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Leslie C. Lewis - One of the best experts on this subject based on the ideXlab platform.
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flight behaviour of european corn borer infected with Nosema pyrausta
Journal of Applied Entomology, 2011Co-Authors: David L Dorhout, Leslie C. Lewis, Thomas W Sappington, Marlin E RiceAbstract:The microsporidian Nosema pyrausta Paillot is a common and widespread pathogen of European corn borer, Ostrinia nubilalis (Hiibner), in North America and Europe. Nosema negatively affects European corn borer longevity and fecundity. In this study, we used flight mills to examine the effects of Nosema infection on flight activity of unmated males and females at 1 and 3 days after pupal eclosion, taking the level of infection, as measured by number of Nosema spores per mg of tissue, into consideration. Nosema infection had a significant negative effect on distance, duration and speed of the longest uninterrupted flight, as well as on total distance and duration of flight of 1-day-old males, but not of 3-day-old males or females of either age. However, when insects with a light infection (<15 spores/mg) were pooled with uninfected moths, significant negative effects of a moderate/heavy infection (≥15 spores/mg) were observed for most flight parameters in 1-day-old, but not 3-day-old, moths of both sexes. The magnitude of reduction was often substantial: e.g., distance and duration were sevenfold, and 3.5-fold less, respectively, in 1-day-old females with a moderate/heavy infection. Flight distance and duration were significantly negatively correlated with level of Nosema infection in 1-day-old, but not 3-day-old, moths of both sexes. The percentage of moths of either sex or age with a moderate/heavy Nosema infection flying given distances was less than that of lightly infected (<15 spores/mg) moths. Among uninfected adults, forewing length was positively correlated with several measures of flight performance in males, but not females. However, some performance measures were correlated with wing length in females when infected with Nosema. Nosema infection was associated with reduced adult weight, but not forewing length, suggesting that negative effects of Nosema infection on flight performance are related to reduced energy reserves rather than smaller body size per se.
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effects of infection with Nosema pyrausta on survival and development of offspring of laboratory selected bt resistant and bt susceptible european corn borers
Journal of Invertebrate Pathology, 2010Co-Authors: Miriam D Lopez, Leslie C. Lewis, Douglas V. SumerfordAbstract:Abstract Infection with Nosema pyrausta Paillot lengthens developmental period of Bt-susceptible Ostrinia nubilalis (Hubner) to a similar extent as feeding on Cry1Ab-incorporated diet in Cry1Ab-resistant O. nubilalis, and these two factors combined lengthen developmental period further than either alone. Resistant O. nubilalis mating with infected susceptible, or infected resistant partners would produce partially- and fully-resistant offspring, respectively, infected with N. pyrausta. To investigate the impacts on the progeny of such matings, test crosses were set up to produce partially- and fully Cry1Ab-resistant O. nubilalis offspring transovarially infected and not infected with N. pyrausta, which were exposed to Cry1Ab toxin at doses of 0, 3, or 30 ng/cm2 for 7 days. Transovarial infection with N. pyrausta significantly decreased 7 day survival of partially and fully-resistant O. nubilalis feeding on 30 ng/cm2 Cry1Ab. In addition, N. pyrausta infection delayed larval development (as measured by weight) of partially- and fully-resistant O. nubilalis feeding on 3 and 30 ng/cm2 Cry1Ab. Impacts of natural enemies on target pests may have the potential to impact evolution of resistance. N pyrausta-infected O. nubilalis are more strongly affected by feeding on Bt, and would be less likely to survive to adulthood to pass on resistance to the next generation. This indigenous microsporidium may work to delay evolution of resistance in O. nubilalis by lowering their ability to survive on Bt.
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Nosema pyrausta and cry1ab incorporated diet led to decreased survival and developmental delays in european corn borer
Entomologia Experimentalis Et Applicata, 2010Co-Authors: Miriam D Lopez, Douglas V. Sumerford, Leslie C. LewisAbstract:The high dose/refixge strategy for delaying evolution of resistance to Bt maize [Zea mays L. (Poaceae) ] relies on random mating between resistant European corn borers, Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae), and susceptible O. nubilalis from the refuge. However, differences in developmental rate caused by feeding on Bt maize, or infection with the microsporidium Nosema pyrausta Paillot (Microsporida: Nosematidae) may result in assortative mating. Developmental delays and mortality caused by infection with N. pyrausta and feeding on Bt maize were quantified alone and in combination in CrylAb-resistant and susceptible O. nubilalis. Feeding on Cry1Ab-incorporated diet significantly increased number of days from hatch to pupation and decreased survival in the resistant population. Infection with N. pyrausta increased mortality and lengthened development in both the resistant and susceptible populations. The combination of CrylAb-incorporated diet and infection with N. pyrausta in resistant O. nubilalis lengthened development and increased mortality to a greater extent than either factor alone. Greater larval delays of resistant O. nubilalis feeding on Bt maize could lead to temporal isolation from adults emerging from refuge maize. The resulting assortative mating would hasten the evolution of resistance. Developmental delays caused by infection with N. pyrausta may increase the likelihood of mating between resistant and infected susceptible adults emerging from refuge maize, producing infected offspring that are also more susceptible to Bt maize.
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Nosema pyrausta its biology history and potential role in a landscape of transgenic insecticidal crops
Biological Control, 2009Co-Authors: Leslie C. Lewis, Denny J Bruck, Jarrad R Prasifka, Earle S RaunAbstract:Nosema pyrausta, an entomopathogenic microsporidium, is an important population regulator of the European corn borer, Ostrinia nubilalis. This manuscript is a review of research on the relationships between N. pyrausta and O. nubilalis. N. pyrausta was described from O. nubilalis in Hungary in 1927 and from O. nubilalis in IA in 1950. It affects the basic biology of O. nubilalis by slowing larval development, reducing percentage pupation, and decreasing adult longevity, oviposition and fecundity. Infections are maintained in a population by vertical and horizontal transmission. Success of vertical transmission depends on intensity of infection. Horizontal transmission is dependent on stage of larval development at time of infection, quantity of inoculum, and host density. Abiotic and biotic factors coupled with N. pyrausta usually have an additive effect in decreasing the fitness of O. nubilalis, i.e., cold temperatures reduce fecundity and increase larval mortality, host plant resistance reduces the number of larvae per plant. Also, microbial and chemical insecticides are more effective in reducing plant feeding if the insect is infected with N. pyrausta. Predators in general feed on N. pyrausta-infected O. nubilalis with no decrease in fitness. Parasitoids do coexist with N. pyrausta, however, parasitoid fecundity is usually reduced when developing in a N. pyrausta-infected host. Previously unreported data are presented on the prevalence of N. pyrausta in O. nubilalis populations from many parts of the US. These data demonstrate that N. pyrausta continues to be present and fluctuate in populations of O. nubilalis as it has since its discovery in the US. Also, the dynamics of its presence remain similar through changes in corn production including crop rotations, reduced tillage and transgenic insect-resistant varieties.
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Dynamics of Nosema pyrausta in natural populations of the European corn borer, Ostrinia nubilalis : A six-year study
Biocontrol, 2006Co-Authors: Leslie C. Lewis, Douglas V. Sumerford, Lori A. Bing, Robert D. GunnarsonAbstract:Nosema pyrausta (Paillot) (Microsporida: Nosematidae) is an obligatory intracellular parasite of the European corn borer, Ostrinia nubilalis (Hubner) (Lepi- doptera: Crambidae). This pathogen is maintained in natural populations of O. nubilalis by both horizontal and vertical transmission. The impact of N. pyrausta on fecundity of adults and survival of larvae has been well documented in laboratory and field research. In an extensive study covering a 6 year period at one site, we described the effect of N. pyrausta within O. nubilalis populations in a continuous corn following corn ecosystem. We documented the presence of the pathogen through all life stages of O. nubilalis (egg, larva, pupa, adult), by collecting throughout the crop season and examining each insect stage in the laboratory for the frequency of infection with N. pyrausta. The percentage of infection with N. pyrausta and magnitude of the O. nubilalis population fluctuated throughout generation 1 and generation 2. Both horizontal and vertical transmission played a role in maintaining N. pyrausta in the population in both generations. There were strong correlations between percentage adults with N. pyrausta and percentage larvae with N. pyrausta, and between percentage eggs with N. pyrausta and percentage larvae with N. pyrausta. There was a weak correlation between percentage adults with N. pyrausta and percentage eggs with N. pyrausta .T he percentage of insects infected with N. pyrausta was always lowest in the egg.
Yuri S Tokarev - One of the best experts on this subject based on the ideXlab platform.
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susceptibility of the gypsy moth lymantria dispar lepidoptera erebidae to Nosema pyrausta microsporidia Nosematidae
Insects, 2021Co-Authors: Anastasia G. Kononchuk, Anastasia N. Ignatieva, Vyacheslav V Martemyanov, Irina A Belousova, Maki N Inoue, Yuri S TokarevAbstract:The gypsy moth, Lymantria dispar, is a notorious forest defoliator, and various pathogens are known to act as natural regulators of its population density. As a widespread herbivore with a broad range of inhabited areas and host plants, it is potentially exposed to parasitic microorganisms from other insect hosts. In the present paper, we determined the susceptibility of gypsy moth larvae to the microsporidium Nosema pyrausta from the European corn borer, Ostrinia nubilalis. Gypsy moth samples from two localities of Western Siberia were used. N. pyrausta developed infections in the salivary gland and adipose tissue of gypsy moth prepupae and pupae, forming spore masses after 30 days of alimentary exposure to the second instar larvae. Among the experimental groups, the infection levels ranged from 0 to 9.5%. Effects of a covert baculovirus infection, phenylthiourea pretreatment and feeding insects on an artificial diet versus natural foliage were not significant in terms of microsporidia prevalence levels. Thus, L. dispar showed a low level of susceptibility to a non-specific microsporidium. It can be referred to as a resistant model host and not an appropriate substitute host for laboratory propagation of the microsporidium.
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Susceptibility of three species of the genus Ostrinia (Lepidoptera: Crambidae) to Nosema pyrausta (Microsporidia: Nosematida)
BIO Web of Conferences, 2020Co-Authors: I. V. Grushevaya, A. N. Ignatieva, Yuri S TokarevAbstract:Microsporidia are obligate intracellular parasites that affect the population density of many insect pests. In particular, infection with Nosema pyrausta is one of the major mortality factors for the European corn borer Ostrinia nubilalis , the Asian corn borer Ostrinia furnacalis and the adzuki bean borer Ostrinia scapulalis . The purpose of the work is to compare the susceptibility to N. pyrausta and pathogenesis of three species of moths of the genus Ostrinia . Studies conducted over 2 years have shown that in all three species of host insects under laboratory conditions, both during oral infection and transovarian transmission of infection (in the daughter generations of experimentally infected insects), only diplokaryotic spores formed corresponding to the main morphotype of the genus Nosema . Mean lethal time increased with instar of larvae used for infection but didn’t differ between the three species. The rates of transovarial transmission of N. pyrausta were also similar. Thus, all the insect species examined may equally participate in the parasite persistence in nature and serve as model laboratory hosts for parasitological research and mass propagation of the microsporidium.
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Greater wax moth Galleria mellonella (Lepidoptera: Pyralidae) as a resistant model host for Nosema pyrausta (Microsporidia: Nosematidae)
Journal of invertebrate pathology, 2018Co-Authors: Yuri S Tokarev, Ekaterina V. Grizanova, Anastasia N. Ignatieva, I. M. DubovskiyAbstract:Galleria mellonella fed 3 million Nosema pyrausta spores per larva showed 0 and 5% infestation rate at 30 °C and 24 °C, respectively. N. pyrausta virulence did not increase after passage through G. mellonella for three generations. When larvae were pretreated with phenylthiourea, Bacillus thuringiensis or combination of both, infection rates were 11%, 15% and 22%, respectively. Injection of untreated and potassium hydroxide-primed spores resulted in approximately 10% and 50% infection, respectively. G. mellonella is resistant to high dosages of N. pyrausta spores, serving as a prospective model of insect resistance to microsporidia, while host immunosuppression and/or spore activation increases success of the pathogen.
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Genetic polymorphism of natural isolates of Nosema pyrausta (Microsporidia: Nosematidae)
Ecological genetics, 2017Co-Authors: I. V. Grushevaya, J. M. Malysh, L. I. Trepashko, Yuri S Tokarev, Anastasia N. Ignatieva, Грушевая Инна Валентиновна, Игнатьева Анастасия Николаевна, Малыш Юлия Михайловна, Трепашко Людмила Ивановна, Токарев Юрий СергеевичAbstract:Background . Microsporidia are ubiquitous parasites of animals, most abundant in arthropods and fishes. Many species of these parasites are important from standpoints of medicine, veterinary and agriculture. Microsporidium Nosema pyrausta is an important disease agent in corn borer populations causing adverse effect on host fitness. Genotyping of this parasite is necessary for proper species identification and intraspecific polymorphysm studies. Materials and Methods. Microsporidia-infected larvae of corn borers of the genus Ostrinia were recovered from Krasnodar Territory in Russia and Gomel Region in Belarus. Small subunit ribosomal RNA (SSU rRNA) was amplified and sequenced directly, while intergenic spacer (IGS) was amplified, cloned and sequenced (1-5 clones per sample) for four isolates of microsporidia. Sequences were aligned and compared using standard bioinformatics tools (Clustal W and BLAST). Results . SSU rRNA genotyping showed allocation of all four isolates to N. pyrausta with 100% identity to each other and 99.7% similarity to Nosema bombycis , the type species of the genus Nosema. High levels of IGS sequence variation (61-74%) is observed both between isolates of different species and populations of microsporidia as well as between molecular clones within parasite isolates from individual hosts. Conclusion . N. pyrausta is widespread in corn borer populations and its genetic structure is complicated, as in other species of these parasites. Further studies of molecular markers are needed for genetic differentiation of geographic isolates of N. pyrausta .
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Redefinition of Nosema pyrausta (Perezia pyraustae Paillot 1927) basing upon ultrastructural and molecular phylogenetic studies
Parasitology research, 2015Co-Authors: Yuri S Tokarev, J. M. Malysh, Anastasia G. Kononchuk, Elena V. Seliverstova, Andrei N. Frolov, Irma V. IssiAbstract:Populations of European corn borer (Ostrinia nubilalis Hubner) from Krasnodar Territory (Southwestern Russia) become regularly infected with Nosema-like microsporidia. To identify the parasite, it was subjected to electron microscopy and small subunit ribosomal RNA (SSU rRNA) gene sequencing. The spore ultrastructure of the parasite was highly similar to Nosema bombycis from China and Nosema pyrausta from the USA. The nucleotide sequence of SSU rRNA gene was identical to a microsporidium isolated from O. nubilalis in southern France (GenBank accession no. HM566196) and closely related to Nosema bombycis (no. AY209011, 99.7 % sequence similarity) from Bombyx mori of Chinese origin and N. pyrausta (no. AY958071) from O. nubilalis of North American origin. As the molecular haplotype of SSU rRNA is fixed for the parasite infecting O. nubilalis across Europe and N. pyrausta was initially described in France as Perezia pyraustae (Paillot CR Acad Sci Paris 185: 673-675, 1927), we conclude that the parasite examined under the present study correspond to the type isolate of N. pyrausta. The microsporidium from O. nubilalis in North America (no. AY958071) corresponds therefore to a closely related, yet distinct haplotype.
Douglas V. Sumerford - One of the best experts on this subject based on the ideXlab platform.
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effects of infection with Nosema pyrausta on survival and development of offspring of laboratory selected bt resistant and bt susceptible european corn borers
Journal of Invertebrate Pathology, 2010Co-Authors: Miriam D Lopez, Leslie C. Lewis, Douglas V. SumerfordAbstract:Abstract Infection with Nosema pyrausta Paillot lengthens developmental period of Bt-susceptible Ostrinia nubilalis (Hubner) to a similar extent as feeding on Cry1Ab-incorporated diet in Cry1Ab-resistant O. nubilalis, and these two factors combined lengthen developmental period further than either alone. Resistant O. nubilalis mating with infected susceptible, or infected resistant partners would produce partially- and fully-resistant offspring, respectively, infected with N. pyrausta. To investigate the impacts on the progeny of such matings, test crosses were set up to produce partially- and fully Cry1Ab-resistant O. nubilalis offspring transovarially infected and not infected with N. pyrausta, which were exposed to Cry1Ab toxin at doses of 0, 3, or 30 ng/cm2 for 7 days. Transovarial infection with N. pyrausta significantly decreased 7 day survival of partially and fully-resistant O. nubilalis feeding on 30 ng/cm2 Cry1Ab. In addition, N. pyrausta infection delayed larval development (as measured by weight) of partially- and fully-resistant O. nubilalis feeding on 3 and 30 ng/cm2 Cry1Ab. Impacts of natural enemies on target pests may have the potential to impact evolution of resistance. N pyrausta-infected O. nubilalis are more strongly affected by feeding on Bt, and would be less likely to survive to adulthood to pass on resistance to the next generation. This indigenous microsporidium may work to delay evolution of resistance in O. nubilalis by lowering their ability to survive on Bt.
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Nosema pyrausta and cry1ab incorporated diet led to decreased survival and developmental delays in european corn borer
Entomologia Experimentalis Et Applicata, 2010Co-Authors: Miriam D Lopez, Douglas V. Sumerford, Leslie C. LewisAbstract:The high dose/refixge strategy for delaying evolution of resistance to Bt maize [Zea mays L. (Poaceae) ] relies on random mating between resistant European corn borers, Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae), and susceptible O. nubilalis from the refuge. However, differences in developmental rate caused by feeding on Bt maize, or infection with the microsporidium Nosema pyrausta Paillot (Microsporida: Nosematidae) may result in assortative mating. Developmental delays and mortality caused by infection with N. pyrausta and feeding on Bt maize were quantified alone and in combination in CrylAb-resistant and susceptible O. nubilalis. Feeding on Cry1Ab-incorporated diet significantly increased number of days from hatch to pupation and decreased survival in the resistant population. Infection with N. pyrausta increased mortality and lengthened development in both the resistant and susceptible populations. The combination of CrylAb-incorporated diet and infection with N. pyrausta in resistant O. nubilalis lengthened development and increased mortality to a greater extent than either factor alone. Greater larval delays of resistant O. nubilalis feeding on Bt maize could lead to temporal isolation from adults emerging from refuge maize. The resulting assortative mating would hasten the evolution of resistance. Developmental delays caused by infection with N. pyrausta may increase the likelihood of mating between resistant and infected susceptible adults emerging from refuge maize, producing infected offspring that are also more susceptible to Bt maize.
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Dynamics of Nosema pyrausta in natural populations of the European corn borer, Ostrinia nubilalis : A six-year study
Biocontrol, 2006Co-Authors: Leslie C. Lewis, Douglas V. Sumerford, Lori A. Bing, Robert D. GunnarsonAbstract:Nosema pyrausta (Paillot) (Microsporida: Nosematidae) is an obligatory intracellular parasite of the European corn borer, Ostrinia nubilalis (Hubner) (Lepi- doptera: Crambidae). This pathogen is maintained in natural populations of O. nubilalis by both horizontal and vertical transmission. The impact of N. pyrausta on fecundity of adults and survival of larvae has been well documented in laboratory and field research. In an extensive study covering a 6 year period at one site, we described the effect of N. pyrausta within O. nubilalis populations in a continuous corn following corn ecosystem. We documented the presence of the pathogen through all life stages of O. nubilalis (egg, larva, pupa, adult), by collecting throughout the crop season and examining each insect stage in the laboratory for the frequency of infection with N. pyrausta. The percentage of infection with N. pyrausta and magnitude of the O. nubilalis population fluctuated throughout generation 1 and generation 2. Both horizontal and vertical transmission played a role in maintaining N. pyrausta in the population in both generations. There were strong correlations between percentage adults with N. pyrausta and percentage larvae with N. pyrausta, and between percentage eggs with N. pyrausta and percentage larvae with N. pyrausta. There was a weak correlation between percentage adults with N. pyrausta and percentage eggs with N. pyrausta .T he percentage of insects infected with N. pyrausta was always lowest in the egg.
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Growth, development, and survival of Nosema pyrausta-infected European corn borers (Lepidoptera: Crambidae) reared on meridic diet and Cry1Ab.
Journal of economic entomology, 2004Co-Authors: Brendon James Reardon, Douglas V. Sumerford, Richard L. Hellmich, Leslie C. LewisAbstract:Transgenic corn, Zea mays L., hybrids expressing crystal protein endotoxin genes from Bacillus thuringiensis Berliner are an increasingly popular tactic for managing the European corn borer, Ostrinia nubilalis (Hubner), in North America. O. nubilalis populations also are often vulnerable to the ubiquitous entomopathogenic microsporidium Nosema pyrausta (Paillot). We examined the effect of feeding meridic diet incorporated with purified Cry1Ab on growth, development, and survival of Nosema-infected and uninfected neonate O. nubilalis. Infected larvae developed more slowly than uninfected larvae. Increasing the concentration of Cry1Ab in diet reduced larval development, and this effect was amplified by microsporidiosis. Infected larvae weighed significantly less than uninfected larvae. The relationship among Nosema infection, Cry1Ab concentration, and larval weight was fitted to an exponential function. The LC50 of infected larvae was one-third that of uninfected larvae, indicating that infected larvae are more vulnerable to toxin. This work has implications for resistance management of O. nubilalis and demonstrates that it is important to determine whether N. pyrausta is present when testing susceptibility of larvae to transgenic corn hybrids.
John J. Obrycki - One of the best experts on this subject based on the ideXlab platform.
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Selection of Nosema pyrausta (Microsporidia: Nosematidae)-infected Ostrinia nubilalis (Lepidoptera: Pyralidae) eggs for parasitization by Trichogramma nubilale (Hymenoptera: Trichogrammatidae)
Crop Protection, 1995Co-Authors: Mahmoud M.e. Saleh, Leslie C. Lewis, John J. ObryckiAbstract:Abstract Trichogramma nubilale Ertle and Davis females were offered a choice between egg masses of the European corn borer, Ostrinia nubilalis (Hubner), infected with the microsporidium Nosema pyrausta (Paillot) and non-infected egg masses. Nosema pyrausta -infected O. nubilalis eggs were smaller (weight) than non-infected host eggs. Trichogramma nubilale females did not discriminate between infected and N. pyrausta -free egg masses. This microsporidian infection did not significantly affect the sex ratio of emerging wasps. Significantly fewer and smaller adult parasitoids emerged from infected host eggs than from noninfected eggs.
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Behavior and Survival in Corn Plants of Ostrinia nubilalis (Lepidoptera: Pyralidae) Larvae When Infected with Nosema pyrausta (Microspora: Nosematidae) and Parasitized by Macrocentrus grandii (Hymenoptera: Braconidae)
Environmental Entomology, 1994Co-Authors: David B. Orr, Leslie C. Lewis, John J. ObryckiAbstract:To clarify the interaction among the European corn borer, Ostrinia nubilalis , the parasitic wasp, Macrocentrus grandii , and the entomopathogen Nosema pyrausta , we examined behavior and survival in corn stems of O. nubilalis larvae infected with N. pyrausta and parasitized by M. grandii. Fifty-four percent of heavily infected, parasitized O. nubilalis larvae emigrated from their tunnels before emergence of parasitoid larvae and did not reestablish on corn plants. One-third as many heavily infected host larvae as noninfected larvae remained in tunnels until parasitoid larval emergence. The tunnels bored by infected, parasitized O. nubilalis larvae did not differ in length from those of noninfected parasitized larvae, suggesting that emigration behavioral changes occur after feeding. Parasitoid larval and pupal mortalities were greater in infected O. nubilalis hosts than in noninfected hosts. Greater than 46% of heavily infected M. grandii broods wandered instead of remaining clustered around host carcasses and pupating. This behavior accounted for almost ≈40%of the observed mortality in infected parasitoids. Wandering was attributed to decreased production of cocoons by hosts, causing parasitoid larvae to search for suitable substrates on which to spin their own cocoons. Percentage emergence of M. grandii adults from corn stalks was significantly lower in N. pyrausta -infected treatments, but the sex ratio of the parasitoid was unaffected by the level of host infection. The mean number of M. grandii adults per brood was reduced from 39.8 in the noninfected treatment to 10.5 in heavily infected larvae.
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Modification of Herbivore and Parasitoid Behavior Over Three Trophic Levels by the Entomopathogen Nosema pyrausta (Microsporida: Nosematidae)
Annals of the Entomological Society of America, 1994Co-Authors: David B. Orr, Leslie C. Lewis, John J. ObryckiAbstract:Effects of the microsporidian Nosema pyrausta Paillot on behavior of the European corn borer, Ostrinia nubilalis (Hubner), and its parasitoid, Macrocentrus grandii Goidanich, were examined in the laboratory. Silk produced by O. nubilalis larvae around feeding and pupation sites was more frequently diffuse (cobweblike, unstructured) in diet cups containing N. pyrausta -infected larvae; however, frequency of diffuse silk production by O. nubilalis larvae was not influenced by M. grandii parasitism. We found no evidence of N. pyrausta spores in the silk produced by infected O. nubilalis larvae. Three O. nubilalis cocoon statuses were identified as follows: (1) complete cocoon, in which thick silk cocoon completely surrounded larvae or larval remains at O. nubilalis or M. grandii pupation; (2) incomplete cocoon, which was open on one or more sides at pupation; and (3) no cocoon at pupation. The percentage of O. nubilalis larvae that formed a complete cocoon or no cocoon was significantly influenced by both infection by N. pyrausta and parasitism by M. grandii. O. nubilalis larvae that had been either infected or parasitized displayed ≈7.2- and 12.3-fold increases in activity, respectively. Larvae that had been both infected and parasitized displayed a 45-fold increase in level of activity. Sixty-two to 80% of parasitoids emerging from hosts with an incomplete cocoon, and >91% emerging from no cocoon, were unable to spin their own cocoons, wandered from host carcasses, and did not pupate. The incidence of M. grandii spinning and wandering, and distance wandered, were independent of N. pyrausta dosage to which host larvae were exposed. Fully fed M. grandii larvae, which emerged from hosts that had not spun cocoons and were placed in complete cocoons, were able to pupate successfully and to emerge, regardless of infection status.
Regina G. Kleespies - One of the best experts on this subject based on the ideXlab platform.
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Pathogens of the European corn borer, Ostrinia nubilalis, with special regard to the microsporidium Nosema pyrausta
Journal of Pest Science, 2016Co-Authors: Gisbert Zimmermann, Alois M. Huger, Gustav A. Langenbruch, Regina G. KleespiesAbstract:The European corn borer, Ostrinia nubilalis , is the most important pest insect of corn ( Zea maize ) in Germany, other European countries and historically in North America. However, in Europe only a few reports on naturally occurring biotic mortality factors are available. In the present review, an overview on pathogens including nematodes attacking O. nubilalis is compiled. The primary data were originally derived from long-term diagnostic studies on pathogens of arthropods carried out by the Institute for Biological Control, Darmstadt, Germany. These are updated with findings from the literature and supplemented with data from other pest insects of the same lepidopterous Crambidae family. The most important and most frequently found pathogens are the microsporidium Nosema pyrausta , the fungi Beauveria bassiana and to some extent also Fusarium spp., and the bacteria Bacillus thuringiensis and Serratia marcescens . Thus far, viruses have not been detected. Data on practical use of B. thuringiensis , B. bassiana and other fungi, N. pyrausta , and some nematodes for biological control of O. nubilalis are presented. Because of the importance of N. pyrausta as a population regulator of O. nubilalis, causing a chronic disease in larvae and adults, the current knowledge on the occurrence, biology, transmission, effects on the host insect, interactions with beneficial insects and field experiments is presented. These data are complemented with former, unpublished studies on the occurrence and incidence of N. pyrausta in some German and French O. nubilalis populations (Hessen, Baden-Württemberg, Alsace). The review clearly indicates that pathogens may play an important role as naturally occurring mortality factors of O. nubilalis which may also be used as biocontrol agents or within conservation biological control strategies.
