Glover James Paul, Spaulding Nathan, George Justin, Portilla Maribel, Reddy Gadi V P, Dillman Adler
USDA-ARS, Southern Insect Management Research Unit, Stoneville, MS 38776, USA.
Department of Nematology, UC Riverside, CA 92521, USA.
J Nematol. 2025 Apr 24;57(1):20250012. doi: 10.2478/jofnem-2025-0012. eCollection 2025 Feb.
is a major agricultural pest, particularly in cotton, and poses significant challenges due to its ability to develop resistance to chemical insecticides. This study evaluates the efficacy of the entomopathogenic nematode () and its mutualistic bacteria () as biological control agents against larvae in both laboratory and field settings. In laboratory assays, mortality rates for 1 to 4 instars were high, ranging from 74.2% to 100%, while 5 instars exhibited significantly lower susceptibility (<37% mortality). Pupae were completely resistant to nematode infection. The impact of UV radiation on nematode efficacy was assessed, with mortality decreasing from 100% in control conditions (0 hours of UV exposure) to 71.8% after 5 hours of UV exposure, highlighting the vulnerability of to UV degradation. In addition, caused 100% mortality in larvae when injected directly into the hemocoel, but oral toxicity was significantly lower, with 36% mortality in 7 days post-exposure. Field experiments demonstrated that the combination of with 0.05% sodium alginate (hygroscopic agent) and 0.02% Congo red (UV protectant) resulted in a significant increase in larval mortality. In field test A, where was applied in water, mortality averaged 56% with 82% EPN infection. In field test B, the combined treatment of sodium alginate and Congo red led to 98% larval mortality, although infection rates were lower and statistically non-significant. The addition of these protective agents likely enhanced the environmental stability and efficacy of the nematodes under field conditions. These findings suggest that can be an effective biological control agent for , particularly when combined with formulations that protect against UV radiation and desiccation. Future research should focus on optimizing nematode delivery systems to improve field efficacy under diverse environmental conditions.
是一种主要的农业害虫，尤其在棉花种植中危害严重，因其对化学杀虫剂产生抗性的能力而带来了重大挑战。本研究评估了昆虫病原线虫（）及其共生细菌（）作为生物防治剂在实验室和田间环境中对幼虫的防治效果。在实验室测定中，1至4龄幼虫的死亡率很高，在74.2%至100%之间，而5龄幼虫的易感性显著较低（死亡率<37%）。蛹对线虫感染完全具有抗性。评估了紫外线辐射对线虫防治效果的影响，死亡率从对照条件下（0小时紫外线暴露）的100%下降到5小时紫外线暴露后的71.8%，突出了对紫外线降解的脆弱性。此外，直接注入血腔时可导致幼虫100%死亡，但口服毒性显著较低，暴露7天后死亡率为36%。田间试验表明，与0.05%海藻酸钠（吸湿剂）和0.02%刚果红（紫外线保护剂）组合使用可显著提高幼虫死亡率。在田间试验A中，在水中施用时，平均死亡率为56%，线虫感染率为82%。在田间试验B中，海藻酸钠和刚果红的联合处理导致幼虫死亡率达到98%，尽管感染率较低且无统计学显著性。添加这些保护剂可能增强了线虫在田间条件下的环境稳定性和防治效果。这些发现表明，可成为防治的有效生物防治剂，特别是与防止紫外线辐射和干燥的制剂联合使用时。未来的研究应侧重于优化线虫投放系统，以提高在不同环境条件下的田间防治效果。
