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INDIVIDUAL SEX RATIO ADJUSTMENT IN RESPONSE TO THE OPERATIONAL SEX RATIO IN THE SOUTHERN GREEN STINKBUG
Denson Kelly McLain1, Nancy Brannen Marsh1
1Department of Biology, Landrum Box 8042, Georgia Southern College, Statesboro, GA, 30460.
Abstract:
Females of the southern green stinkbug, Nezara viridula (Hemiptera: Pentatomidae), initiating copulation in a female-biased environment produced relatively more sons than females initiating copulation in a male-biased environment. Although families suffering greater mortality yielded more sons, the difference in offspring sex ratio between treatments was not due to differential mortality by sex since the distribution of family size did not vary between treatments. Female condition, indexed by female size and size of the first egg mass laid, did not vary between treatments and, therefore, apparently did not contribute to the results. Thus, it appears that the stinkbug is capable of facultative sex ratio adjustment in response to the operational sex ratio, increasing the production of sons when males are rare. In nature, overlapping generations and female-biased operational sex ratios may occur; conditions under which selection for sex ratio adjustment is most intense.
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