Population Dynamics and Weather Associations of Major Sucking Pests on Capsicum (Capsicum annuum L.) Varieties under Protected Cultivation

Abstract

Protected cultivation of capsicum provides a suitable microclimate for plant growth coupled with the proliferation of major sucking pests, including aphids, thrips and whiteflies. Scientific data on the seasonal abundance of these pests and their correlation with abiotic factors under protected conditions remain insufficient. The present study was conducted to assess the population dynamics of major sucking pests on two capsicum hybrids under protected cultivation and to estimate the influence of weather parameters on their populations. Under protected cultivation, biweekly observations on aphid (Aphis gossypii), thrips (Scirtothrips dorsalis) and whitefly (Bemisia tabaci) were documented on two capsicum hybrids (Kaveri 254 and Indra). Analysis of variance (ANOVA) was employed to analyse population dynamics, while Pearson's correlation and simple linear regression analyses were performed to examine the association between prevailing weather parameters and pest populations. The populations of sucking pests varied significantly among Standard Meteorological Weeks, with peak populations occurring between the 50th and 52nd SMWs prior to decreasing towards the end of the study period. The capsicum variety Kaveri 254 favoured higher aphid and thrips populations than Indra; in contrast, the whitefly populations were equivalent between the two varieties. Maximum temperature displayed significant negative correlations with all three sucking pests, while evening relative humidity showed a strong positive association with the whitefly population (r=0.918). Simple linear regression reinforced maximum temperature as the key factor impacting aphid (R²=0.713) and thrips (R²=0.533) populations, whereas evening relative humidity explained the highest proportion of variation in the whitefly population (R² = 0.843).  The study identified clear seasonal variation in the population dynamics of major sucking pests in capsicum under protected cultivation, with Indra displaying relatively lower susceptibility to aphids and thrips than Kaveri 254. Maximum temperature was recognised as the key weather parameter controlling sucking pest populations, whereas evening relative humidity proved to be the key factor for the whitefly population. These findings present a useful basis for designing weather-assisted pest monitoring and forecasting protocols contributing to sustainable insect pest management in capsicum under protected cultivation.