The Compatibility of Tebufenozide with a Laboratory Lepidopteran Host/Hymenopteran Parasitoid Population

The ecdysone agonist tebufenozide appears to be a lepidopteran-specific insect growth regulator that has no effect on ectoparasitic Hymenoptera and only affects endoparasitic Hymenoptera indirectly through its affect on the hostʹs physiology in laboratory tests.Hyssopus pallidus[Eulophidae] adults readily stung and oviposited on codling moth hosts that had slipped their head capsules forward after being fed an artificial diet containing up to 40 ppm (24 × LC50) tebufenozide, and their ectoparasitic progeny pupated. These eulophids were reared for five generations exclusively on hosts that were fed a high concentration of tebufenozide. Even an endoparasitoid,Ascogaster quadridentata,egressed from hosts fed an artificial diet containing 3× more tebufenozide (0.080 ppm) than the LC50for nonparasitized codling moth larvae. Time to adult parasitoid eclosion was not affected by host exposure to sublethal concentrations of tebufenozide. The LC50for diet containing tebufenozide fed to codling moth,Cydia pomonella,in their ultimate stadium was 0.025 ppm. Time to eclosion of moths was significantly (P< 0.04) shortened when larvae were exposed to sublethal amounts of tebufenozide, and female moths eclosed significantly (P< 0.04) earlier than males. Surviving female moths that eclosed from larvae fed >LC50concentration of the ecdysone agonist oviposited fewer viable eggs.