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
Lj. Lampson et al., 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, Environmental entomology, 25(2), 1996, pp. 283-294
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.