The sweetpotato whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is a disastrous pest in horticultural plants worldwide. B. tabaci is a species complex including at least 24 biotypes in the world. In Korea, B-biotype has been invaded in 1998, Q-biotype in 2005 and widely spread into the country. B. tabaci is also a vector of more than 100 plant viruses, especially begomoviruses. Since 2008, Tomato yellow leaf curl virus (TYLCV) has been invaded into Korea and severely damaged tomato cultivar in all over of the country. B. tabaci is the only vector insect of TYLCV. Here we demonstrated whether TYLCV influence on the vector physiology during virus transmission. Pesticide susceptibility of whiteflies on TYLCV acquisition was determined in B. tabaci using the two-layered parafilm feeding chamber which containing 20% sugar solution including different doses of imidacloprid. Our result showed that TYLCV-viruliferous whiteflies were more susceptible to imidacloprid ingestion than non-viruliferous whiteflies. This study suggests that plant virus can manipulate the physiological conditions of vector insects.

Vector-borne plant virus transmission is a complex mechanism involving various interactions of viruses, vectors and plants. Plant viruses modify, either directly or indirectly, the rates of development, reproduction and behavior of vector insects in a positive, negative, or neutral manner. The sweetpotato whitefly, Bemisia tabaci, is the only known vector of Tomato Yellow Leaf Curl Virus (TYLCV) which is a virus that seriously damaged tomato cultivars all around the world. Acquisition of TYLCV influences on various developmental, physiological and molecular mechanisms of Q1 biotype B. tabaci. We compared several behavioral and physiological characteristics between non-viruliferous (NV) and TYLCV-viruliferous (V) of Q1 biotype whiteflies. When B. tabaci acquired TYLCV, total life span was shorter and fecundity was lower than NV ones. V whiteflies were more susceptible to thermal stress by increasing hsp mRNA levels but higher in mortality by either heat or cold shocks. Furthermore, V whiteflies increased the rates of plant sap probing and light attraction behaviors than NV ones. All together, our results show that TYLCV acquisition regulates B. tabaci to enhance the rates of development and environmental susceptibility. Our results provide insights to understand vector’s role in relation to the acquisition and transmission of plant viruses.

The sweetpotato whitefly, Bemisia tabaci, is a vector of more than 100 plantdiseased viruses as well as a serious pest to various horticultural crops. Virus acquisition affects the vector’s development and reproduction, but its mechanism is largely unknown. Here we compared the temperature responses between non-viruliferous and TYLCV-viruliferous Q biotype of B. tabaci. When both non-viruliferous and viruliferous whiteflies were exposed for 1 and 3 h at 4, 25, and 35°C, the mortality rate of viruliferous whiteflies is higher than nonviruliferous after exposure at 4°C and 35°C, but no differences at 25°C between them. Analysis of the expression levels of heat shock protein (hsp) genes using the quantitative realtime PCR showed that viruliferous whiteflies has higher expression in hsp70, and hsp90 at both 4°C and 35°C, but no differences at 25°C. The results suggest that vector insects may not be durable to unfavorable temperature conditions when they acquisite plant viruses.