斜紋夜蛾核多角體病毒台灣分離株之致病力與體內增殖之研究

Pathogenicity and propagation of Spodoptera litura nuclear polyhedrosis virus isolated in Taiwan

段淑人(Tuan, S. J.) ； 高穗生(Kao, S. S.) ； 劉員良(Leu, U. L.) ； 鄭朵智(Cheng, D. J.)

《中華昆蟲》 15卷1期 (1995/03) Pp. iii+19-33

https://doi.org/10.6660/TESFE.1995003

摘要

自本地之斜紋夜蛾（Spodoptera litura（Fab.））罹病幼蟲體內分離之核多角體病毒，經電子顯微鏡觀察其外形為多角體，平均直徑大小約為1.90μm。每個多角體所含之病毒粒子數量一般約數十個，而每個病毒粒子內又含有數個長桿狀之核蛋白鞘。病毒感染寄主之細胞核，在其內複製增殖使細胞核腫脹破裂，故名為斜紋夜蛾核多角體病毒（Spodoptera litura multiple nuclear polyhedrosis virus, SIMNPV）。此病毒對斜紋夜蛾幼蟲具頗高之致病力，以接種源飲入法測得1至6齡幼蟲之半致死濃度（LC_(50)）依序為5.47x10^5、4.47x10^4、6.16x10^5、3.12x10^6、1.43x10^7、以及7.28x10^8 PIBs/ml。隨供試齡期之增加，幼蟲對病毒的感受性有下降之趨勢，且其半致死時間亦隨之加長。病毒在寄主幼蟲體內增殖量與幼蟲體重及接種濃度間有正相關。5齡幼蟲之病毒產量遠高於4齡者。在30℃下，接種後2至3天幼蟲體內病毒含量急遽上升，至5天達到最高峰。若於35℃下，雖可提前達到高峰，但因高溫加速幼蟲之死亡，而使罹病幼蟲之體重及病毒之最終產量不如在30℃下為高。每隻幼蟲以接種源飲入法飼餵10^5 PIBs，之後置於30℃生長箱中，至第5天即收取全部病蟲，平均每隻病蟲可回收病毒2.47x10^9 PIBs，為接種劑量之25,000倍。病毒液經冷凍乾燥後每克粉末含有3.07x10^(10) PIBs。

關鍵字

斜紋夜蛾 ； 核多角體病毒 ； 致病力 ； 半致死濃度 ； 半致死劑量

並列摘要

A nuclear polyhedrosis virus (S1MNPV) was isolated from a single larva of the tobacco cutworm, Sopdoptera litura (Fab.), in Wufeng, Taiwan. Electron micrographs showed that the polyhedra were irregularly measuring ca. 1.90μm in diameter, and that the virion contained several nucleocapsids within the envelope. The virion is rod-shaped, with parallel sides and round ends. The nucleocapsid is enlongated with parallel sides and straight ends, measuring 324 x 48 nm. This S1MNPV isolate was highly pathogenic to S. litura larvae, with LC_(50) values being 5.47x10^5, 4.47x10^4, 6.16x10^5, 3.12x10^6, 1.4x10^7, and 7.28x10^8 PIBs/ml for the 1st to 6th instar, respectively, as assayed by inoculum-imbibing method. The LT_(50) values of inoculated larvae were also delayed as the larvae were getting older. Thus S. litura larvae became less susceptible to S1MNPV with age. Polyhedra of S1MNPV were propagated in 4th- and 5th-instar larvae by the inoculum-imbibing method. The viral yield was compared, by producing at various inoculum dosages, incubated at 30 and 35℃.The number of polyhedra produced was positively correlated with larval weight and inoculum dosage. Higher incubation temperature resulted in higher larval mortality. The larvae were killed before reaching maximum body weight, resulting in lower yields of the virus when incubated at higher temperatures. The polyhedra could be detected one day to post-inoculation (pi), and increased rapidly on day 2-3 (pi), reaching the highest level production on day 5. The maximum number of polyhedra was 2.47x10^9 PIBs per larva, and 3.07x10^(10) PIBs per gram after lyophilization.

並列關鍵字

Spldotera litura ； nuclear polyhedrosis virus ； S1MNPV LC_(50) ； LD_(50) ； LT_(50)