The Influence of Rainfall Deficits on the Abundance of Helicoverpa (=Heliothis) armigera in Andhra Pradesh, India

Analysis of larval counts, light-trap data and weather patterns over a six year period shows that prolonged rainfall deficits promote the growth of Helicoverpa armigera populations in Andhra Pradesh, India. Drought stress resulting from rainfall shortages enhances the chemical cues involved in larval host selection behaviour and improves the nutritional quality of many wild and cultivated host plants on which this polyphagous pest reproduces. A more holistic analysis of the causes of H. armigera outbreaks should also include the effects of man induced drought that stem from the destabilisation of the water cycle in the drylands of India. Water conservation measures may need to be integrated in an overall plan of insect control on an area-wide basis.