Meeting Abstract
Parasitic wasps are highly diverse and play a major role in suppression of herbivorous pest populations. Prior work demonstrates that the gregarious endoparasitoid, Cotesia congregata, contains two incipient species originating from different host-foodplant complex sources, Manduca sexta on tobacco (MsT) and Ceratomia catalpae on catalpa (CcC). Hybrids resulting from CcC male x MsT female crosses are typically sterile. Bracoviruses (BVs) are endosymbionts of braconid wasps that facilitate wasp development by interrupting the immune responses and physiology of parasitized caterpillar hosts. BVs are integrated within the wasp genome and transmitted vertically. BV particles are injected during oviposition, where their encoded virulence genes are expressed in host tissues. Cumulative results to date indicate that some BVs are functional within a limited range of hosts. Several C. congregata BV (CcBV) genes differ between MsT and CcC wasps. We compared patterns of relative expression of selected CcBV genes in M. sexta and C. catalpae parasitized by individual MsT or CcC wasps, and in M. sexta parasitized by individual MsT and CcC hybrids, using qRT-PCR. Patterns of in vivo expression of CcBV genes from MsT and CcC wasps differed in each host species; a few genes were not detected in hosts parasitized by CcC wasps. Parasitization by sterile hybrids resulted in low or absent expression of CcBV genes. Results further support designation of the two host-foodplant complex sources of C. congregata as incipient species.
