Spatial field survey of cotton whitefly and its pupal parasitism in relation to temperature and humidity in Southern Pakistan

Abstract

Among abiotic factors, temperature and relative humidity are important factors for higher cotton yields in all cotton growing regions. Cotton whitefly (Bemisia tabaci G.) being vector of CLCuV in Pakistani cotton crop is responsible to cause an economic damage. A survey of whitefly populations and its parasitism with connection to temperature and relative humidity was conducted in fourteen cotton growing districts of Sindh province (southern Pakistan) for 2012 and 2013 seasons. There was a significant difference in whitefly population and percent parasitism among the fourteen districts. The highest average whitefly populationof two consecutive years was recorded in Khaipur, Sukhur, Sangar and Nausharo Feroze i.e. 7.5, 6.1, 5.6 and 5.5 individuals per leaf, respectively. While the lowest was recorded in Hyderabad (1.9) and Mirpurkhas (2.2). On the other hand, the highest percent parasitism was observed in Khaipur, Tando Muhammad Khan, Nausharo Feroze and Sangar i.e. 14.1, 10.5, 10.4 and 10.5 percent, respectively whereas the lowest percent parasitism was recorded in Hyderabad (5.8) and Matiari (5.9). The study regarding impact of abiotic factors on whitefly population and percent parasitism was carried out at Central Cotton Research Institute Sakrand in 2013. We observed positive relationship between the abundance of whitefly and percent parasitism; while both had a strong positive relationship with percent relative humidity and only a positive relationship with the average temperature. This study hopes to establish an understanding for cotton growers and researchers that how population of whitefly and its parasitism vary in relationship with abiotic factors among different cotton growing areas of Sindh province. Furthermore, this study could help in forecasting and monitoring of whitefly incidence and its parasitism.