MICROCHAROPS-ANTICARSIAE (HYM, ICHNEUMONIDAE), PARASITOID OF ANTICARSIA-GEMMATALIS (LEP, NOCTUIDAE) - HOST AGE PREFERENCE, SEX-RATIO EFFECTS AND FUNCTIONAL-RESPONSE

The endoparasite, Microcharops anticarsiae Gupta, is one of the natura l control agents of Anticarsia gemmatalis Hubner. The effects of host age on the levels of parasitisation and the sex ratio of the subsequen t progeny, together with the functional response of M. anticarsiae at 6 different host densities, were evaluated experimentally. In choice e xperiments involving two or four consecutive instars, female parasitoi ds showed no preference for host larvae of a particular age. The sex r atio of the parasitoids was affected by the host instar in which they developed (G3df = 18.21, p < .001). Parasitoid sex ratio was most skew ed towards females in parasitoid larvae that developed in 4th instar h osts. A type II functional response was exhibited by the female parasi toid in response to host density. Information on the sex ratio, indica ted the best host instar to parasitize to produce an optimum female: m ale sex ratio, while the functional response indicated the average rat e (38.0 +/- 7.5) of parasitism per female. This information is importa nt for mass-rearing of M. anticarsiae, for biological control programs against A. gemmatalis.