Our model system includes the endoparasitic braconid wasp, Microplitis croceipes , and a lepidopteran larval host, Heliothis virescens . Several days following parasitization the host experiences developmental arrest. We know that the host experiences altered respiration, reduced accumulation of nutrient stores, changes in hemolymph chemistry and hormonal balance, etc. We have discovered that teratocytes from the extra-embryonic membrane of the parasitoid egg, in the absence of a parasitoid larva, cause many of the symptoms observed in parasitized larvae. Our current research shows that polypeptide secretions from the teratocytes inhibit protein synthesis in specific tissues of the host in some still undefined manner.
Evidence suggests that a post translational event is affected.
We have isolated a polypeptide, and the gene responsible for encoding it, that has biological activity. We know the amino acid sequence and cDNA nucleotide sequence for this peptide and have expressed it in a baculovirus expression system with the product showing biological activity. We hope to use the information gained from these studies to develop alternative forms of insect management. N.E. Beckage, S.N. Thompson and B.A. Federici, eds. Down-regulation of juvenile hormone esterase and arylphorin production in Heliothis virescens larvae parasitized by Microplitis croceipes.