Department of Parasitology, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
Parasit Vectors. 2020 May 6;13(1):228. doi: 10.1186/s13071-020-04109-y.
Insect growth regulators (IGRs) are considered a novel group of insecticides to control mosquitoes. Novaluron is an IGR with benzoylphenyl urea insecticide, which inhibits chitin synthesis in insects and can reduce insect population density; it is also known to have a high margin of safety for mammals.
The effective minimum concentration of novaluron formulation EC10 was tested. Six pineapple plantations [control (n = 3) and test (n = 3)] were selected from Meerigama Medical Officer of Health area in Gampaha District, Sri Lanka. Fifteen plots (10 × 10 m) were demarcated in each site with a 200 m distance apart. Leaf axils of 450 pineapple plants (30 plants × 15 plots) were screened for immature stages of Aedes mosquitoes weekly for 12 weeks. The required concentration (20 ppm) of novaluron was sprayed onto the selected pineapple plants (n = 1350) individually in 3 selected test sites for 5-10 s. The reduction in the vector population was interpreted as the percentage of reduction in immature stages of Aedes mosquitoes.
The 100% mortality of the Ae. aegypti larvae within 24 h was observed at 20 ppm (0.05 ml of novaluron 100 g/l in 250 ml of water) as the minimum dose. Variation in the number of Aedes larvae present in the control and intervention sites was found to be significantly different throughout the entire observational period (χ = 128.29, df = 11, P < 0.001). The total elimination of Aedes larvae continued for up to 2 weeks and a 50% reduction was observed until the 8th week.
The present study emphasizes that novaluron (10% EC) can be used as an effective larvicide at the treatment dose of 20 ppm. The residual effect of the IGR lasted for 12 weeks with a functional efficacy of 8 weeks. The 100% reduction of larval breeding was observed up to the 2nd week after application and the percentage reduction of immature stages remained > 50% until the 8th week. The lowest reduction (34.2%) was observed at 12 weeks after the initial treatment. Therefore, re-treatment may be recommended based on the reduction in the efficacy of the IGR.
昆虫生长调节剂（IGR）被认为是一类新型杀虫剂，可用于控制蚊子。双氧威是一种苯甲酰基苯脲类杀虫剂，它可以抑制昆虫的几丁质合成，从而降低昆虫种群密度; 同时，它对哺乳动物的安全性也很高。
测试了双氧威制剂 EC10 的有效最低浓度。在斯里兰卡 Gampaha 区 Meerigama 医疗官辖区内选择了 6 个菠萝种植园（对照组 n=3，实验组 n=3）。在每个地点划出 15 个地块（10×10 m），每个地块之间的距离为 200 m。每周对 450 株菠萝植株（30 株×15 个地块）的叶腋进行检查，以筛查伊蚊的未成熟阶段，共持续 12 周。将所需浓度（20 ppm）的双氧威单独喷洒在 3 个选定的试验区的 300 株菠萝植株上（n=1350），每个试验区喷洒 5-10 秒。通过计算未成熟伊蚊数量的减少百分比来评估媒介种群的减少情况。
在 24 小时内，观察到 20 ppm（双氧威 100 g/l，0.05 ml 于 250 ml 水中）剂量下，埃及伊蚊幼虫的死亡率达到 100%。在整个观察期间，发现对照组和干预组的伊蚊幼虫数量存在显著差异（χ=128.29，df=11，P<0.001）。伊蚊幼虫的完全消灭持续了 2 周，在第 8 周观察到减少了 50%。
本研究强调，双氧威（10% EC）可作为一种有效的杀虫剂，在 20 ppm 的治疗剂量下使用。IGR 的残留效果持续了 12 周，功能效果持续了 8 周。在施药后第 2 周，观察到幼虫繁殖减少了 100%，直到第 8 周，未成熟阶段的减少率仍保持在 50%以上。在初始处理后 12 周，观察到的减少率最低（34.2%）。因此，根据 IGR 效果的降低，可能需要再次进行处理。
