Differential Winter Mortality Relative to Sex in the Population of the Southern Green Stink Bug, Nezara viridula (Pentatomidae, Hemiptera)

Abstract

Most of the adults of the third generation of Nezara viridula pass the winter in the dense crowns of quickset hedge of Cryptomeria japonica, juniperus chinensis and in the crevice of leaves of Yucca recurvifolia. Mean mortality relative to different wintering quarters were 64.57 and 37.99%, 86.06, in cryptomeria, yucca and Chinese juniper, respectively. Survival rate of female adults was 11% higher than those of male. This differential mortality relative to sex alters the female ratio of the population is seen before and after hibernation from 48.3 to 54.4%. Validity of changes in sex ratio caused by the differential mortality of the sexes was also confirmed by the censuses conducted in a paddy field for the population before hibernation and in rape and wheat fields for the population after hibernation. Difference in mortality relative to the sorts of shelter becomes significant for the periphery population being largely depend its persistence upon the possibility of finding well protected wintering quarters. It is also important from the viewpoint of the dynamics of Nezara population that the loss caused by the winter mortality is somewhat balanced up by the differential mortality of the sexes which cames in favour of females. It was shown that the expected maximum rate of increase from the reproductive adults of the second generation to the hibernated adults of the third generation will be 2.15. © 1962, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.