Analysis of the Biology, Population Dynamics, Natural Enemies and Impact of the Groundnut Leaf Miner, Aproaerema modicella (Deventer) (I..epidoptera:Gelechiidae), on Groundnut in India

Abstract

The groundnut leaf miner (GLM), Aproaerema modicella (Deventer)(Lepidoptera: Gelechiidae) is a serious pest of groundnut and soybean throughout South Asia . Laboratory and field experiments were conducted over a two year period at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)in peninsular India to collect biological and 'ecological data necessary for developing a systems model for groundnut. Laboratory studies showed that temperature strongly influenced development and fecundity rates, egg and larval survivorship and adult longevity. A function describing the effect of temperature and female age on per capita GLM fecundity was fitted to laboratory data. GLM has five instars in India, and the larvae Larval populations fluctuated dramatically in field studies over four seasons, and no correlation was found to climatic factors.Simulated rainfall did not increase egg or larval mortality. Outbreak populations appear to be triggered by large scale adult immigration. Lower populations were found in resistant require ca. 180 mm2 of leaf area to complete development variety and insecticide plots. The late season, rapid decline in GLM density was likely a result of natural enemies Observed high GLM population in the 1987 rainy season reduced groundnut growth and yield in plants not protected with insecticides. Leaf mass was 33% lower, and stem and pod mass 30% lowerin unsprayed plants relative to sprayed plants. In addition, flower and peg production was lower in plants defoliated by GLM A large number of natural enemies attack GLM in the ICRISAT area, and among them are nine primary parasitoids. In addition,a fungal and viral pathogen were found. Less than 10% of GLMlarvae sampled in the field survived to the adult stage. The plant and GLM data collected in field and laboratory experiments were summarized in a pre -existing, generalized metabolic pool model. This model was used to simulate growth and development of the groundnut plant as well as the population dynamics of GLM