Temperature and Photoperiodic Effects on Induction and Termination of Diapause in Female Leptocorisa chinensis (Hemiptera: Alydidae)

Abstract

Abstract The effects of temperature and photoperiod on diapause induction and termination in Leptocorisa chinensis Dallas (Hemiptera: Alydidae) were studied under constant conditions or by using transfer experimental protocols. Nymphs were reared either under a long-day (16:8 [L:D] h) or a short-day (12:12 [L:D] h) photoperiod at 25°C in the laboratory. Females oviposited at 25 and 20°C under the long-day photoperiod. However, females did not lay eggs within 100 d at 15°C under the long-day photoperiod or at 20 and 15°C under short-day conditions. At 25°C, when nymphs were reared under a long-day photoperiod and transferred to a short-day photoperiod on the day of adult emergence, females started oviposition in 10 d but stopped shortly thereafter. When nymphs were reared under a short-day photoperiod and transferred to a long-day photoperiod on the day of adult emergence, females started oviposition in ≈40 d. Females that had been transferred from the field on 1 February and 29 March to long-day laboratory conditions at 25°C started oviposition in ≈40 d. However, females that had overwintered in the field were transferred to a short-day photoperiod at 25°C on 1 February and 29 March did not start oviposition in the laboratory. Both the nymphal and adult stages of L. chinensis are considered to be sensitive to reproductive diapause induction and termination signals both before and after overwintering. Female L. chinensis require not only a long-day photoperiod and >40 d at temperature of 20°C or higher but also threshold temperatures for start of oviposition, even after the winter.