POSSIBLE EVIDENCE OF NON-RANDOM MATING IN COTTON STAINER INSECTS FROM ST. THOMAS, USVI. Harold J. Grau, Dept. of BCES, Christopher Newport Univ., Newport News, Va.23606. The Insect genus Dysdercus (Pyrrhocoridae; Heteropte
ra) is known collectively as the cotton stainers because many of its species have feeding habits that include the transfer of a fiber-staining fungus to the cotton bolls they feed on. Other food sources include various Malvaceous plants. One New Worl
d species, D. andreae , inhabits most of the islands of the West Indies. On St. Thomas, US Virgin Islands, the species is found exclusively in association with Thespesia populnea trees, feeding on its seeds. Among the behaviors exhibited by these bugs
is prolonged copulation, in which mated pairs remain in copula for extended periods of time. It is not clear if mating in these insects is random. In random mating, one would expect to find that, if variation in body size exists among adults, there
should be no correlation among body sizes of mated adult males and females within a pair. Also, in a random mating system, there should be no difference in body sizes between unmated and mated adults. To examine whether the mating system of these insec
ts is random, body sizes of mated and unmated adult D. andreae were measured from several populations on St. Thomas, USVI. Three indicators of body size were used: pronotum width, wing length, and thorax-abdomen length. There was no significant dif
ference found in the body sizes of mated and unmated adults. However, statistically significant correlations were found among the measured body size indices of mated males and females, that is, larger males tended to be mated with larger females. These
results suggest that mating in this insect is not random, but based in part on size selection within a pair.
(Virginia Journal of Science vol. 46(2):93)
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hgrau@cnu.edu