Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Pest Manag Sci. 2022 Feb;78(2):812-820. doi: 10.1002/ps.6696. Epub 2021 Nov 9.
Seedling transplanting is widely used in rice cultivation. Systemic insecticides can be delivered to seedling roots by application through rice seedling boxes before transplanting. The most challenging aspect is to provide long-term control of rice pests and overcome transplanting shock. Precise control of the release rate of insecticide can meet these requirements. Pymetrozine is a promising insecticide used for the control of rice planthoppers resistant to neonicotinoid insecticides.
In this study, four controlled-release granular formulations of pymetrozine were prepared based on a mixture of cost-effective and biodegradable kaolin and xanthan gum or a mixture of calcined kaolin and xanthan gum. Fluorescence images showed that different 3D networks were formed in the four granular formulations. The four granular formulations showed different water uptake rates and release rates of pymetrozine in water. Pymetrozine release rate was positively correlated with the water uptake capacity, rather than the water uptake rate of granules. Diffusion was the dominant mechanism for the release of pymetrozine from granules. Pymetrozine was found to reduce the survival of transplanted rice seedlings suffering from transplanting shock. Incorporating pymetrozine in controlled-release granules alleviated this phytotoxicity. The survival rate of rice seedlings in granular pymetrozine treatments ranged 68.8-85.0%, whereas the survival rate was <50% for powdered pymetrozine treatments. Additionally, four prepared granule formulations had a significant control effect on rice planthopper with efficacies ranging from 76.7% to 98.0% 40 days after seedling box treatment.
The granule with an intermediate release rate of pymetrozine was shown to be more suitable for seedling box treatment than field application and traditional liquid spraying for the long-term control of paddy planthoppers. © 2021 Society of Chemical Industry.
水稻移栽中广泛采用育秧盘播种技术。在移栽前，可将系统杀虫剂通过育秧盘施用于稻苗根部，从而送达稻苗根部。最具挑战性的方面是提供对水稻害虫的长期控制并克服移栽冲击。精确控制杀虫剂的释放速率可以满足这些要求。吡丙醚是一种有前途的杀虫剂，用于防治对新烟碱类杀虫剂具有抗性的稻飞虱。
本研究以廉价且可生物降解的高岭土和黄原胶或煅烧高岭土和黄原胶的混合物为基础，制备了 4 种吡丙醚控释粒剂。荧光图像显示，在这 4 种粒剂中形成了不同的 3D 网络。这 4 种粒剂在水中表现出不同的吸水速率和吡丙醚释放速率。吡丙醚的释放速率与颗粒的吸水能力呈正相关，而与颗粒的吸水速率无关。扩散是吡丙醚从颗粒中释放的主要机制。发现吡丙醚降低了移栽冲击下移栽水稻幼苗的存活率。将吡丙醚包埋在控释颗粒中可减轻这种植物毒性。在颗粒吡丙醚处理中，水稻幼苗的存活率范围为 68.8-85.0%，而在粉状吡丙醚处理中，存活率<50%。此外，4 种制备的粒剂配方对稻飞虱具有显著的防治效果，药后 40 天防治效果在 76.7%至 98.0%之间。
与田间应用和传统的液体喷雾相比，具有中等释放速率的吡丙醚粒剂更适合育秧盘处理，可用于长期防治稻田中的稻飞虱。© 2021 英国化学学会。
