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)
Ks. Islam et Mjw. Copland, 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), B ENT RES, 90(1), 2000, pp. 69-75
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.