Treacy M F, Rensner P E, All J N
American Cyanamid Company, Agricultural Research Center, Princeton, NJ 08543-0400, USA.
J Econ Entomol. 2000 Aug;93(4):1096-104. doi: 10.1603/0022-0493-93.4.1096.
Laboratory, greenhouse and field studies were conducted to characterize the insecticidal properties of genetically altered forms of Autographa californica (Speyer) nucleopolyhedrovirus (AcNPV) and Helicoverpa zea (Boddie) NPV (HzNPV) against selected heliothine species. The altered viruses each contained a chimeric 0.8-kb fragment encoding the insect-specific, sodium channel neurotoxin from the Algerian scorpion Androctonus australis Hector (AaIT, hence recombinant viruses designated Ac-AaIT and Hz-AaIT). Based on LD50 values, results from diet-overlay bioassays showed Ac-AaIT and Hz-AaIT to be equally virulent against larval tobacco budworm, Heliothis virescens (F.), but Hz-AaIT averaged 1,335-fold greater bioactivity than Ac-AaIT against larval cotton bollworm, Helicoverpa zea (Boddie). Hz-AaIT killed larvae of both heliothine species at rates significantly faster than those imparted by HzNPV (viral LT50 values averaged 2.5 and 5.6 d, respectively). In greenhouse studies, foliar sprays of Ac-AaIT and Hz-AaIT were equally effective in controlling H. virescens on cotton; however, Hz-AaIT provided control of H. zea on cotton at a level superior to that of Ac-AaIT. For example, after three weekly sessions of foliar application and H. zea artificial infestation, cotton treated with Ac-AaIT or Hz-AaIT at 10 x 10(11) occulsion bodies (OB)/ha averaged 2.5 and 16.2 nondamaged flower buds per plant, respectively. Another greenhouse study conducted against heliothine species on cotton showed that the quicker killing speed exhibited by Hz-AaIT led to improved plant protection versus HzNPV. Finally, results from three field trials demonstrated that Hz-AaIT at 5-12 x 10(11) OB/ha provided control of the heliothine complex in cotton at levels slightly better than Bacillus thuringiensis, equal to the macrolide, spinosad, and only slightly less than that of selected pyrethroid and carbamate insecticides. Overall, results from these studies indicate that, because of host range differences between the two wild-type viruses, HzNPV is the better vectoring agent (versus AcNPV) for designing recombinant clones as insecticides targeted at the multi-species heliothine complex. Further, these studies suggest that if appropriately tailored for the pest complex, recombinant NPVs may be very effective, insect-specific approaches to managing pests in many cropping scenarios. Possible Hz-AaIT deployment strategies for control of heliothine species on conventional and transgenic cotton varieties are discussed.
开展了实验室、温室和田间研究，以表征经基因改造的苜蓿银纹夜蛾（Autographa californica (Speyer)）核多角体病毒（AcNPV）和棉铃虫（Helicoverpa zea (Boddie)）NPV（HzNPV）对选定的夜蛾科物种的杀虫特性。改造后的病毒均包含一个0.8 kb的嵌合片段，该片段编码来自阿尔及利亚蝎子黄肥尾蝎（Androctonus australis Hector）的昆虫特异性钠通道神经毒素（AaIT，因此重组病毒命名为Ac - AaIT和Hz - AaIT）。基于半数致死剂量（LD50）值，饲料涂抹生物测定结果表明，Ac - AaIT和Hz - AaIT对烟草天蛾幼虫（Heliothis virescens (F.)）的毒性相同，但Hz - AaIT对棉铃虫幼虫（Helicoverpa zea (Boddie)）的生物活性平均比Ac - AaIT高1335倍。Hz - AaIT杀死两种夜蛾科物种幼虫的速度明显快于HzNPV（病毒半数致死时间（LT50）值平均分别为2.5天和5.6天）。在温室研究中，Ac - AaIT和Hz - AaIT的叶面喷雾在控制棉花上的烟草天蛾方面效果相同；然而，Hz - AaIT对棉花上棉铃虫的防治效果优于Ac - AaIT。例如，在进行三次每周一次的叶面喷施并人工接种棉铃虫后，以10×10¹¹包涵体（OB）/公顷的剂量用Ac - AaIT或Hz - AaIT处理的棉花，平均每株分别有2.5个和16.2个未受损的花蕾。另一项针对棉花上夜蛾科物种的温室研究表明，Hz - AaIT表现出的更快杀灭速度使其对棉花的保护效果优于HzNPV。最后，三项田间试验结果表明，5 - 12×10¹¹ OB/公顷的Hz - AaIT对棉花上夜蛾科害虫复合体的防治效果略优于苏云金芽孢杆菌，与大环内酯类杀虫剂多杀菌素相当，仅略低于某些拟除虫菊酯类和氨基甲酸酯类杀虫剂。总体而言，这些研究结果表明，由于两种野生型病毒的宿主范围不同，HzNPV是（相对于AcNPV）更好的载体，可用于设计作为针对多种夜蛾科害虫复合体的杀虫剂的重组克隆。此外，这些研究表明，如果针对害虫复合体进行适当调整，重组NPV可能是在许多种植场景中管理害虫的非常有效的、昆虫特异性方法。讨论了在常规和转基因棉花品种上控制夜蛾科物种的Hz - AaIT可能的部署策略。
