INTERACTION OF VENOMS WITH THE CALYX FLUIDS OF 3 PARASITOIDS, CARDIOCHILES-NIGRICEPS, MICROPLITIS-CROCEIPES (HYMENOPTERA, BRACONIDAE), AND CAMPOLETIS-SONORENSIS (HYMENOPTERA, ICHNEUMONIDAE) IN EFFECTING A DELAY IN THE PUPATION OF HELIOTHIS-VIRESCENS (LEPIDOPTERA, NOCTUIDAE)

Calyx fluid (polydnavirus) from Cardiochiles nigriceps Viereck requires fluid from the venom gland and reservoir to inhibit host pupation. The pupation of all hosts injected with C. nigriceps calyx fluid mixed with C. nigriceps venom were either inhibited or became larval-pupal intermediates. In contrast, the calyx fluid of C. nigriceps mixed with the venom of either Microplitis croceipes (Cresson) or Campoletis sonorensis (Cameron) was unable to inhibit host pupation, although all three species successfully parasitize the same host. Through high-performance liquid chromatography, the synergistic component of C. nigriceps venom was found to be a 66-kDa (kilodalton) protein. In our studies, the calyx fluid of M. croceipes mixed with M. croceipes venom prolonged the larval stage of the Heliothis virescens (F.) for a few days, but all injected host larvae pupated, which suggests that another factor is needed to inhibit pupation with the M. croceipes-H. virescens system. The venom of either C. nigriceps or C. sonorensis did not alter the effect of M. croceipes calyx fluid on H. virescens development.