兩種番茄豆類金黃嵌紋病毒對於菸草粉蝨生活史及行為之影響

Abstract

番茄黃化捲葉病 (tomato yellow leaf curl disease) 是由一群親源相近的番茄黃化捲葉病毒 (tomato yellow leaf curl viruses) 所引起的，嚴重危害全世界番茄產業。番茄黃化捲葉病毒屬雙生病毒科 (Geminiviridae)、豆類金黃嵌紋病毒屬 (Begomovirus)。許多研究顯示番茄黃化捲葉病毒對於其媒介昆蟲-菸草粉蝨 (Bemisia tabaci) 具有負面或中性的直接效應。番茄黃化捲葉病毒對於菸草粉蝨的間接效應被廣泛地研究，結果從負面、中性及正面的間接效應都有被報導。此外當菸草粉蝨獲得番茄黃化捲葉病毒後，會改變其取食偏好及行為。Tomato yellow leaf curl Thailand virus (TYLCTHV) 及 Tomato leaf curl Taiwan virus (ToLCTWV) 為國內番茄田間最主要流行的病毒。本研究探討 TYLCTHV 及 ToLCTWV 對於菸草粉蝨的生活史特徵和取食及產卵偏好之影響。結果顯示沒有感染與感染病毒 (TYLCTHV 或 ToLCTWV) 的粉蝨成蟲壽命及生殖力沒有顯著性的差異。當粉蝨於健康和 TYLCTHV 及 ToLCTWV 罹病植株上取食，除了粉蝨在感染 ToLCTWV 植株上的生殖力顯著性低於在健康植株上外，兩種病毒對粉蝨的壽命及生殖力也沒有顯著的間接效應。這些結果顯示相較 TYLCTHV，ToLCTWV 會間接地降低菸草粉蝨的生殖力。菸草粉蝨若蟲在健康和 TYLCTHV 及 ToLCTWV 罹病植株上取食，除了若蟲在感染 ToLCTWV 植株上的發育時間顯著長於在健康植株上外，兩種病毒對若蟲的存活率及發育時間沒有顯著的間接效應。此外，沒有感染病毒及感染 TYLCTHV 粉蝨成蟲偏好駐足健康植株；然而感染 ToLCTWV 粉蝨成蟲在罹病及健康植株之間沒有表現出寄主選擇偏好性。這些結果顯示 ToLCTWV 會改變菸草粉蝨成蟲寄主選擇偏好。產卵偏好實驗結果顯示沒有感染植物病毒和感染植物病毒 (TYLCTHV 或 ToLCTWV) 粉蝨雌蟲，在健康或罹病植株的產卵量皆沒有顯著性的差異；除了沒有感染植物病毒的粉蝨在健康和 ToLCTWV 罹病植株之間偏好在 ToLCTWV 罹病植株上產卵。豆類金黃嵌紋病毒屬病毒對於菸草粉蝨的生活史及行為之影響，可能會因為病毒種類不同而有不同的結果。

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.