Effect of temperature on biological parameters of cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Abstract

The whitefly, Bemisia tabaci is a highly polyphagous and most damaging insect pest of cotton and many other economically important crops throughout the world. Recently in India, whitefly threat is increasing in cotton crop. North Indian cotton growing belt experienced severe outbreak of this pests during 2014–15 causing huge yield losses. With the changing climate scenario and the polyphagous trait of B. tabaci, its infestation may quickly spread over other regions of the world. In the present study, a temperature-based phenology model is developed for B. tabaci by rearing it on cotton leaves under laboratory conditions (growth chamber) at six constant temperatures (15–37 °C). The developmental rates and survivorship of immature life stages and reproductive parameters of adult life stages of B. tabaci were estimated by fitting various non-linear mathematical equations to the temperature-dependent development data obtained in laboratory. A cohort updating and rate summation approach was employed in stochastic simulation of life table parameters at different test temperatures. The study revealed that development time decreased with increase in temperature within the evaluation range of temperatures. The life cycle of B. tabaci was shortest at 32 °C with the shortest mean development time (30 days) and the longest development time (63 days) was obtained at 17 °C. The optimum developmental temperatures predicted for various immature life stages of B. tabaci were: 20.4, 18.03, 26.83, 26.83 and 22.93 °C for egg, nymph1, nymph2, nymph3 and pseudopupa, respectively. Wang model fits well to estimate temperature-dependent mortality of B. tabaci life stages. The mortality was lower at 32 °C and higher at 37 °C. The favourable temperature range that supported optimum reproductive fitness of B. tabaci was observed to be 22–32 °C.