A comparison of night-interruption on diapause-averting among two populations of the cotton bollworm,Helicoverpa armigera

Abstract

Photoperiodic time measurement in insects can be affected by interrupting the dark phase of the light dark cycle with short supplementary light pulses. All the photoperiodic responses tested are highly sensitive to night interruption, and the long night effect is reversed by a light break. Most past studies revealed two points of apparent light sensitivity (the so鄄 called A and B peaks) , but the response pattern varied considerably among different species. Some species had only one peak (or trough) , either A or B. Even the same species may have different patterns of response depending on the experimental conditions. However, it is still not clear whether differences exist in the effect of night鄄interruption on diapause鄄averting among different geographic populations. The cotton bollworm, Helicoverpa armigera (H俟bner) is one of the most serious crop pests in Asia, Australia, Africa and Europe. The species is distributed across much of China and