Departamento de Fitotecnia e Zootecnia, Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista, Bahia, 45031-900, Brazil.
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, Brazil.
Pest Manag Sci. 2022 Jun;78(6):2581-2587. doi: 10.1002/ps.6889. Epub 2022 Apr 16.
Coffee (Coffea arabica L.) is one of the main commodities produced in Brazil. Insecticides like the (systemic) neonicotinoid thiamethoxam are widely used to suppress pest populations during coffee production, in particular the Neotropical leaf miner (Leucoptera coffeella Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae). In addition to its efficacy against this pest species, thiamethoxam is also thought to be a bioactivator of plant metabolism, but has not yet been tested for such activity. Thus, the objectives of the present study were (1) to assess the concentration-response effects of thiamethoxam on the vegetative vigor of coffee seedlings (C. arabica 'Catuaí 144' cultivar) at different concentrations [2, 20, 40, 80 and 200 mg active ingredient (a.i.) kg ] applied via soil drenching and (2) to evaluate if the plant response interferes with the effectiveness of thiamethoxam in controlling leaf miner populations. The morphophysiological traits of the coffee seedlings were evaluated 20, 40, 60 and 80 days after application, and leaf miner infestations were recorded starting 20 days after the insecticide application with the releasing of adults, and every 20 days afterwards.
The results indicated that thiamethoxam has a deleterious effect on the morphophysiological traits of the plants compromising their development with increase in concentrations. However, leaf area exhibited a different pattern with a peak at 50 mg a.i. kg consistent with thiamethoxam-induced hormesis (i.e. biphasic response with stimulatory effect at sublethal range of a toxic substance at the higher concentration). Nonetheless, such bioactivator effect did not affect thiamethoxan effectiveness against the leaf miner even at the lowest concentration tested.
Thiamethoxan exhibited bioactivation effect on leaf at low concentration, but without compromising efficacy against leaf miner populations. Therefore, its proposed metabolism-boosting properties may encourage the unnecessary use of this insecticide, potentially leading to higher selection for insecticide resistance and an eventual decline in its effectiveness against the Neotropical leaf miner. © 2022 Society of Chemical Industry.
咖啡（Coffea arabica L.）是巴西主要的商品之一。杀虫剂，如（系统性）新烟碱类噻虫嗪，广泛用于抑制咖啡生产过程中的害虫种群，特别是新热带叶潜蝇（Leucoptera coffeella Guérin-Mèneville & Perrottet, 1842）（鳞翅目：潜蝇科）。除了对这种害虫物种有效外，噻虫嗪还被认为是植物代谢的生物激活剂，但尚未对此类活性进行测试。因此，本研究的目的是（1）评估噻虫嗪通过土壤淋溶以不同浓度[2、20、40、80 和 200 毫克有效成分（a.i.）kg]处理对咖啡幼苗（C. arabica 'Catuaí 144' 品种）的生长活力的浓度-反应效应，（2）评估植物的反应是否会干扰噻虫嗪控制叶潜蝇种群的效果。在施用后 20、40、60 和 80 天评估咖啡幼苗的形态生理特征，并在释放成虫后开始记录叶潜蝇的侵染，之后每 20 天记录一次。
结果表明，噻虫嗪对植物的形态生理特性具有有害影响，随着浓度的增加，会损害其发育。然而，叶片面积表现出不同的模式，在 50 毫克 a.i.kg 时达到峰值，与噻虫嗪诱导的激素作用一致（即在有毒物质的亚致死范围内，刺激作用的双相反应在较高浓度下）。尽管如此，即使在测试的最低浓度下，这种生物激活作用也不会影响噻虫嗪对叶潜蝇的效果。
噻虫嗪在低浓度下对叶片表现出生物激活作用，但不会影响其对叶潜蝇种群的效果。因此，其提议的促进代谢特性可能会鼓励不必要地使用这种杀虫剂，从而可能导致对杀虫剂的更高选择压力，最终降低其对新热带叶潜蝇的效果。© 2022 英国化学学会。
