Host stage selection and sex allocation by Anagyrus mangicola (Hymenoptera: encyrtidae), a parasitoid of the mango mealybug, Rastrococcus invadens (Homoptera: pseudococcidae)

Abstract

Host stage selection and sex allocation behaviors by Anagyrus mangicola Noyes were studied in choice and no-choice experiments in the laboratory. All host instars of the mango mealybug (MM), Rastrococcus invadens Williams (Hem., Pseudococcidae), were parasitized. First instars were less often encountered, seldom stung, and parasitized. They were, however, preferred for host feeding. Handling time per host decreased with increasing host size. Female wasps recognized previously parasitized hosts and, in cases where they attacked them, did not oviposit into them. The sex ratio of emerging parasitoids, expressed as proportion of males, was lowest when MM were parasitized as mature adult females and increased with decreasing host size, from young adult females to first instars. Female wasps emerging from any size of host were always larger than the corresponding males. Male size increased with that of the host, while female size was independent of host instar at oviposition. The possible impact of A. mangicola as a complementary natural enemy to Gyranusoidea tebygi Noyes (Hym., Encyrtidae), for the biological control of MM, is discussed.