Canola is an important oilseed crop. It is attacked by different insect pests. Cabbage aphid ( Brevicoryne brassicae L.) is one the most destructive sucking insect pests of this crop. Its infestation affects the yield and quality of seed. Three different levels of nitrogen fertilizers, i.e., 120, 60 and 30 kg/hac, two environmentally safe insecticides i.e., emamectin benzoate and imidacloprid at three different application intervals i.e., 4, 8 and 12 days after first application (DAFA) were tested for management of cabbage aphid in canola. The experiment was laid out in a sub-sub plot design keeping nitrogen fertilizer levels as main plot, insecticides as sub plot and insecticide application intervals as sub-sub plots. Number of aphids per plant and canola seed yield for each combination was recorded. Total expenses from crop production till harvest were calculated on market rates of 2019. Benefit-cost ratio for each treatment combination was calculated. Lowest aphid infestation was fond for 4DAFA. Highest benefit-cost ratio (2.57) was recorded for imidacloprid applied at 4DAFA with 120 kg/ha nitrogen fertilizer. But for the management of cabbage aphid in environment friendly manner we recommend emamectin benzoate at 8DAFA with nitrogen level of 60 kg/hac giving slightly lower BCR (2.37).

中文翻译：

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在油菜 (Brassica napus L.) 作物生产中管理 Brevicoryne brasicae L. 的效益成本比评估

油菜籽是一种重要的油料作物。它受到不同害虫的攻击。甘蓝蚜虫（ Brevicoryne brasicae L.）是该作物最具破坏性的吸吮害虫之一。其侵染影响种子的产量和质量。测试了三种不同水平的氮肥，即 120、60 和 30 kg/hac，两种环境安全的杀虫剂，即甲维菌素苯甲酸酯和吡虫啉，在三个不同的施用间隔，即首次施用后的 4、8 和 12 天 (DAFA)油菜中甘蓝蚜虫的防治。试验在子子小区设计中进行，保持氮肥水平为主小区，杀虫剂为子小区，杀虫剂施用间隔为子子小区。记录每株植物的蚜虫数量和每种组合的双低油菜籽产量。从作物生产到收获的总费用按 2019 年的市场价格计算。计算每种处理组合的效益成本比。4DAFA 的蚜虫感染率最低。在 4DAFA 和 120 kg/ha 氮肥下施用吡虫啉的最高效益成本比 (2.57)。但是为了以环境友好的方式管理卷心菜蚜虫，我们建议使用 8DAFA 的 emamectin benzoate，氮含量为 60 kg/hac，BCR (2.37) 略低。