STADIUM-SPECIFIC DEGENERATION OF HOST PROTHORACIC GLANDS BY CAMPOLETIS-SONORENSIS CALYX FLUID AND ITS ASSOCIATION WITH HOST ECDYSTEROID TITERS

Campoletis sonorensis is a polydnavirus-carrying wasp that parasitizes Heliothis virescens larvae, Previous studies indicated that C. sonore nsis polydnavirus (CsPDV) induces degeneration of host prothoracic gla nds when injected into last-stadium hosts. Degeneration also occurs wh en last instars are naturally parasitized, but it is not observed in h osts parasitized as penultimate instars, This study investigated the e ffect of CsPDV on the development of penultimate-stadium hosts and the temporal sensitivity of H. virescens prothoracic glands to virally-in duced degeneration. We found that calyx fluid (containing CsPDV) cause d degeneration of host prothoracic glands when injected into newly-ecd ysed, penultimate-stadium hosts, but degeneration was delayed until in jected larvae reached the critical head capsule size for the last stad ium, even when injected larvae exhibited supernumerary molts, Host pro thoracic glands became sensitive to virally-induced gland degeneration just prior to apolysis to the last larval/larval molt, simultaneous w ith an ecdysteroid peak, Prothoracic gland degeneration in response to calyx fluid was also noted in two other hosts of C. sonorensis, Helic overpa tea and Spodoptera exiguae.