Photoperiodic Control of Adult Diapause in a Subtropical Katydid, Euconocephalus pallidus REDTENBACHER(Orthoptera:Tettigoniidae)

Abstract

Euconocephalus pallidus from the subtropical island of Okinawa, Japan, matured after six nymphal instars. The nymphal duration did not vary with photoperiod in a range from 11L-13D to 15L-9D at 25°C. Adults took about 25 days to start ovipositing in long day conditions (14L-10D and 15L-9D) and more than 60 days in short day conditions (11L-13D to 13L-11D). The adult stage immediately after emergence was the most sensitive to photoperiod, and the pre-oviposition period was also influenced by the photoperiod experienced during the nymphal stage. Female adults transferred from a short day to a long day laid eggs without delay. It seems that the adults of the 1st generation, having grown under long day conditions, avert diapause, while those of the 2nd generation, having experienced short day conditions, enter diapause. Thus, it is likely that E. pallidus has a heterodynamic life cycle controlled by photoperiod in the subtropical region.