Life Cycles, Diapause and Developmental Characteristics in Subtropical Locusts, Nomadacris succincta and N. japonica (Orthoptera : Acrididae)

Two species of locusts, Nomadacris succincta and N. japonica, are morphologically similar to each other and occur sympatrically in Okinawa, but they could be separated easily by using combinations of morphometrical traits including hind femur length, head width, and elytron length. Their development, reproduction, and metabolism were compared under controlled conditions. Eggs of both species hatched without entering diapause. Eggs of N. japonica had a lower level of lower thermal threshold and a higher thermal constant than N. succincta. Nymphal development of N. japonica was faster at a short photoperiod than at a long one, while N. succincta, which grew faster than the other species, showed no photoperiodic response in nymphal development. Adults of both species remained sexually immature for a long time, presumably owing to diapause. However, adults of N. succincta started ovipositing much earlier when transferred from a short to a long photoperiod at adult emergence than when reared continuously under the same conditions both as nymphs and adults. In N. japonica, no oviposition was observed under any of the above conditions. Respiration rates of adults depended not only on the reproductive state but also on the body size and sex.