Influence of egg load and oviposition time interval on the host discrimination and offspring survival of Anagyrus pseudococci (Hymenoptera : Encyrtidae), a solitary endoparasitoid of citrus mealybug, Planococcus citri (Hemiptera : Pseudococcidae)

Oviposition and host discrimination behaviour of unmated Anagyrus pseudococ ci (Girault), an endoparasitoid of the citrus mealybug Planococcus citri (R isso), were investigated in the laboratory. Female parasitoids were able to discriminate between parasitized hosts and healthy ones. The mean number o f ovipositions was significantly higher in unparasitized than in parasitize d hosts. Conspecific-superparasitism occurred more often than self-superpar asitism. Changes in consecutive ovipositions over three hours by A. pseudoc occi suggested that egg load influenced the discrimination behaviour of the parasitoids, with females which had low egg loads mostly avoiding oviposit ion in already parasitized hosts at time intervals ranging from 0 h to 96 h , and distributing their eggs in the high quality (unparasitized) hosts. Th e parasitized hosts were rejected more commonly through antennal perception of external markers than during ovipositor probing which could have encoun tered internal markers but this relationship changed with increasing time a fter oviposition. The parasitoid's oviposition rate in unparasitized and co nspecific-parasitized hosts varied at the different oviposition time interv als when the females had fewer eggs in the ovaries. Percentage emergence of parasitized offspring was not significantly influenced by whether they dev eloped in single or superparasitized mealybugs. The significance of host di scrimination by A. pseudococci is discussed.