DefinePK

Abstract

A study was conducted to test the hypothesis that Diadegma semiclausum is one of the factors involved in horizontal transmission of the microsporidial disease of the diamondback moth DBM, Plutella xylostella L. Results showed that 41 of the larvae exposed to presumably microsporidia contaminated the adult D. semiclausum died before pupation, and all of the dead larvae were observed to have abundant microsporidia spores. None of the DBM larvae in the control treatment died before pupation. The microsporidia spores were detected on the body of the parasitoid adults D. semiclausum of both sexes, indicating that the parasitoid get contaminated with spores during eclosion or host finding bout. The spores were also detected within parasitoids body abdomen of both sexes, and within the sex organ of the adult parasitoid female. This suggests that parasitoid is infected with the disease during immature stages. The presence of spores within female sex organ plus ovipositor could explain why many larvae died before pupation as the parasitoid oviposition parasitism behaviour indirectly transmit the disease spore to the host DBM larvae.