Diurnal activity and seasonal incidence of mirid bug, Nesidiocoris tenuis (Reuter), on bottle gourd and its natural enemies in relation to weather parameters

Abstract

Bottle gourd, Lagenaria siceraria (Molina) Standley, is an important cucurbit crop often affected by insect pests. A field study was conducted during Kharif, 2024 at Horticulture Farm, Sri Karan Narendra College of Agriculture, Jobner, Jaipur, to assess the diurnal activity and seasonal incidence of the mirid bug, Nesidiocoris tenuis (Reuter), a major emerging pest of bottle gourd, and its natural enemies. The mirid bug, N. tenuis, exhibited clear diurnal activity, with the maximum abundance at noon, followed by afternoon and early morning and declining activity towards evening. Infestation on leaves began in the 33rd Standard Meteorological Week (SMW) (0.72 bugs/ five leaves per plant) and peaked in the 39th SMW (23.76 mirid bugs/five leaves per plant). Populations on flowers and fruits appeared during the 36th and 37th SMW and reached peaks in the 40th SMW (11.28 mirid bugs/ five flowers per plant) and in the 41st SMW (19.60 mirid bugs/ five fruits per plant), respectively. Natural enemies, mainly coccinellids and spiders, appeared from the 34th SMW, with peak populations of 3.76 and 5.72 per plant, respectively. Mirid bug incidence showed a significant positive correlation with maximum temperature and sunshine hours (p<0.05), while fruit infestation was negatively correlated with rainfall. The regression analysis indicated that abiotic factors explained 88.3- 93.3% of mirid bug population variability, highlighting maximum temperature as the most influential factor. The present study findings provide a basis for forecasting and sustainable management of N. tenuis in bottle gourd.