Seasonal pattern of pests and predator activity in tomato ecosystem

An investigation was conducted over two consecutive years (Rabi 2023-24 and 2024-25) to study the temporal pattern of insect pests and natural enemies activity and their relationship with weather parameters. The study focused on key pests; fruit borer (Helicoverpa armigera), whitefly (Bemisia tabaci), aphid (Aphis gossypii) and jassid (Amrasca biguttula biguttula) as well as their natural enemies, primarily Coccinellids. The fruit borer was first observed during the 43rd Standard Meteorological Week (SMW) with an initial mean population of 0.06±0.06 larvae per plant, peaking at 3.52±0.42 larvae per plant in the 52nd SMW. Whiteflies first appeared in the 42nd SMW with an initial population of 1.99±0.46 individuals per three leaves, peaking at 15.16±13.38 individuals in the 51st SMW. Aphids were initially recorded at 1.15±1.15 individuals per three leaves during the 42nd SMW, reaching a peak of 5.06±2.08 in the 51st SMW. Jassids emerged during the 42nd SMW with a mean population of 1.48±0.62 individuals, peaking at 6.49±2.71 individuals per three leaves in the 50th SMW. Natural enemies such as Coccinellids were first seen in the 42nd SMW and a peak population (1.99±0.81 individuals per plant) observed in the 49th SMW. Correlation analysis revealed that fruit borer populations were significantly and negatively correlated with maximum (r = -0.787**) and minimum (r = -0.734**) temperatures while positively and significantly associated with morning relative humidity (r = 0.637**). Whitefly showed a significant negative correlation with maximum (r = -0.436*) and minimum (r = -0.549*) temperatures. Aphids also displayed substantial negative correlations with maximum (r = -0.579**) and minimum (r = -0.708**) temperatures and had a strong positive correlation with Coccinellids (r = 0.895**), indicating a predator-prey relationship. Jassids showed a significant negative correlation with evening relative humidity (r = -0.496*), while other weather parameters showed non-significant associations. The multiple regression analysis revealed that maximum temperature (°C), minimum temperature (°C), morning relative humidity (%), evening relative humidity (%), rainfall (mm) together influenced to an extent of 73.50 (R2=0.735), 54.80 (R2=0.548), 85.10 (R2=0.851) and 63.20 (R2=0.632) per cent of fruit borer, whitefly, aphid and jassid population, respectively.