The effects of the entomopathogenic nematode Steinernema carpocapsae on the Colorado potato beetle (CPB) Leptinotarsa decemlineata and the involvement of adipokinetic hormone (AKH) in the responsive reactions were examined in this study. It was observed that nematode application doubled the amount of AKH (Peram-CAH-I and Peram-CAH-II) in the central nervous system of L. decemlineata, indicating mobilization of anti-stress reactions in the body. Furthermore, the external co-application of Peram-CAH-II with the nematode significantly increased beetle mortality (5.6 and 1.8 times, 1 and 2 days after application, respectively). The mechanism underlying this phenomenon was investigated. As the effect on gut characteristics was equivocal, it was assumed that the nematodes profited from the observed mobilization of metabolites from the fat body into the Peram-CAH-II-induced hemolymph. This phenomenon supplied nematodes with a more nutrient-dense substrate on which they propagated. Furthermore, Peram-CAH-II lowered vitellogenin expression in the fat body, particularly in males, thus limiting the anti-pathogen defense capacity of the protein. However, there could be other possible mechanisms underpinning this chain of events. The findings could be theoretically intriguing but could also aid in developing real insect pest control methods in the future.

Institute of Entomology Biology Centre CAS Branišovská 31 370 05 České Budějovice Czech Republic

Institute of Entomology Biology Centre CAS Branišovská 31 370 05 České Budějovice Czech Republic; Faculty of Science University of South Bohemia Branišovská 31a 370 05 České Budějovice Czech Republic

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Six-year monitoring of pesticide resistance in the Colorado potato beetle (Leptinotarsa decemlineata Say) during a neonicotinoid restriction period

Unusual functions of insect vitellogenins: minireview