Effects of Temperature and Photoperiod on Wing Form Determination and Reproduction of Thrips nigropilosus Uzel (Thysanoptera: Thripidae)

Abstract

Females of Thrips nigropilosus Uzel were reared at 18°C and 15L-9D from egg to prepupa, and then transferred to 4 experimental conditions: 18°C and 15L-9D; 18°C and 10L-14D; 25°C and 15L-9D; and 25°C and 10L-14D. The numbers of eggs subsequently laid by the females were counted, and the sex and wing form of their offspring were determined. Under the 4 conditions, only males were produced by virgin females, while both sexes were produced by once-mated females. Male offspring were all brachypterous. Female offspring were macropterous at both 18°C and 25°C and 15L-9D, brachypterous at 18°C and 10L-14D, and macropterous, brachypterous and intermediate at 25°C and 10L-14D. These results suggested that long-day photoperiods lead to the occurrence of the macropterous female and short-day photoperiods induce the development of the brachypterous female, and that high temperatures partly inhibit the development of the brachypterous female. The total number of eggs laid per female was significantly lower at 18°C and 10L-14D than at any other conditions. This indicated that moderate temperature and short-day photoperiod partly suppress the reproduction of the female thrips. © 1993, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.