HOST SELECTION, SEX ALLOCATION, AND HOST FEEDING BY METAPHYCUS-HELVOLUS (HYMENOPTERA, ENCYRTIDAE) ON SAISSETIA-OLEAE (HOMOPTERA, COCCIDAE) AND ITS EFFECT ON PARASITOID SIZE, SEX, AND QUALITY

Black scale, Saissetia oleae (Olivier), growth ceased following parasi tization by Metaphycus helvolus (Compere). With insectary-parasitized hosts, both male and female parasitoid size increased with increasing host size. Average host size in a laboratory study was larger and no c lear host-parasitoid size relationship resulted. The observed secondar y sex ratio from the laboratory study was 0.18 (male:total), whereas t he mean secondary sex ratio of offspring from hosts parasitized in a c ommercial insectary was 0.48. For both laboratory and insectary-parasi tized hosts, host scale size from which male offspring emerged was sig nificantly smaller than those from which females emerged. The effect o f parasitoid size on several measures of progeny reproductive fitness was examined under laboratory conditions. Larger parasitoids of both s exes had longer life spans, with male longevity more strongly affected by size than female longevity. Four-day egg complement was correlated with parasitoid size, with large females producing approximately twic e as many eggs as small females. Under competitive conditions (with 2 virgin males and 1 virgin female), large male parasitoids were 3 times as likely to contact the female first as were small males, and were 5 times as successful in copulating with the female. No significant dif ference existed between large and small males in the number of times t hey failed to copulate with a virgin female.