EFFECT OF HOST DENSITY ON OFFSPRING SEX-RATIOS AND BEHAVIORAL INTERACTIONS BETWEEN FEMALES IN THE PARASITOID WASP NASONIA-VITRIPENNIS (HYMENOPTERA, PTEROMALIDAE)
Bh. King et al., EFFECT OF HOST DENSITY ON OFFSPRING SEX-RATIOS AND BEHAVIORAL INTERACTIONS BETWEEN FEMALES IN THE PARASITOID WASP NASONIA-VITRIPENNIS (HYMENOPTERA, PTEROMALIDAE), Journal of insect behavior, 8(1), 1995, pp. 89-102
Pairs of females of the parasitoid wasp Nasonia vitripennis were video
taped with one or two hosts. The presence of an additional host decrea
sed the number of interactions between females but had no measured eff
ect on the nature of the interactions, i.e., on whether the interactio
n involved physical contact or occurred while one of the females was p
arasitizing a host. The number of hosts did not itself affect offsprin
g sex ratios but did influence which other factors were correlated wit
h sex ratio. When there was one host, the proportion of sons was more
positively correlated with utilization of previously drilled holes tha
n with female-female interactions, whereas when there were two hosts,
the reverse was true. Parasitizing an already parasitized host appeare
d to affect a female's sex ratio beyond any effects of the physical pr
esence of another female: When two hosts were present, the proportion
of sons was greater from hosts parasitized by both females than from h
osts parasitized by only one female. The observation that parasitizati
ons in previously drilled holes and female-female interactions are cor
related with sex ratios is consistent with previous studies; however,
that these relationships are host density dependent is a new result an
d remains unexplained.