Analysing Climate-driven Shifts in Pest Phenology and Crop Damage in Jamun

Abstract

Jamun (Syzygium cumini Skeels) is an underexploited indigenous fruit tree of India valued for its nutritional and medicinal properties. This study assessed the seasonal incidence of major insect pests and natural enemies of jamun and examined their associations with weather parameters in Periyakulam and Andipatti blocks of Theni district, Tamil Nadu, during 2023–2024. A fixed-plot survey was conducted using ten randomly selected trees, with weekly monitoring of pest populations, damage, natural enemies, and weather variables obtained from an Automatic Weather Station. Correlation and regression analyses were performed using DSAASTAT. At Periyakulam, whiteflies, fruit flies, and gall insects showed positive associations with average temperature, whereas several pest groups showed negative associations with rainfall, relative humidity, or wind speed. At Andipatti, leaf miner incidence was positively associated with relative humidity and negatively associated with average temperature, rainfall, and wind speed. Leaf twisting weevil, helmet caterpillar, gall insect, whitefly, and fruit fly incidences were positively associated with average temperature. Fruit fly incidence was greatest during periods of high rainfall and humidity. The observed differences between the two locations indicate that weather–pest relationships varied among pest taxa and sites. The findings provide baseline information on seasonal pest occurrence, crop damage, natural-enemy activity, and weather associations in jamun-growing areas of Tamil Nadu.