Park Ikju, Smith Lincoln
Invasive Species and Pollinator Health Research Unit, USDA ARS Western Regional Research Center, 800 Buchanan St., Albany, CA 94706, USA.
Department of Entomology and Nematology, University of California Davis, Davis, CA 95616, USA.
Insects. 2021 Sep 16;12(9):834. doi: 10.3390/insects12090834.
Classical biological control is an important method for controlling invasive alien weeds. Univoltine insects can be highly effective biological control agents of annual weeds because they are well synchronized with their host plant. However, having only one generation per year makes it difficult and slow to multiply them in the laboratory for initial field releases. If it were possible to terminate reproductive diapause early, then we could rear multiple generations per year, which would greatly increase annual production. We used a recently approved biocontrol agent, (a univoltine weevil), for yellow starthistle () as a model system to study the use of two insect hormones, 20-hydroxyecdysone (20E) and methoprene, to terminate reproductive diapause. Methoprene (1 μg applied topically) terminated reproductive diapause of female weevils, whereas doses of 0.0, 0.01 and 0.1 μg did not. The combination of methoprene and 20E had a stronger effect and induced an increase in eggs (1.51 ± 0.16 eggs/day, mean ± SE) compared with a methoprene only group (1.00 ± 0.13 eggs/day), and a control group (0.21 ± 0.04 eggs/day). Thus, topical application of these hormones should enable us to rear the weevil out of its normal season and produce more than one generation per year, which will increase productivity of mass-rearing it for field release. Once released in the field, the insect would continue as a univoltine agent that is well-synchronized with its host plant.
经典生物防治是控制外来入侵杂草的重要方法。单化性昆虫可以成为一年生杂草的高效生物防治剂，因为它们与寄主植物的物候期高度同步。然而，每年只繁殖一代使得在实验室中繁殖它们以供初次田间释放既困难又缓慢。如果能够提前终止生殖滞育，那么我们就可以每年饲养多代，这将大大提高年产量。我们使用一种最近获批用于防治黄矢车菊的生物防治剂（一种单化性象鼻虫）作为模型系统，来研究使用两种昆虫激素，即20-羟基蜕皮酮（20E）和烯虫酯，来终止生殖滞育。烯虫酯（局部施用1微克）可终止雌性象鼻虫的生殖滞育，而0.0、0.01和0.1微克的剂量则不能。与仅使用烯虫酯的组（1.00±0.13枚卵/天）和对照组（0.21±0.04枚卵/天）相比，烯虫酯和20E的组合效果更强，可使产卵量增加（1.51±0.16枚卵/天，平均值±标准误）。因此，局部施用这些激素应能使我们在正常季节之外饲养象鼻虫，并每年繁殖多代，这将提高大量饲养以供田间释放的生产率。一旦释放到田间，这种昆虫将继续作为与寄主植物物候期高度同步的单化性防治剂。
