Demographic response to constant temperatures in Neoseiulus barkeri (Phytoseiidae) fed on Tetranychus urticae (Tetranychidae)

The effect of temperature on survivorship, reproduction, adult longevity, population growth parameters, fecundity and sex ratio of the predatory mite Neoseiulus barkeri Hughes fed on nymphal stages of Tetranychus urticae Koch was determined at seven constant temperatures of 15, 20, 25, 27, 30, 35 and 37ºC. Fitting adult survival data to Weibull frequency distribution indicated that the adult survival curve was type I at all temperatures tested, which means most deaths occurred among older individuals. The values of the life table entropy at the temperature range of 15–37°C (H < 0.5) correspond to type I Slobodkin's survivorship curve. The oviposition period and female and male adult longevity decreased as temperature increased from 15 to 37ºC. The highest value of the net reproductive rate (R0) was 22.02 females/female at 25ºC.The longest and shortest female longevity were 86.28 and 20.5 days at 15 and 37°C, respectively. Furthermore, the highest and lowest values of the intrinsic rate of increase (rm) were 0.256 and 0.036 females/female/day at 30 and 15ºC, respectively. The relationship between temperature and rm of N. barkeri was modeled and critical temperatures including Tmin, Topt and Tmax for intrinsic rate of increase were estimated at 13.51, 32.20 and 39.92°C, respectively using the Lactin 2 model. Moreover, the mean generation time (T) decreased significantly from 47.18 to 8.51 days with increasing temperature from 15°C to 37°C. The shortest and longest doubling times (DT) were 2.71 and 19.16 at 30°C and 15°C, respectively. The results of this study indicated that N. barkeri has inherent potential for the control of two-spotted spider mite at higher temperatures especially at temperatures between 30–35ºC.