Influence of mating and oviposition behavior on progeny production of the ichneumonid parasitoid, Campoletis chlorideae uri icon

abstract

  • The Campoletis chlorideae Uchida is an important natural enemy of the noctuids, being the most important larval parasitoid of Helicoverpa armigera (Hubner) in different agro-ecosystem. Regulation of sex ratio in the hymenopterans has an important bearing on the use of natural enemies for the management of insect pests. There is no clear concept of sex ratio manipulation by C. chlorideae, therefore the present studies were conducted to understand the mechanism of sex ratio in C. chlorideae in 4 different mating schemes. Mating and parasitization regimes had a significant influence on the fecundity of C. chlorideae females, while no significant differences were observed for cocoon formation, adult emergence, and larval and pupal periods across mating regimes. There was a positive correlation (r = 0.68) between fecundity and longevity of C. chlorideae females. Attraction of more males to copulating pair resulted in mating of a female with two or three males simultaneously, suggested increased release of sex pheromone by the females during copulation and the competition among the males for mating. However, mating with multiple males simultaneously is not an additive advantage in progeny production, since only 20% of the C. chlorideae females (mated with two males) were able to parasitize the H. armigera larvae successfully. There was no consistent trend in sex ratio across treatments and parasitization days, except in case of unmated females. Studies on sexual and ovipositional behaviors suggested that extrachromosomal factors could be responsible for sex-determination in C. chlorideae, which needs to be tested systematically

publication date

  • 2009