Acceptance and suitability of four lepidopteran stemborers for the development of the pupal parasitoid Xanthopimpla stemmator (Hymenoptera: Ichneumonidae).
Xanthopimpla stemmator, a solitary endoparasitoid of lepidopteran stem borer pupae, was recently imported into East Africa as a candidate biological control agent of gramineous stem borers. Suitability of Busseola fusca, Chilo partellus, Eldana saccharina and Sesamia calamistis, for the development of X. stemmator was studied in the laboratory. One- to six-day-old laboratory reared pupae of the four stem borer species were exposed to naive X. stemmator females. All host pupae and ages were acceptable for oviposition. The parasitoids inflicted multiple probe wounds on 67.8% of pupae exposed. B. fusca, C. partellus and S. calamistis were equally suitable with 56.4, 59.4 and 52.3%, respectively, of probed pupae leading to emergence of adult parasitoids. E. saccharina was less suitable with only 22.6% of probed pupae producing parasitoids. Emergence of parasitoids did not differ significantly across the six pupal ages for B. fusca and S. calamistis, but varied for C. partellus and E. saccharina. No parasitoids emerged from 6-day-old E. saccharina pupae. Realized fecundity of females reared on the four stem borer pupae showed that fewer progeny were produced by females emerging from E. saccharina than females reared on the other three stem borer species. Eldana saccharina may be a poor host for X. stemmator in Kenya, but this parasitoid is a potential candidate for biological control of B. fusca, C. partellus and S. calamistis.