Thermotolerance and Heat-Shock Protein Gene Expression Patterns in Bemisia tabaci (Hemiptera: Aleyrodidae) Mediterranean in Relation to Developmental Stage.

Temperature plays an important role in the growth, development, and geographic distribution of insects. There is convincing evidence that heat-shock proteins (HSPs) play important roles in helping organisms adapt to thermal stress. To better understand the physiological and ecological influence of thermal stress on the different development stages of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mediterranean species (MED), nymphs and adults were shocked with temperatures of 35, 38, and 41℃ for 1 and 2 h, respectively, and the survival rate, fecundity, and developmental duration were investigated in the laboratory. The expression levels of the hsp40, hsp70, and hsp90 genes were assessed using real-time PCR. The results indicate that the survival rates of the nymphs and adults decreased with increased temperature. A 2-h heat shock at 41℃ induced a significant reduction in fecundity in adults and an increase in developmental duration in young nymphs. Hsp90 showed higher temperature responses to thermal stress than hsp40 or hsp70. The expression levels of the hsps in the adults were significantly down-regulated by a 2-h heat shock at 41℃ compared with that by a 1-h treatment. A significant decrease in the expression levels of the hsps also occurred in the adults when the temperature increased from 38 to 41℃ for the 2-h treatment, whereas no significant decrease occurred in the nymphs. Compared with previous studies, we provide some evidence indicating that MED has the potential to adapt to a wider temperature range than the Middle East-Asia Minor 1 species.