Integration of Zoophthora radicans and synthetic female sex pheromone for the control of diamondback moth

The widespread fungal pathogen Zoophthora radicans kills both adult and larval stages of the diamondback moth. At IACR-Rothamsted, a novel strategy for diamondback moth control, based upon a fast entry/ slow exit trap containing the female sex pheromone and the pathogen, is under development. Male moths are attracted into an inoculation chamber where they are showered with infective conidia of Z. radicans. On habituation to the pheromone, they leave the trap and re-enter the crop, passively vectoring conidia to other susceptible adults and larvae and creating further foci of infection when they succumb to disease. In field (Cameron Highlands, Malaysia) and laboratory trials, moths were attracted to the trap at all times of the day, spent long enough in the trap to acquire a lethal infection and were killed by Z. radicans infection within their demonstrated longevity in the field. The influence of rain, sunlight and temperature on conidial persistence was also evaluated. At high doses Z. radicans is pathogenic to the parasitoid Diadegma semiclausum but not to Cotesia plutellae. This physiological susceptibility is unlikely to translate into susceptibility in the field. Neither parasitoid vectored Z. radicans conidia to susceptible larvae but host movement evoked by D. semiclausum foraging rendered larvae more likely to encounter infective conidia.