Seasonal abundance of potato pests in relation to environmental factors.
The effect of climatic factors on the phenology of foliage pests of potato was studied in Orissa, India, during the kharif and rabi seasons of 1983-84 and 1984-85. In both seasons, the potato crop was attacked by the aphids Aphis gossypii and Myzus persicae, the chrysomelid Chalaenosoma metallicum, the cicadellid Amrasca biguttula, the coccinellid Henosepilachna viginctioctopunctata [Epilachna vigintioctopunctata], the thrips Thrips flavus, the tarsonemid Polyphagotarsonemus latus and the noctuid Agrotis ipsilon. However, the phenology of the pests and the intensity of their attack varied considerably in the different seasons. Correlation analysis between various meteorological variables and the incidence of the different pest species during the kharif season revealed that temperature was significantly correlated with the incidence of most of the insect pests, except A. ipsilon. Population development of A. ipsilon was significantly influenced by temperature during the rabi season. Relative humidity was positively correlated with the incidence of T. flavus, P. latus and A. gossypii only. The only effect rainfall had on the phenology of the pests was on A. biguttula duing the rabi season.