Production of early expressed parasitism-specific proteins in alternate sphingid hosts of the braconid wasp Cotesia congregata.

Parasitism of Manduca sexta larvae by the braconid wasp Cotesia congregata or injection of C. congregata polydnavirus (CcPDV) causes numerous alterations in host physiology, including developmental arrest, abrogation of host immunity, and the production of three abundant early expressed proteins (EP1, EP2, and EP3) that are secreted in large amounts into the host's hemolymph. Here we compare the levels of these proteins present in the hemolymph of three other sphingid species that vary in their compatibility for C. congregata. Hyles lineata was found to be permissive for C. congregata and EP1, EP2, and EP3 were present in larval hemolymph at levels comparable to those found in hemolymph from parasitized M. sexta larvae. By contrast, the lowest levels of EP proteins were found in hemolymph from parasitized Pachysphinx occidentalis larvae and this species was found to be completely refractory, since C. congregata eggs were invariably encapsulated. Parasitism of Sphinx vashti by C. congregata resulted in moderate levels of EP production. While the observed immune response was incomplete and some encapsulation of C. congregata eggs and/or larvae was observed, low numbers of S. vashti nevertheless were able to complete their development and emerge as adults. Thus, a correlation was established between host compatibility and induction of synthesis of the three parasitism-specific proteins, although the linkage between quantitative levels of EP production and the extent of encapsulation was variable. Copyright 1998 Academic Press.