Pesticidi i Fitomedicina (Jan 2006)
Effect of Temperature on Imago Life Span, Fecundity and Reproduction Rate of Greenhouse Whitefly (T. vaporariorum W.)
Abstract
Imago life span, fecundity and survival rate of the different developmental stages and average abundance of female offspring of greenhouse whitefly (Trialeurodes vaporariorum) were studied at three constant (18, 22 and 27°C) and one alternating (18/7°C) temperature.Temperature highs are inversely proportionate to imago life span. Temperature increase from 18/7°C to 27°C decreased the whitefly life span 3.3-fold. Under 18°C and 22°C, whitefly laid eggs most abundantly (147 and 126, respectively), while fecundity decreased under lower and higher temperatures. Half the offspring of the investigated whitefly laboratory strain (49.5%) were males, which resulted in lower values of reproduction and growth rates of the whitefly strain.Optimum development of greenhouse whitefly was achieved at 18°C, which is evident from a maximum number of eggs laid and highest average number of potential and actual female offspring (68.2 and 58.3, respectively), compared to the other investigated temperatures.The consequence of a 50.8-day long true generation time is evident from the low values of growth capacity (0.074) and intrinsic rate of increase (0.080). With temperature increasing to 22°C and 27°C, the period of whitefly oviposition showed a tendency to decrease further on. Higher temperatures reduced the total abundance of eggs laid and, consequently, the abundance of potential and actual female offspring, but increased growth rate.
