezara viridula, to Discriminate Between Female and Male Hosts
Journal of Chemical Ecology, 2007Co-Authors: Stefano Colazza, Ezio Peri, Gloria Aquila, Claudio Pasquale, Jocelyn G. MillarAbstract:Contact kairomones from adult southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae) that elicit foraging behavior of the egg parasitoid Trissolcus basalis (Wollaston) were investigated in laboratory experiments. Chemical residues from tarsi and scutella of N. viridula induced foraging by gravid female T. basalis . Residues from body parts of female N. viridula elicited stronger responses than those from the corresponding body parts of males. Deproteinized tarsi still elicited searching responses from wasps, indicating that the kairomone was not proteinaceous. Hexane extracts of host cuticular lipids induced searching responses from T. basalis , with a strong preference for extracts from female hosts. Extracts consisted primarily of linear alkanes from n C_19 to n C_34, with quantitative and qualitative differences between the sexes. Extracts of female N. viridula contained more n C_23, n C_24, and n C_25 than the corresponding extracts from males, whereas n C_19 was detected only in extracts from males. Direct-contact solid phase microextraction (DC-SPME) of N. viridula cuticle and of residues left by adult bugs walking on a glass plate confirmed gender-specific differences in n C_19. Trissolcus basalis females responded weakly to a reconstructed blend of the straight-chain hydrocarbons, suggesting that minor components other than linear alkanes must be part of the kairomone. Addition of n C_19 to hexane extracts of female N. viridula significantly reduced the wasps’ arrestment responses, similar to wasps’ responses to hexane extracts of male hosts. Overall, our results suggest that a contact kairomone that elicits foraging by T. basalis females is present in the cuticular lipids of N. viridula , and that the presence or absence of n C_19 allows T. basalis females to distinguish between residues left by male or female hosts. The ecological significance of these results in the host location behavior of scelionid egg parasitoids is discussed.
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kairomone involvement in the host specificity of the egg parasitoid trissolcus basalis hymenoptera scelionidae
European Journal of Endocrinology, 2006Co-Authors: Gianandrea Salerno, Ezio Peri, Stefano Colazza, Ferdinando BinAbstract:This paper reports the results of a comparative laboratory analysis of the behavioural responses of the egg parasitoid Tris- solcus basalis (Wollaston) (Hymenoptera: Scelionidae) to semiochemical cues from four species of pentatomid bugs, Nezara viridula (L.), Eurydema ventrale Klt., Murgantia histrionica Hahn. and Graphosoma semipunctatum F. (Heteroptera: Pentatomidae). In a Y-tube olfactometer, T. basalis was attracted by volatile chemicals from N. viridula, but not from other pentatomid species. In an open arena, the parasitoid reacted to chemical trails left on filter paper by all the species but most intensely to those left by N. viridula. However, upon encountering pentatomid eggs, T. basalis examined more intensely and probed more frequently the eggs of G. semipunctatum than those of the other species. The parasitoid only parasitized and emerged from eggs of G. semipunctatum and N. viridula; those of the other species were unsuitable. Therefore N. viridula is semiochemically confirmed to be a coevolved host (old association) of T. basalis, whereas G. semipunctatum may be a potential non-coevolved host (new association). The utility of these tests for defining a parasitoids' host specificity and in assessing the risk of non-target effects in biological control is discussed.
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source of an egg kairomone for trissolcus basalis a parasitoid of nezara viridula
Physiological Entomology, 1993Co-Authors: Ferdinando Bin, Stefano Colazza, S B Vinson, Michael R Strand, Walker A JonesAbstract:Abstract. The eggs of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), are successfully attacked by Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae) and are recognized as hosts by a secretion applied to the egg chorion. This secretion is produced by the follicular cells in the proximal region of the ovariole of the female pentatomid and functions as an adhesive for attaching the eggs to the oviposition substrate. The adhesive and kairomone activity could be partially removed with water. This water extract elicited host recognition behaviour in T. basalis when applied to glass beads which stuck together as the extract dried. The adhesive and kairomonal activity was removed completely with acetone since acetone-washed host eggs were not recognized by T. basalis. Application of the acetone extract to glass beads stimulated ovipositional probes by T. basalis. The adhesive appeared to be composed of a mucopolysaccharide–protein complex.
Douglas D. Colwell - One of the best experts on this subject based on the ideXlab platform.
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species composition of gasterophilus spp diptera oestridae causing equine gastric myiasis in southern italy parasite biodiversity and risks for extinction
Veterinary Parasitology, 2005Co-Authors: Domenico Otranto, Piermarino Milillo, Gioia Capelli, Douglas D. ColwellAbstract:Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus Nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on the seasonal variation of the infection pattern in southern Italy, 152 native horses were necropsied from January to December 2003 and Gasterophilus larvae were collected from the stomach, the small intestine and the rectum of each of them. On the whole, 125 (82.2%) horses were infected by larvae of Gasterophilus spp. and 214 second stage larvae (L2) and 13,342 third stage larvae (L3) collected. Five species of Gasterophilus were identified with the following prevalence: G. intestinalis=95.2%, G. Nasalis=44.8%, G. inermis=15.2%, G. pecorum=2.6% and G. haemorrhoidalis=0.8%. L3 were retrieved throughout the observation period with the highest mean burdens from January to August 2003 while the lowest mean was registered from September to November 2003. L2 were collected in February-March 2003 and from September to December 2003. The majority of the animals (n=66, 43.4%) were infected with a single Gasterophilus species, however, 45 animals (29.6%) harboured 2 species, 12 animals (7.9%) 3 species and 2 animals (1.3%) 4 species. The trend of abundance in the L3 of G. intestinalis and G. Nasalis, the most represented species, was highly concordant (r=0.5, p<0.001). A retrospective comparison of our results and of other data from four seasons of observation (1983-1986) in central Italy showed that the number of G. inermis, G. pecorum and G. haemorrhoidalis have been decreasing relative to G. intestinalis and G. Nasalis which may suggest tendency toward the extinction of the three former species of Gasterophilus.
Domenico Otranto - One of the best experts on this subject based on the ideXlab platform.
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molecular comparison of gasterophilus intestinalis and gasterophilus Nasalis from two distinct areas of poland and italy based on cox1 sequence analysis
Veterinary Parasitology, 2010Co-Authors: Monika Pawlasopiela, łukasz Wojciech, Z Soltysiak, Domenico Otranto, Maciej UgorskiAbstract:In this study, Gasterophilus intestinalis and Gasterophilus Nasalis collected from horses in northeastern Poland and southern Italy were genetically compared. The cox1 sequences of the Polish and Italian G. Nasalis larvae revealed a higher degree of geographic genetic diversity, with an intra-specific variation rate of 1.27%, than the G. Nasalis specimens collected in Poland (intra-specific variation rate: 0.49%) and those collected in Italy (intra-specific variation rate: 0.58%). However, the level of genetic homology of the Polish and Italian G. intestinalis specimens (intra-specific variation rate: 1.27%) was similar to that of the G. intestinalis larvae collected in northeastern Poland (intra-specific variation rate: 0.94%) and those collected in southern Italy (intra-specific variation rate: 1.16%). Analysis of the restriction enzyme sites in the coxI gene of G. Nasalis and G. intestinalis showed that the nucleotide polymorphism (NP) at position 1050 of this gene determines cleavage by MnlI only in G. Nasalis, making it possible to differentiate the two species using PCR-RFLP. Interestingly, comparison of the nucleotide sequences of the PCR-amplified coxI gene fragments from the Italian specimens of G. Nasalis with other analyzed cox1 genes revealed an additional NP at position 1236 of cox1 gene, recognized by MnlI. The present study shows that G. Nasalis specimens from different geographical areas display a level of genetic diversity which can influence PCR-RFLP analysis.
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species composition of gasterophilus spp diptera oestridae causing equine gastric myiasis in southern italy parasite biodiversity and risks for extinction
Veterinary Parasitology, 2005Co-Authors: Domenico Otranto, Piermarino Milillo, Gioia Capelli, Douglas D. ColwellAbstract:Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus Nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on the seasonal variation of the infection pattern in southern Italy, 152 native horses were necropsied from January to December 2003 and Gasterophilus larvae were collected from the stomach, the small intestine and the rectum of each of them. On the whole, 125 (82.2%) horses were infected by larvae of Gasterophilus spp. and 214 second stage larvae (L2) and 13,342 third stage larvae (L3) collected. Five species of Gasterophilus were identified with the following prevalence: G. intestinalis=95.2%, G. Nasalis=44.8%, G. inermis=15.2%, G. pecorum=2.6% and G. haemorrhoidalis=0.8%. L3 were retrieved throughout the observation period with the highest mean burdens from January to August 2003 while the lowest mean was registered from September to November 2003. L2 were collected in February-March 2003 and from September to December 2003. The majority of the animals (n=66, 43.4%) were infected with a single Gasterophilus species, however, 45 animals (29.6%) harboured 2 species, 12 animals (7.9%) 3 species and 2 animals (1.3%) 4 species. The trend of abundance in the L3 of G. intestinalis and G. Nasalis, the most represented species, was highly concordant (r=0.5, p<0.001). A retrospective comparison of our results and of other data from four seasons of observation (1983-1986) in central Italy showed that the number of G. inermis, G. pecorum and G. haemorrhoidalis have been decreasing relative to G. intestinalis and G. Nasalis which may suggest tendency toward the extinction of the three former species of Gasterophilus.
J. Huignard - One of the best experts on this subject based on the ideXlab platform.
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Interspecific Relationships Between the Solitary Ectoparasitoid, Eupelmus vuilleti (Crw.) (Eupelmidae), and Its Sympatric Species, Dinarmus basalis (Rond.) (Pteromalidae), in the Presence of Their Host, Callosobruchus maculatus Pic (Coleoptera Bruchi
Journal of Insect Behavior, 2004Co-Authors: B. Jaloux, J. Huignard, A. Sanon, J. P. MongeAbstract:The eupelmid Eupelmus vuilleti CRW. and the pteromalid Dinarmus basalis Rond. are sympatric in West Africa. The reproduction of E. vuilleti and D. basalis females was analyzed in 10, 20, and 40 host patches when present alone or together. In 10- and 20-hosts patches, the presence of E. vuilleti affected the reproduction and offspring survival chances of D. basalis. In 40-hosts patch, only the offspring survival of D. basalis was affected by the presence of E. vuilleti. In contrast, the presence of D. basalis did not influence the reproduction of E. vuilleti and the survival chances of its offspring at all host densities tested. Multiparasitism did not occur at random. In a choice test, E. vuilleti showed a preference for hosts previously parasitized by D. basalis on healthy hosts. This attraction is mediated by chemical markers deposited by D. basalis females on the surface of the seed. At high host density, the likelihood of encountering a seed containing a host previously parasitized by D. basalis was lower for E. vuilleti, affecting moderately D. basalis reproductive success.
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analysis of the insecticidal activity of methylisothiocyanate on callosobruchus maculatus f coleoptera bruchidae and its parasitoid dinarmus basalis rondani hymenoptera pteromalidae
Journal of Stored Products Research, 2002Co-Authors: A. Sanon, M Garba, Jacques Auger, J. HuignardAbstract:Abstract The bruchid Callosobruchus maculatus causes major losses during the storage of the seeds of Vigna unguiculata in West Africa. An endemic parasitoid, the pteromalid Dinarmus basalis is present in the stores and can reduce the increase in bruchid populations. African farmers often place in the stores the leaves of a shrub, Boscia senegalensis Lam.(Capparaceae), which release methylisothiocyanate (MITC). This compound is toxic to adult bruchids and could reduce seed losses but its influence on the bruchid natural enemy D. basalis was hitherto unknown. The susceptibility of C. maculatus and D. basalis to MITC was assessed under laboratory conditions. The susceptibility of adults of both species towards MITC were similar. After a 24 h exposure, the LC 50 was respectively 0.48 and 0.54 mg/l for C. maculatus and D. basalis . The ovicidal activity of this compound was high; the LC 50 of C. maculatus eggs was 0.04 mg/l after a 24 h exposure to MITC. High MITC concentrations only slightly affected the survival of C. maculatus during its post-embryonic development in the seeds of V. unguiculata . Gas chromatographic analysis demonstrated that 25–35% of the MITC present in the atmosphere of the experimental jars was absorbed by the seeds but concentrations inside the cotyledons were too low to influence the survival of the C. maculatus larvae. The D. basalis larvae developing at the expense of their host inside the larval galleries, were more affected by the treatment. The introduction of B. senegalensis releasing MITC in the storage systems could reduce the density of the parasitoid population and so increase the seed losses by permitting the development of the bruchid population.
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the consequences of interspecific competition between dinarmus basalis rond hymenoptera pteromalidae and eupelmus vuilleti crw hymenoptera eupelmidae on the development of their host populations
Acta Oecologica-international Journal of Ecology, 1995Co-Authors: J. P. Monge, P Dupont, A Idi, J. HuignardAbstract:En region tropicale seche au Niger deux especes de coleopteres, Bruchidius atrolineatus (Pic) et Callosobruchus maculatus (F) sont sympatriques et se developpent aux depens du niebe Vigna unguiculata (Walp). Deux especes d'ectoparasitoides Eupelmus vuilleti (CRW) et Dinarmus basalis (Rond) sont presents dans les champs puis dans les stocks apres la recolte. Quand les deux especes de bruches sont presentes, la densite de B. atrolineatus est elevee au debut du stockage puis decroit; celle de C. maculatus devient progressivement la plus importante; ce qui explique sa dominance. A partir de fevrier, la densite de la population d'E. vuilleti augmente alors que celle de D. basalis reste basse. La competition interspecifique entre les deux parasitoides explique cette difference. Les etudes experimentales dans les petites structures de stockage montrent que les parasitoides percoivent la presence des hotes deja parasites, mais leurs comportements sont differents. E. vuilleti multiparasite les hotes portant les oeufs ou les larves de D. basalis alors que D. basalis evite les hotes parasites par E. vuilleti. En conditions naturelles, dans les systemes de stockage et en l'absence de competition interspecifique, D. basalis a d'importantes capacites parasitaires. C'est l'espece qui limite le mieux la croissance de la population de C. maculatus. Par contre, lorsque les deux especes de parasitoides sont introduites, la densite de D. basalis est faible et varie peu tandis que celle d'E. vuilleti augmente progressivement. En presence des deux parasitoides, le taux d'accroissement de la population de C. maculatus reste eleve.
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Analysis of multiparasitism by Eupelmus vuilleti (Craw) (Eupelmidae) and Dinarmus basalis (Rond) (Pteromalidae) in the presence of one of their common hosts, Bruchidius atrolineatus (Pic) (Coleoptera Bruchidae).
Oecologia, 1993Co-Authors: Laurent Lévêque, J. P. Monge, Danielle Rojas-rousse, Franz Van Alebeek, J. HuignardAbstract:Bruchidius atrolineatus (Pic) is a tropical beetle (Coleoptera Bruchidae) that develops during the larval and pupal stages in the seeds of a legume Vigna unguiculata (Walp). Two species of Hymenoptera, Dinarmus basalis (Rond) and Eupelmus vuilleti (Craw), solitary ectoparasitoids of the larvae and pupae of B. atrolineatus, were introduced successively in the presence of their hosts, varying the interval between the two introductions. When D. basalis females were introduced 24 h, 3 days or 7 days after E. vuilleti, multiparasitism was low. The females had low fecundity, and their eggs were not distributed randomly over the different available hosts. When E. vuilleti females were introduced second, they oviposited on the different hosts availabe and did not avoid multiparasitism. The presence of hosts already parasitised by D. basalis increased the reproduction of E. vuilleti, and the fecundity of the females was higher than in control batches with E. vuilleti alone. E. vuilleti seems capable of detecting the ovipositor shafts drilled by the D. basalis females, and by introducing its own ovipositors killing the D. basalis eggs or larvae. When interspecific competition was occurring the number of E. vuilleti adults emerging from the seeds was no different from that observed in control batches with E. vuilleti alone, and there were always fewer D. basalis adults than in control batches (D. basalis alone). This interspecific competition reduces the influence of the two parasitoids in the biological control of bruchid populations.
Ezio Peri - One of the best experts on this subject based on the ideXlab platform.
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Intraguild Interactions between Two Egg Parasitoids of a True Bug in Semi-Field and Field Conditions
2016Co-Authors: Ezio Peri, Antonino Cusumano, Valentina Amodeo, Eric Wajnberg, Stefano ColazzaAbstract:Research on interspecific competitive interactions among insect parasitoids has often been characterized by laboratory studies in which host insects are exposed to female parasitoids of different species in various sequences and combinations. In the last years, an increasing number of studies have investigated interspecific interactions under field and semi-field conditions although just a few number of works focused on egg parasitoids. In this work, we undertook a two-year study to investigate interspecific interactions between Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), two egg parasitoids of the pest Nezara viridula (L.) (Heteroptera: Pentatomidae) that co-occur in cultivated crops. Under semi-field (in out-door mesh cages) and field conditions, we investigated: 1) the seasonal occurrence of competing parasitoid species on sentinel egg masses; 2) the impact achieved by competing species on the shared host on naturally laid egg masses; 3) the outcome of intraguild interactions under controlled conditions. Results from sentinel egg masses showed that T. basalis occurs in May and successfully parasitizes hosts until the end of September/beginning of October, whereas O. telenomicida is mainly occurring in July-August. In both years, it was found that T. basalis is predominant. From naturally laid egg masses, results indicated that T. basalis achieves higher impact on the hosts, even in those egg masses which are parasitized by more than one female of different species ( = multiparasitism). Results from manipulating intraguild interactions showed that T. basalis achieves higher impact on N
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Intraguild interactions between two egg parasitoids of a true bug in semi-field and field conditions
PLoS ONE, 2014Co-Authors: Ezio Peri, Antonino Cusumano, Valentina Amodeo, Eric Wajnberg, Stefano ColazzaAbstract:Research on interspecific competitive interactions among insect parasitoids has often been characterized by laboratory studies in which host insects are exposed to female parasitoids of different species in various sequences and combinations. In the last years, an increasing number of studies have investigated interspecific interactions under field and semi-field conditions although just a few number of works focused on egg parasitoids. In this work, we undertook a two-year study to investigate interspecific interactions between Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), two egg parasitoids of the pest Nezara viridula (L.) (Heteroptera: Pentatomidae) that co-occur in cultivated crops. Under semi-field (in out-door mesh cages) and field conditions, we investigated: 1) the seasonal occurrence of competing parasitoid species on sentinel egg masses; 2) the impact achieved by competing species on the shared host on naturally laid egg masses; 3) the outcome of intraguild interactions under controlled conditions. Results from sentinel egg masses showed that T. basalis occurs in May and successfully parasitizes hosts until the end of September/beginning of October, whereas O. telenomicida is mainly occurring in July-August. In both years, it was found that T. basalis is predominant. From naturally laid egg masses, results indicated that T. basalis achieves higher impact on the hosts, even in those egg masses which are parasitized by more than one female of different species (= multiparasitism). Results from manipulating intraguild interactions showed that T. basalis achieves higher impact on N. viridula when released alone, but it suffers from competition with O. telenomicida. The ecological factors that play a role in intraguild interactions in the context of biological control perspective are discussed.
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The Egg Parasitoid Trissolcus basalis uses n-nonadecane, a Cuticular Hydrocarbon from its Stink Bug Host Nezara viridula, to Discriminate Between Female and Male Hosts
Journal of Chemical Ecology, 2007Co-Authors: Stefano Colazza, Ezio Peri, Gloria Aquila, Claudio Pasquale, Jocelyn G. MillarAbstract:Contact kairomones from adult southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae) that elicit foraging behavior of the egg parasitoid Trissolcus basalis (Wollaston) were investigated in laboratory experiments. Chemical residues from tarsi and scutella of N. viridula induced foraging by gravid female T. basalis . Residues from body parts of female N. viridula elicited stronger responses than those from the corresponding body parts of males. Deproteinized tarsi still elicited searching responses from wasps, indicating that the kairomone was not proteinaceous. Hexane extracts of host cuticular lipids induced searching responses from T. basalis , with a strong preference for extracts from female hosts. Extracts consisted primarily of linear alkanes from n C_19 to n C_34, with quantitative and qualitative differences between the sexes. Extracts of female N. viridula contained more n C_23, n C_24, and n C_25 than the corresponding extracts from males, whereas n C_19 was detected only in extracts from males. Direct-contact solid phase microextraction (DC-SPME) of N. viridula cuticle and of residues left by adult bugs walking on a glass plate confirmed gender-specific differences in n C_19. Trissolcus basalis females responded weakly to a reconstructed blend of the straight-chain hydrocarbons, suggesting that minor components other than linear alkanes must be part of the kairomone. Addition of n C_19 to hexane extracts of female N. viridula significantly reduced the wasps’ arrestment responses, similar to wasps’ responses to hexane extracts of male hosts. Overall, our results suggest that a contact kairomone that elicits foraging by T. basalis females is present in the cuticular lipids of N. viridula , and that the presence or absence of n C_19 allows T. basalis females to distinguish between residues left by male or female hosts. The ecological significance of these results in the host location behavior of scelionid egg parasitoids is discussed.
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kairomone involvement in the host specificity of the egg parasitoid trissolcus basalis hymenoptera scelionidae
European Journal of Endocrinology, 2006Co-Authors: Gianandrea Salerno, Ezio Peri, Stefano Colazza, Ferdinando BinAbstract:This paper reports the results of a comparative laboratory analysis of the behavioural responses of the egg parasitoid Tris- solcus basalis (Wollaston) (Hymenoptera: Scelionidae) to semiochemical cues from four species of pentatomid bugs, Nezara viridula (L.), Eurydema ventrale Klt., Murgantia histrionica Hahn. and Graphosoma semipunctatum F. (Heteroptera: Pentatomidae). In a Y-tube olfactometer, T. basalis was attracted by volatile chemicals from N. viridula, but not from other pentatomid species. In an open arena, the parasitoid reacted to chemical trails left on filter paper by all the species but most intensely to those left by N. viridula. However, upon encountering pentatomid eggs, T. basalis examined more intensely and probed more frequently the eggs of G. semipunctatum than those of the other species. The parasitoid only parasitized and emerged from eggs of G. semipunctatum and N. viridula; those of the other species were unsuitable. Therefore N. viridula is semiochemically confirmed to be a coevolved host (old association) of T. basalis, whereas G. semipunctatum may be a potential non-coevolved host (new association). The utility of these tests for defining a parasitoids' host specificity and in assessing the risk of non-target effects in biological control is discussed.
