Divergent life histories between wild and commercially-sourced Cotesia flavipes (Hymenoptera: Braconidae): Does continuous rearing on a single host affect potential host range?

Moths of the genus Diatraea Guilding (Lepidoptera: Crambidae) are stalk-boring pests of sugarcane. In Colombia, the economically important species are D. busckella, D. indigenella, D. saccharalis, and D. tabernella. Augmentative releases of the gregarious endoparasitoid Cotesia flavipes (Cameron) are used to manage this pest complex. We compared the performance of two C. flavipes populations, one field-collected, and one commercially-sourced, on all four hosts, hypothesizing lower performance of the commercial population on species other than D. saccharalis due to continuous rearing on this species. Parasitism success did not vary with parasitoid source, but varied among host species, being highest in D. indigenella and lowest in D. tabernella. Sex ratio was female-biased, averaging 0.635, and did not vary with parasitoid source or host species. Wild wasps developed more slowly than commercial wasps on all hosts. Both parasitoid populations produced their largest broods in D. indigenella, but commercial wasps produced smaller broods than wild wasps in D. busckella and D. tabernella, and substantially lower weight gain of host larvae post-parasitism, suggesting impaired host regulation ability. In all hosts, wild wasps produced larger female progeny, based on wing area, than commercial wasps. When all metrics of parasitoid performance (fitness) were combined into a single index, D. indigenella was the most suitable host for both parasitoid populations. Both parasitoid sources performed similarly on D. saccharalis, whereas wild wasps performed better on all other Diatraea species. Thus, the inadvertant consequences of artificial selection in cultures of gregarious endoparasitoids may include faster development and smaller body size.