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
1996
Lampson, L.J. | Morse, J.G. | Luck, R.F.
Black scale, Saissetia oleae (Olivier), growth ceased following parasitization 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 clear host-parasitoid size relationship resulted. The observed secondary sex ratio from the laboratory study was 0.18 (male:total), whereas the mean secondary sex ratio of offspring born hosts parasitized in a commercial insectary was 0.48. For both laboratory and insectary-parasitized hosts, host scale size from which male offspring emerged was significantly smaller than those from which females emerged. The effect of parasitoid size on several measures of progeny reproductive fitness was examined under laboratory conditions. Larger parasitoids of both sexes 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 twice as many eggs as small females. Under competitive conditions (with 2 virgin males and (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 difference existed between large and small males in the number of times they failed to copulate with a virgin female.
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