Influence of weather parameters on the seasonal incidence of Lablab bean leafminer: Liriomyza spp. (Agromyzidae: Diptera)

This study explores the seasonal incidence, symptomatology and impact of leafminer (Liriomyza spp.) infestation on lablab (Lablab purpureus (L.) Sweet) crop in Tamil Nadu, providing valuable insights into the pests’ behaviour and the resulting crop damage. The objective was to assess infestation levels, damage and environmental factors affecting pest behaviour using surveys, correlation and regression analyses. Infestation levels varied significantly, ranging from 20 % to 84 %, with Salem and Erode experiencing lower levels and other districts showing higher infestations. The infestation was higher (84 %) in the Elavadai region of Dharmapuri district and lower (20 %) in the Thathampatti region of Salem district. The highest infestation levels were recorded in February, March and June 2023, with a noticeable decline observed in August and October. The larval mining caused extensive crop damage, significantly impairing photosynthetic efficiency and triggering premature leaf drop. A correlation analysis revealed a strong negative relationship between infestation levels and temperature extremes, indicating that temperature plays a crucial role in pest dynamics. At the same time, relative humidity and rainfall had minimal influence on leafminer incidence. Further regression analysis demonstrated that weather factors accounted for 32.8 % of the variability in infestation levels. The results underscore the importance of understanding seasonal patterns in leafminer occurrence within lablab ecosystems. This knowledge is essential for devising effective integrated pest management strategies supported by field surveys, pest prediction models and molecular techniques. Farmers can effectively manage leafminer infestations and enhance lablab yields by adopting these methods while mitigating the challenges of the global climate.