Tomato yellow leaf curl virus (TYLCV) and its vector insect, the sweet potato whitefly Bemisia tabaci, are major threats to tomato and pepper production in all around world. Since the last three decades, both B. tabaci and TYLCV have been invaded into many countries via different routes. Our studies showed that various geminiviruses including TYLCV can be transmissible by seeds as well as whiteflies. Furthermore, commercially developed resistant tomato strains against TYLCV infection can serve as TYLCV reservoirs and potentially influence on TYLCV epidemics. Therefore, transmission pathways through both insect vectors and seeds should be concerned for suitable management of geminiviruses and whiteflies.

Vector-borne plant virus transmission is a complex mechanism. Plant viruses modify development and behavior of vectorinsects in a positive, negative, or neutral manner. Bemisia tabaci transmits Tomato yellow leaf curl virus (TYLCV) whichis a virus that seriously damaged tomato cultivars all around the world. We compared several behavioral and physiologicalcharacteristics between non-viruliferous (NV) and TYLCV-viruliferous (V) of 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 stressby increasing hsp mRNA levels but higher in mortality by either heat or cold shocks. Further, V whiteflies increasedthe rates of plant sap probing and light attraction behaviors than NV ones. Our results provide insights to understandvector’s role in relation to the acquisition and transmission of plant viruses.

Acquisition of plant viruses has various effects on physiological mechanisms in vector insects. Bemisia tabaci is the only known vector of Tomato yellow leaf curl virus (TYLCV), which is a serious virus affecting tomato cultivars. In this study, the lifespan of Q1 biotype was compared between non-viruliferous (NV) and TYLCV-viruliferous (V) whiteflies. Total lifespan from egg to adult death of NV whiteflies was 62.54 days but 10.64 days shorter in V whiteflies. We investigated the temperature susceptibility of B. tabaciby comparing mortalities as well as heat shock protein (hsp) mRNA levels between NV and V whiteflies. For this, NV and V whiteflies were exposed for either 1 or 3 h at 4, 25, and 35 °C. The mortality of V whiteflies was higher than NV ones following exposure at either 4 or 35 °C, but there was no significant difference at 25 °C. Analysis of the expression level of heat shock protein (hsp) genes using quantitative real-time PCR showed that both cold and heat shock treatments stimulated higher expression of hsps (hsp40, hsp70, and hsp90) at various rates in V whiteflies than NV ones, but there was no difference at 25 °C. All together, our results show that TYLCV acquisition accelerated the developmental rate and increased susceptibility to thermal stress in B. tabaci. Therefore, this modification may result in reduced vector longevity due to increased metabolic energy utilization. Our results provide insights into the complex interaction between vector fitness and thermal stress in relation to the acquisition and transmission of plant viruses.

Recently, several significant plant virus diseases have devastated various crops in agricultural fields of Korea, These virus disease are mostly transmitted and spread by vector insects, such as rice stripe virus (RSV) transmitted by planthopper Laodelphax striatellus, tomato spotted wilted virus (TSWV) by thrips Frankliniella occidentalis and tomato yellow leaf curl virus (TYLCV) by whitefly Bemisia tabaci. Insects as vectors are significantly important for the control of plant disease as well as insect themselves. Here, on the view of insects, interactive mechanisms of vector insect and plant pathogens were discussed on the system of TYLCV and B. tabaci. When insects acquisited virus they would be beneficial, neutral or detrimental. Generally, plant virus are ingested into the mouse and move from the gut to hemolymph and back to salivary gland. During this movement there would be numerous molecular interactions at a vector-virus specific mode. In addition, virus acquisition change vector's physiological and developmental states including longevity, fecundity and dispersal behavior. However, these interactive mechanisms of vector insects with plant virus are largely under investigated. B. tabaci is genetically diverse and transmit many begomoviruses including TYLCV. I demonstrated effects of TYLCV acquisition on fecundity, thermal response, endosymbiont profile and gene expression of B. tabaci.