| Summary: | 碩士 === 國立臺灣大學 === 昆蟲學研究所 === 103 === Tomato yellow leaf curl disease caused by a group of closely-related tomato yellow leaf curl viruses (TYLCVs) is a major threat to tomato industry worldwide. TYLCVs belong to the genus Begomovirus in the family Geminiviridae. Many studies showed TYLCVs have negative or neutral direct effects on the life history of their insect vector, Bemisia tabaci. The indirect effects of TYLCVs on B. tabaci have been well studied, and the results vary from negative, to neutral, and to positive. In addition, TYLCVs alter the feeding preference and behavior of B. tabaci when they carry the viruses. Tomato yellow leaf curl Thailand virus (TYLCTHV) and Tomato leaf curl Taiwan virus (ToLCTWV) are two predominant viruses in tomato fields in Taiwan. In this study, the direct and indirect effects of TYLCTHV and ToLCTWV on the life history traits, host preference, and oviposition preference of B. tabaci were examined. No significant variations were observed between the nonviruliferous and TYLCTHV/ToLCTWV-infected adult whiteflies regarding longevity and fecundity. The longevity and fecundity of adult whiteflies did not differ significantly between those fed on the healthy and TYLCTHV/ToLCTWV-infected plants, except that whiteflies laid more eggs when they fed on the healthy plants than on the ToLCTWV-infected plants. The developmental time and survival rate did not differ significantly between whitefly nymphs fed on the healthy and those fed on the TYLCTHV/ToLCTWV-infected plants, except that whitefly nymphs needed longer developmental time when they fed on the ToLCTWV-infected plants than on the healthy plants. These results implied that ToLCTWV, but not TYLCTHV, indirectly decreased the fecundity of B. tabaci. In addition, nonviruliferous and TYLCTHV-infected whiteflies preferred to settle on the healthy plants. However, ToLCTWV-infected whiteflies did not exhibit a preference between the healthy and ToLCTWV-infected tomato plants. These results implied that ToLCTWV, but not TYLCTHV, altered the host preference of B. tabaci. Oviposition preference experiment showed the egg numbers of nonviruliferous and viruliferous (TYLCTHV or ToLCTWV) female whiteflies on the TYLCTHV/ToLCTWV-infected plants did not differ from those on the healthy plants, except that nonviruliferous female whiteflies prefer to lay more eggs on ToLCTWV-infected plant than healthy plant. The effects of begomoviruses on the life history and feeding preference of B. tabaci might vary among virus species.
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