西瓜銀斑病毒的感染對南黃薊馬取食行為的影響

Effect of Watermelon silver mottle virus infection on the feeding behavior of Thrips palmi

朱英迪(Ying-Di Chu)

指導教授 ： 蔡志偉

國立臺灣大學/生物資源暨農學院/昆蟲學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201800600

摘要

許多植物病毒仰賴媒介昆蟲來傳播，病毒可能藉由操控其媒介昆蟲的行為來提升病毒傳播的效率，即是所謂的病媒操控假說 (vector manipulation hypothesis)。番茄斑萎病毒屬 (Orthotospovirus) 病毒不僅依靠薊馬傳播到健康寄主植物，也會在薊馬體內感染與複製，甚至病毒的感染會影響薊馬的行為。西瓜銀斑病毒 (Watermelon silver mottle virus, WSMoV)為一種在甜瓜田間造成嚴重危害的番茄斑萎病毒屬病毒，雖然西瓜銀斑病毒的感染並未直接影響其媒介昆蟲南黃薊馬 (Thrips palmi) 生活史特徵 (發育時間、壽命與產卵量等) 的變化，但仍會間接地影響南黃薊馬，使其發育期增長。這個研究透過昆蟲刺探電位圖譜 (electrical penetration graph, EPG) 監測薊馬口針穿刺行為，探討西瓜銀斑病毒的感染對南黃薊馬取食行為的直接與間接影響。在直接效應中，比較感染病毒的薊馬與健康薊馬的口針穿刺行為後，發現病毒感染直接地影響薊馬雌蟲與雄蟲穿刺行為的次數。短取食穿刺 (short ingestion probes) 的次數在感染病毒的雌蟲與雄蟲中皆顯著高於健康的雌蟲與雄蟲。雖然病毒的感染並未直接對薊馬非取食穿刺 (non-ingestion probes) 與長取食穿刺 (long ingestion probes) 的次數有影響，但感染病毒的薊馬的所有的穿刺行為次數仍高於健康薊馬。此外，病毒感染未直接影響三種穿刺行為的每次平均時間，也沒有改變總取食時間 (total ingestion time)。間接效應則是比較健康薊馬在西瓜銀斑病毒罹病植株與健康植株上取食行為的差異。間接效應在雌蟲與雄蟲有不同的結果，雌蟲被發現在取食罹病植株時有行為的改變，但雄蟲的取食行為則並不受到植株的罹病與否影響。與取食健康植株時相比，薊馬雌蟲在取食罹病植株時有較少的非取食穿刺次數與短取食穿刺次數，此外薊馬雌蟲的短取食穿刺則是在取食感染病毒植株時有較長的平均時間。當薊馬雌蟲在罹病植株上取食時有較長的總取食時間，西瓜銀斑病毒的感染對南黃薊馬的直接效應可能有助於病毒的傳播；其間接效應則能誘導南黃薊馬停留在罹病植株上。我的研究結果提供了病媒操控假說新的證據，並更進一步地增進了對薊馬與番茄斑萎病毒屬病毒的交互作用的了解。

關鍵字

昆蟲刺探電位圖譜 ； 取食行為 ； 口針穿刺 ； 南黃薊馬 ； 番茄斑萎病毒屬

並列摘要

Majority of plant viruses are exclusively transmitted by insect vectors. Virus may manipulate the behavior of its vector in order to increase its transmission rate which is known as vector manipulation hypothesis. Orthotospovirus not only relies on thrips to be transmitted to healthy plants but also infects and replicates in its vectors. Watermelon silver mottle virus is a tospovirus causing a serious problem in melon fields. Despite WSMoV infection does not directly affect the performance (developmental time, longevity, fecundity, etc.) of its vector, Thrips palmi, the indirect effect of virus infection elongates the developmental time of T. palmi. In this study, the direct and indirect effects of WSMoV infection on the feeding behavior of T. palmi were evaluated, using electrical penetration graphs (EPG) to monitor the probing events of thrips. For the direct effect of virus infection on the feeding behavior of T. palmi, the probing of viruliferous and non-viruliferous thrips was compared, and significant direct effects of WSMoV infection were found on the probing frequency of both females and males. The number of short ingestion probes per hour of viruliferous thrips were higher than those of non-viruliferous thrips in females and males. There was no difference in the number of non-ingestion probes and long ingestion probes per hour between viruliferous and non-viruliferous thrips. However, the number of all probes per hour of viruliferous thrips was higher than that of non-viruliferous thrips. The average durations of non-ingestion, short ingestion, and long ingestion probes were not affected by virus infection, and neither was the total ingestion time. The indirect effect of virus infection was examined by comparing the feeding behavior of non-viruliferous thirps on WSMoV-infected and healthy plants. The indirect effect of WSMoV infection was different among sexes. Behavioral changes were found when female thrips fed on virus-infected plant, but the infection status of plants did not change the feeding behavior of male thrips. The numbers of non-ingestion probes and short ingestion probes were lower when the female thrips fed on virus-infected plants compared to feeding on healthy plants. The average duration of short ingestion probes was longer when the female thrips fed on virus-infected plants than feeding on healthy plants. The total ingestion time per hour was longer when female thrips fed on virus-infected plants than feeding on healthy plants. The direct effect of WSMoV infection on the feeding behavior of T. palmi may benefit the virus and increase virus transmission rate, and the indirect effect of WSMoV infection may induce the arrestment of T. palmi to virus-infected plants versus healthy plants. My results provide another evidence for vector manipulation hypothesis and an insight in tospovirus-thrips interaction.

並列關鍵字

electrical penetration graph ； feeding behavior ； probing ； Thrips palmi ； Orthotospovirus

參考文獻

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