Divergent life histories between wild and commercially-sourced Cotesia flavipes (Hymenoptera: Braconidae) parasitizing four species of Diatraea (Lepidoptera: Crambidae)

Moths of the genus Diatraea Guilding (Lepidoptera: Crambidae) are stalk-boring pests of sugarcane throughout the neotropics. 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 one tactic used to manage this pest complex. We compared the laboratory performance of two C. flavipes populations, one field-collected, and one commercially-sourced, on all four host species, hypothesizing lower performance of the commercial population on host 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, with other species intermediate. 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, being slowest on D. tabernella, whereas commercial wasps were slowest on D. busckella. 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 host species, 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 of host suitability, D. indigenella was the most suitable host for both parasitoid populations. Both parasitoid sources had similar performance on D. saccharalis, the host used to rear the commercial population, whereas wild wasps performed better on all other Diatraea species. The inadvertant consequences of artificial selection in mass-reared cultures of gregarious endoparasitoids are discussed, specifically the evolution of faster development and smaller body size.