Seasonal incidence of two-spotted spider mite, Tetranychus urticae Koch infesting okra

Abstract

The mite population ranged from 0.70 to 14.45 mites/2 cm² of leaf area. Initially, during the 36th standard meteorological week (3rd WAG), the population was at 0.70 mites/2 cm² of leaf area. Mite population reached at its peak during the 43rd standard meteorological week (10th WAG) at 14.45 mites/2 cm² of leaf area. Subsequently, pest activity declined during the 44th standard meteorological week (11th WAG). The mite population continued to decrease each week, reaching lowest population during the 49th standard meteorological week (16th WAG) with a pest activity level of 4.15 mites/2 cm² of leaf area when the last picking was completed. The correlation study between the incidence of okra mites and weather parameters revealed highly significant negative correlations with morning relative humidity (r = -0.768), evening relative humidity (r = -0.841), mean relative humidity (r = -0.838), wind speed (r = -0.774), and vapor pressure (r = -0.649, -0.795). However, it showed a significant positive correlation with maximum temperature (r = 0.574) and bright sunshine hours (r = 0.607). Weather parameters such as minimum temperature, mean temperature, rainfall, and rainy days demonstrated non-significant negative correlations with the mite population (r = -0.509, -0.087, -0.289, -0.406, respectively).