Seasonal incidence and population dynamics of diamondback moth, Plutella xylostella (L.) on cabbage under semi-arid conditions of Rajasthan

Abstract

The present study, entitled “Population dynamics of diamondback moth, Plutella xylostella (Linn.) on cabbage, Brassica oleracea var. capitata”, was carried out during the Rabi seasons of 2021–22 and 2022–23 at the Research Farm of the Rajasthan Agricultural Research Institute. The objective was to examine the seasonal incidence of the diamondback moth and its relationship with prevailing abiotic factors under semi-arid conditions of Rajasthan. The findings revealed that the pest first appeared in the first week of December (49^th Standard Meteorological Week) in both crop seasons, with initial populations of 0.50 and 0.40 larvae per plant in 2021–22 and 2022–23, respectively. The larval population gradually increased, reaching a peak of 4.60 larvae per plant in the first week of February during 2021–22, and 4.90 larvae per plant in the last week of January during 2022–23. Thereafter, the population declined as the crop approached maturity and harvest. Correlation analysis showed a significant positive association between minimum temperature and larval population (r = 0.634 in 2021–22 and r = 0.517 in 2022–23). In contrast, maximum temperature, relative humidity, and rainfall exhibited non-significant negative correlations with pest incidence. The study concluded that mild minimum temperatures favored the development and multiplication of P. xylostella on cabbage under semi-arid agro-climatic conditions. These insights are valuable for forecasting pest incidence and devising effective management strategies against the diamondback moth in cabbage cultivation.