Effect Of Host Plant And Temper Ature And Virus On Bemisia Tabaci Biotype B And Q

The sweet potato whitefly, Bemisia tabaci (Gennadius)(Hemiptera:Aleyrodidae), has been regarded as the one of the most destructive worldwide pest insects which can endanger the economic crop such as the vegetables, flowers, and cotton. The effects of temperature and host plant on phenotypic plasticity and biochemical characteristics of B. tabaci B and Q biotypes were compared. Tomato yellow leaf curl virus (TYLCV) was transmitted by B. tabaci in a circulative manner and are persistent in the whitefly vector. In addition, the effect of TYLCV on the egg size of B. tabaci biotypes B and Q was also compared. In order to compared the effect of the long-time isolation rearing populations in different host plants include toamto, cucumber, and cabbage on the ability of acquisition and transmission of TYLCV by B. tabaci, the relative concentration of TYLCV was quantified viaquantitative PCR method. It has recently been demonstrated that a63-kDa GroEL homologue produced by the endosymbiotic bacteria Hamiltonella is essential for the circulative transmission of the virus in B. tabaci. The relative concentration of Hamiltonella and GroEL in B. tabaci that feeding on TYLCV-infected plants for0h,12h, and24h between females and males were compared.(1) Long-term rearing on alternative host-plant species over multiple generations may shape herbivorous insects’ preference and performance. In the present study, the effects of long-term rearing experience on host preference and performance of Bemisia tabaci B biotypewere explored. Three populations reared on poinsettia, cotton, and cabbage with the similar genetic background were established in2004, respectively. After about60generations, the feeding and oviposition preference, and adult (longevity and fecundity) and nymph performance (development and survival) of each population on three host species were investigated. B. tabaci females preferred feeding and nymph performed better on their reared host species over on alternative host species. However, most females preferred ovipositing on cabbage independent of their prior experience. Our results demonstrated that the rearing experience of B. tabaci females positively shaped their feeding preference and performance.(2) Temperature and host species are two particularly important and widespread mediators of phenotypic variation in phytophagous insects, resulting in predictable plastic changes in egg and body size. However, the adaptive significance of egg size plasticity in response to temperature and host plant have not been investigated in most study systems. In the present studythe egg size plasticity in response to temperatures (20℃and27℃) and host plants (cucumber and cotton) in B biotype B. tabaci were determined. Our results showed that egg width was positively related with egg length, regardless of rearing temperature and host species. When B. tabaci females exposed on different host plants and under different temperatures for1week, egg sizes differed greatly under different conditions, accordingly. The egg widths of females reared on cucumber and under27℃were significantly greater than those reared on cotton and under20℃, respectively. However, no significant difference was exsit in egg width of females acclimatized under different conditions for2weeks. When B. tabaci females exposed on different host plants and under different temperatures for2weeks, egg length of females exposed under20℃were significantly greater than those under27℃, regardless of host species.(3) In order to shed some new light on the competitive displacement between B. tabaci B and Q biotypes, the differences of courtship and mating behaviours between the two biotypes in response to different temperatures wre investigated. Our results indicated that the sexual behaviours of these two biotypes were significantly influenced by temperature. With the increase of temperature, male courtship latency decreased successively, while mating frequency increased. However, there were no significant difference in courtship and mating behaviours between B and Q biotypes under the same temperature. It seems unlikely that the effects of temperature on sexual behaviours played an important role on the competitive displacement between B. tabaci B and Q biotypes.(4) Three detoxifying enzymes including carboxylesterase, glutathione-S-transferase, and mixed-function oxidase play important role of insects in decomposing exogenous toxins, maintaining normal physiological metabolism. By analyzing the differences of the three detoxifying enzymes of the B. tabaci B and Q biotypes on cabbageand pepper, respectively, the enzyme inhibitors were also used to verify the function of detoxification enzymes.The results indicated that different enzyme made a different role in resistance to plant secondary metabolites, carboxylesterase involved in resistance to cabbage secondary metabolites, mixed-function oxidase involved in resistance to pepper secondary metabolites.(5) The infection of TYLCV has impact on the biological characteristics of Bemisia tabaci. In the current study, the differences in the female body length, the length, and width of eggs ovipositied by viruliferous and non-viruliferous B. tabaci B and Q biotypes were compared. The results indicated that no significant difference in female body length between viruliferous B and Q biotypes and non-viruliferous B and Q biotypes, respectively. The length and width of eggs oviposited by viruliferous B biotype were significantly larger than that oviposited by non-viruliferous B biotype, respectively. However, the length and width of eggs oviposited by viruliferous Q biotype were significantly smaller than that oviposited by non-viruliferous Q biotype, respectively. Overall, the egg size of B and Q biotypes responded differently to TYLCV, whereas no impact for the female body length.(6) In order to explore the impactof long-term rearing and sex on the ability of acquisition and transmission TYLCV by B. tabaci, the females and males of the three populations including tomato, cucumber, and cabbage, were used to investigated the ability of acquisition and transmission TYLCV. The relative concentration of Hamiltonella and GroEL in B. tabaci that feeding on TYLCV-infected plants for Oh,12h, and24h between females and males of the cabbage population were compared. on.The results showed that no significant differences exsit between the acquisition and transmission of TYLCV among the three populations, no significant differences of the ability of acquisition between females and males within the same population, however, no the transmission ability of females were significantly higher than of males,.The relative concentration of Hamiltonella and the relative expression of GroEL were higher in females than in males, and increased greatly in viruliferous than in non-viruliferous whiteflies.