Upregulation of temperature susceptibility in Bemisia tabaci upon acquisition of Tomato yellow leaf curl virus (TYLCV) Joseph Carlo A. Pusag a , S.M. Hemayet Jahan a , Kwan-Suk Lee c , Sukchan Lee b , Kyeong-Yeoll Lee a,⇑ a School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea b Department of Genetic Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea c National Institutes of Agricultural Science, Suwon 441-707, Republic of Korea article info Article history: Received 20 April 2012 Received in revised form 11 July 2012 Accepted 16 July 2012 Available online xxxx Keywords: Bemisia tabaci Heat shock proteins Plant virus TYLCV Whitefly abstract 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. tabaci by 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 signif- icant difference at 25 °C. Analysis of the expression level of heat shock protein (hsp) genes using quanti- tative 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 com- plex interaction between vector fitness and thermal stress in relation to the acquisition and transmission of plant viruses. Ó 2012 Published by Elsevier Ltd. 1. Introduction Vector-borne plant virus transmission is a complex mechanism involving various combinations of viruses, vectors, and plants (Rubinstein and Czosnek, 1997; McKenzie, 2002; Jiu et al., 2007). Very often, the transmission of plant viruses is mediated by arthro- pod vectors including insects. Further, plant viruses modify, either directly or indirectly, the rates of development, reproduction, and behavior of vector insects in a positive, negative, or neutral man- ner. Positive modification of vectors occurs through various indi- rect plant-mediated interactions. For example, aphids are more attracted to virus-infected plants displaying visual stimuli such as yellowing leaves (Fereres et al., 1999; Hodge and Powell, 2008). Aphids also are attracted to olfactory cues such as volatile compounds that are emitted by virus-infected plants (Medina-Ort- ega et al., 2009). Thrips, Frankliniella occidentalis, demonstrate a higher frequency of feeding behavior upon infection by Tomato spotted wilt virus (TSWV) (Stafford et al., 2011). In addition to plant viruses, animal viruses also can have positive effects on vector insects. Mosquitoes infected with viruses show higher rates of bit- ing (Grimstad et al., 1980; Turell et al., 1985). This type of positive modification can be explained through the facilitation of virus transmission (Hurd, 2003; Lefèvre and Thomas, 2008). However, in some cases, vectors undergo negative or neutral modifications upon virus transmission. Specifically, longevity and fecundity of vectors either decrease or remain unchanged upon virus infection (Rubinstein and Czosnek, 1997; Matsuura and Hoshino, 2009). Froissart et al. (2010) reviewed the complex interactions among viruses, vectors, and plants in the context of the virulence- transmission trade-off hypothesis for vector-borne plant viruses. However, until now, the precise mechanisms facilitating the mod- ifications vectors undergo upon virus infection remain unanswered at the physiological and molecular levels. Sweet potato whitefly, Bemisia tabaci, is a vector of more than 100 plant-diseased viruses as well as a serious pest of various hor- ticultural crops (Henneberry et al., 2002; Navas-Castillo et al., 2011). This organism mediates its damage both directly, by feeding on the phloem, or indirectly by transmitting a wide array of viruses, most notably Tomato yellow leaf curl virus (TYLCV) (Czosnek et al., 2002). Until now, the results of previous studies on the acquisition and transmission of TYLCV by B. tabaci are controversial (Rubinstein 0022-1910/$ - see front matter Ó 2012 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.jinsphys.2012.07.008 ⇑ Corresponding author. Tel.: +82 53 950 5759; fax: +82 53 950 6758. E-mail address: leeky@knu.ac.kr (K.-Y. Lee). Journal of Insect Physiology xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Journal of Insect Physiology journal homepage: www.elsevier.com/locate/jinsphys Please cite this article in press as: Pusag, J.C.A., et al. Upregulation of temperature susceptibility in Bemisia tabaci upon acquisition of Tomato yellow leaf curl virus (TYLCV). Journal of Insect Physiology (2012), http://dx.doi.org/10.1016/j.jinsphys.2012.07.008