Differential variation in development of the B- and Q-biotypes of Bemisia tabaci (Homoptera: Aleyrodidae) on sweet pepper at constant temperatures

Abstract

Developmental rates of the B- and Q-biotypes of Bemisia tabaci (Gennadius, 1889) were studied at seven constant temperatures (17, 20, 23, 26, 30, 33, and 35°C) on sweet pepper, Capsicum annuum L. ('Morrón'). The egg incubation period and the rimes required to complete development at all immature stages decreased with increasing temperature up to 33°C, but at 35°C were found to be greater than at 33°C. The relationships between developmental rate of B. tabaci and temperature were influenced by the insect biotype. The lower and upper developmental thresholds as well as the optimal temperatures and thermal constant for the preoviposition period and all immature stages were estimated by fitting the observed developmental rates versus temperature with a nonlinear model and two linear models. For all stages, graphs obtained by plotting the reciprocal of development times against temperature could be described by the modification 2 of the Logan's model. The simple linear model tT = K+ct suffices for predicting B- and Q-biotype phenologies on sweet pepper for the temperature range of 17-33°C. The shortest developmental times as well as the lowest developmental thresholds and thermal constant were mostly obtained with the Q-biotype. Overall, the most favorable temperature range appeared to be 31-33°C. Mean generation times (adult-adult) ranged from 17 d (Q-biotype) and 18 d (B-biotype) at 33°C to 49 d (B-biotype) and 46 d (Q-biotype) at 17°C.