Proteins synthesized and secreted by larvae of the ectoparasitic wasp, Eulophus pennicornis

A microscopic examination of Eulophus pennicornis larvae on their host Laca nobia oleracea, revealed that peristaltic waves travelled from the anterior to posterior end of the feeding wasp larvae, and vice verse. In addition, when wasp larvae were immersed in PBS in vitro, they released a variety of proteins, with molecular weights ranging from (at least) 14 to 200 kDa. Amo ngst these was a protein with an estimated molecular weight similar to that of the 27 kDa parasitism-specific protein (PSP) detected in plasma from pa rasitized L. oleracea [Richards and Edwards, Insect Biochem Mol Biol 29:557 -569 (1999)]. Similar results were obtained when the wasp larvae were incub ated on balls of cotton wool soaked in tissue culture medium or sucrose, i. e., conditions that resemble their natural feeding behaviour. These results (and others) indicate that the wasp larvae release proteins, putatively th rough their mouth, Protein synthesis studies using S-35-methionine indicate d that the wasp larvae synthesize and secrete a variety of proteins in vitr o, including one with a molecular weight corresponding to that of the L. ol eracea 27 kDa PSP. As expected, only a portion of the total proteins synthe sized by the parasitoid larvae were subsequently secreted. In addition, the autoradiogram of secreted proteins contained significantly fewer bands tha n silver-stained SDS gels of proteins released into PBS or onto cotton wool . Thus, some of the additional bands detected on the latter gels are though t to represent proteins that were not of wasp origin. Instead, these protei ns released by the wasp larvae are speculated to be derived from their gut and, as such, probably represent proteins derived from host haemolymph and ingested during feeding. This possibility was supported by an electrophoret ic analysis of homogenate supernatants prepared from wasp larvae with or wi thout their gut contents. These studies indicated that the gut contents of the larval parasitoid contributes several distinct bands to the total prote in profile. The ability of E. pennicornis larvae to synthesize, secrete, an d release proteins is discussed with reference to those produced by endopar asitoid larvae. Published 2001 Wiley-Liss, Inc.(dagger)