Reproductive diapause and quiescence in a tropical rice bug, Leptocorisa oratorius

Experiments were carried out to analyze the effects of food supply and photoperiod on the induction of dormancy in Leptocorisa oratorius Fabricius (Heteroptera: Alydidae) adults in Alor Setar (latitude 6.1° N), West Malaysia. When the adults were deprived of food, they ceased oviposition, became tolerant to starvation, and their oxygen consumption rate decreased, but they did not accumulate lipid. Their oxygen consumption rate again increased when they were allowed to resume feeding. Therefore, food limitation induced quiescence in the adult. On the other hand, diapause was induced by short daylength (critical photoperiod was 12L:12D), leading to immature ovaries, hypertrophied fat bodies, lipid accumulation and low oxygen consumption rate even when food was available. However, in the study area most of the bugs probably did not enter diapause at any time of the year, because the shortest outdoor daylength including civil twilight was longer than the critical daylength for diapause induction.