Developing extreme heat acclimation in Bemisia tabaci Mediterranean (Hemiptera: Aleyrodidae).

Bemisia tabaci Mediterranean (MED) is a highly invasive cryptic species complex found in the world's tropical, subtropical, and temperate regions. It is a severe pest of various crops and a vector of plant pathogenic viruses, particularly geminiviruses. Thermal acclimation of insects is a critical for the survival in unfavorable temperature condition. We observed that great survival rate of B. tabaci MED at the uncontrolled greenhouse which had fluctuating temperature condition (FTC) from 10°C to 60°C in spring and summer season. Our study showed that while B. tabaci MED reared under FTC for 10 weeks from April to June, its survival rate was gradually increased when heat shock was treated 50°C for 0.5 h. In contrast, the same heat shock treatment was lethal in the colony reared under constant temperature condition (CTC) at the controlled insectary. After being acclimated, the lethal temperatures LT 50 , LT 95 , and LT 100 under CTC were 47.7°C, 50.1°C, and 50.3°C, whereas those under FTC were 59.8°C, 62.7°C, and 63.0°C, respectively. In addition, we observed that the transcript levels of three investigated heat shock protein (HSP) genes (hsp20, hsp70, and hsp90) were lower under FTC than under CTC. This study suggests that B. tabaci MED retains high heat acclimation ability, making it tolerant of extreme thermal conditions.