Population dynamics of citrus whitefly, Dialeurodes citri (Ashmead) on Citrus reticulate (Mandarin) var. Kinnow as influenced by weather conditions

Abstract

A field study on population dynamics of citrus whitefly, Dialeurodes citri (Ashmead) on citrus mandarin (var. Kinnow) was carried out during 2014-15 at Centre of Excellence (COE) for Fruits situated in village Mangiana of district Sirsa, Haryana. The population of nymphs and adults of this pest was recorded from March 2014 to February 2015 at weekly interval. The nymphal population of the pest was observed only between 12th to 47th meteorological standard weeks (SW) with two major peaks i.e. one during 16th SW with a population of 83.44 nymphs/ 20 leaves and the second during 40th SW with a population of 133.22 nymphs/20 leaves. The above said population dynamics confirmed that this pest remained inactive in pupal stage during winter i.e. 48th to 11th SW. Similar trend was observed in respect of adult population. Nymphal population showed significant positive correlation with morning relative humidity (r = 0.329) and sunshine hours (r = 0.362), while adult population was found to have positive correlation with sunshine hours only (r = 0.332). Multiple regression analysis of the pest population with environment variables indicated that out of 45 per cent variability in nymphal population, 37 per cent was due to relative humidity and sunshine hours. Out of the total variability of 30 per cent variation in adult population, 20 per cent was due to evening relative humidity, while 10 per cent attributed to sunshine hours. The other weather parameters were found to have no significant correlation with the pest population. Although study of population dynamics of this study were conducted elsewhere but this is first study of its kind in the state of Haryana. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL). The information on population dynamics of any insect pest in a given ecological niche should be considered as starting point for evolving eco - friendly pest management package.