AbstractA single choice test was performed to examine developmental strategies in the uniparental endoparasitoidMeteorus pulchricornisand its host, the cotton bollwormHelicoverpa armigera. The results support the dome-shaped model in which the fitness functions are ‘dome-shaped’ relative to size (and age) of host at parasitism. Older and, hence, larger host larvae were simply not better hosts for the developing parasitoids. Although parasitoid size (measured as cocoon weight and adult hind tibia length) was positively correlated with host instars at parasitism, parasitoids developing in larger hosts (L5and L6) suffered much higher mortality than conspecifics developing in smaller hosts (L2–L4). Furthermore, egg-to-adult development time inM. pulchricorniswas significantly longer in older host larvae (L4–L6) than in the younger. Performance ofM. pulchricornis, as indicated by fitness-related traits, strongly suggests that the L3host is the most suitable for survival, growth and development of the parasitoid, followed by both L2and L4hosts; whereas, L1, L5and L6are the least favourable hosts. The oviposition tendency ofM. pulchricornis, represented by parasitism level, was not perfectly consistent with the performance of the offspring; L2–L4hosts, although with the same parasitism level, had offspring parasitoids with differences in fitness-related performance. Larval development inHelicoverpa armigerawas usually suspended, but occasionally advanced, in the final instar.
Data of in vitro synthesized dsRNAs on growth and development of Helicoverpa armigera
