PHYSIOLOGIC SELECTIVITY OF PESTICIDES USED ON COFFEE PLANTATIONS ON EGGS AND ADULTS OF CRYPTOLAEMUS MONTROUZIERI MULSANT

ABSTRACT On coffee plantations, the association between selective compounds and natural enemies composes an important tool for the pest management. The objective of this study was to evaluate some pesticides used on coffee plantations in regard to their lethal and sublethal effects on eggs and adults of Cryptolaemus montrouzieri Mulsant under laboratory conditions. The bioassays were carried out in the Laboratory of Selectivity Studies, Department of Entomology of the Universidade Federal de Lavras – UFLA, Brazil, under controlled conditions (climatic chamber) at 25 ± 2º C, RH of 70 ± 10% with a 12 h photophase. The pesticides and doses in g or mL of i.a. L-1 were: thiamethoxam (0.5), imidacloprid (0.7), mineral oil (13.3), endosulfan (2.63) and dimethoate (0.48). Distilled water was used as a control. The sprayings of the pesticides were accomplished using a Potter’s tower. The parameters evaluated were: specimen survival after the application of the compounds, oviposition and eggs viability. Thiamethoxam, imidacloprid and endosulfan were the most harmful to the treated individuals. When sprayed on eggs, thiamethoxam increased the embryonic period length (7.1 days). Mineral oil was the only compound that did not affect the reproduction of C. montrouzieri. In function of the selectivity presented by mineral oil, it can be recommended to be used in integrated pest management on coffee plantations in association with this predator.

摘要：在咖啡种植园中，选择性化合物与天敌的协同作用是害虫综合治理（integrated pest management）的重要技术手段。本研究旨在实验室条件下，评估咖啡种植园常用数种农药对孟氏隐唇瓢虫（Cryptolaemus montrouzieri Mulsant）卵及成虫的致死与亚致死效应。生物测定试验于巴西拉夫拉斯联邦大学（Universidade Federal de Lavras – UFLA）昆虫学系选择性研究实验室开展，实验环境为可控条件（人工气候箱）：温度25±2℃，相对湿度70±10%，光周期12小时。供试农药及其有效成分（i.a.）剂量（单位：g或mL·L⁻¹）如下：噻虫嗪（thiamethoxam，0.5）、吡虫啉（imidacloprid，0.7）、矿物油（mineral oil，13.3）、硫丹（endosulfan，2.63）与乐果（dimethoate，0.48），以蒸馏水作为空白对照。农药喷施操作采用波特喷雾塔（Potter’s tower）完成。本次试验测定的指标包括：药剂处理后试虫存活率、产卵量以及卵孵化率。结果表明，噻虫嗪、吡虫啉与硫丹对处理试虫的伤害最为显著；当药剂喷施于卵块时，噻虫嗪会延长胚胎发育时长（7.1天）。矿物油是唯一不会影响孟氏隐唇瓢虫繁殖的供试化合物。鉴于矿物油所具备的选择性，其可与该捕食性天敌配合应用于咖啡种植园的害虫综合治理工作中。