Impact of weather parameters and planting dates on the population dynamics of key insect pests and natural enemies in onion cultivation

This study aimed to explore the relationship between weather parameters and the dynamics of insect pests and natural enemies in rabi onion cultivation. Significant correlations were observed for enemies Onion thrips T. tabaci, tobacco caterpillar Spodoptera litura, and cricket Gryllus campestris populations with maximum temperature (0.829, 0.70, and 0.56, respectively). T. tabaci exhibited a significant negative correlation with morning relative humidity, while both T. tabaci and S. litura showed negative correlations with evening relative humidity. The cricket population demonstrated a significant positive correlation with minimum temperature, rainfall, and wind speed. No significant correlation was found between different weather parameters and the populations of natural enemies. Furthermore, our investigated the temporal dynamics of thrips populations corresponding to each transplanting date. The first transplanting revealed an incidence of 16.11 thrips/plant, followed by 19.91 thrips/plant for the second transplanting and 22.91 thrips/plant for the third transplanting.