none 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. Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Abiotic factors; Physical factors; Land and freshwater zones; Oriental region; India Helicoverpa armigera (Noctuidae); Food plants; Quality, rainfall & population dynamics relationships; Hymenopteran parasites; Campoletis chlorideae; Prevalence related to rainfall; Population dynamics; Rainfall relationships; Aridity; Drought influence on population dynamics; Climate and weather; Rainfall influence on population dynamics; Andhra Pradesh; Patancheru; Population dynamics related to rainfall, mechanisms Campoletis chlorideae (Ichneumonidae); Lepidopteran hosts; Helicoverpa armigera; Prevalence related to rainfall; Climate and weather; Rainfall influence on prevalence, lepidopteran host; Andhra Pradesh; Patancheru; Prevalence in lepidopteran host, influence of rainfall