Table_1_Control of tea aphids via attracting the parasitic wasp, Aphelinus sp. with synthetic semiochemicals.pdf

The tea aphid (Toxoptera aurantii Boyer de Fonscolombe) is an important tea plant pest insect worldwide. The parasitoid wasp, Aphelinus sp., is one of the most important natural enemies of the tea aphid in China. Unfortunately, Aphelinus sp. alone cannot effectively control the outbreaks of the aphid under natural conditions. In this study, 27 volatile compounds from tea aphid-injured tea shoots, tea flowers, aphid sex pheromones, or body rinses were selected and tested in Y-tube olfactometer assays to find potential attractants of the parasitoid wasp, Aphelinus sp. Based on the Y-tube assay results, the following three attractant mixtures were formulated and further tested in the field. Attractant-1 (HIPV-based) included trans-2-hexenal (10−6 g/ml), β-ionone (10−6 g/ml), allyl isothiocyanate (10−4 g/ml), trans-2-pentenal (10−2 g/ml), and jasmone (10−2 g/ml) at equal loading volume of their solutions. Attractant-2 (with aphid sex-pheromone and body rinse compounds) included nepetalactone (10−6 g/ml), 2,5-hexanedione (10−4 g/ml), benzaldehyde (10−2 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Attractant-3 (partial combination of Attractant-1 and Attractant-2) included nepetalactone (10−4 g/ml), benzaldehyde (10−2 g/ml), jasmone (10−2 g/ml), trans-2-hexenal (10−6 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Field trials showed that Attractant-3 was much more attractive to the parasitic wasps than Attractant-1 and Attractant-2. From late August to late September the controlled release of Attractant-3 effectively attracted Aphelinus sp. to parasitize and colonize the aphid populations in the treated tea plantations, resulting in a progressive decrease of the tea aphid abundances/populations in the fall. The continued enhanced parasitism of overwintered aphids by Aphelinus sp. further reduced this population during the next spring tea harvest season. This approach may present an environmentally sound, non-insecticidal control tactic against tea aphids using synthetic semiochemicals.

茶蚜虫（Toxoptera aurantii Boyer de Fonscolombe）是全球范围内重要的茶树害虫。寄生蜂Aphelinus sp.是中国茶蚜虫最重要的天敌之一。遗憾的是，在自然条件下，Aphelinus sp.单独无法有效控制蚜虫的爆发。在本研究中，从受茶蚜虫侵害的茶芽、茶花、蚜虫性信息素或体液洗涤液中选出了27种挥发性化合物，并在Y型嗅觉仪测试中进行了检测，以寻找对寄生蜂Aphelinus sp.具有潜在吸引力的物质。基于Y型嗅觉仪的测试结果，制定了以下三种吸引混合物，并在田间进行了进一步测试。吸引剂-1（基于HIPV）包含等体积溶液的顺-2-己烯醛（10−6 g/ml）、β-紫罗兰酮（10−6 g/ml）、异硫氰酸烯丙酯（10−4 g/ml）、顺-2-戊烯醛（10−2 g/ml）和茉莉酮（10−2 g/ml）。吸引剂-2（含蚜虫性信息素和体液洗涤化合物）包含牛儿酮（10−6 g/ml）、2,5-己二酮（10−4 g/ml）、苯甲醛（10−2 g/ml）、二十烷（10−2 g/ml）和十七烷（10−2 g/ml），其溶液的装载体积相等。吸引剂-3（吸引剂-1与吸引剂-2的部分组合）包含牛儿酮（10−4 g/ml）、苯甲醛（10−2 g/ml）、茉莉酮（10−2 g/ml）、顺-2-己烯醛（10−6 g/ml）、二十烷（10−2 g/ml）和十七烷（10−2 g/ml），其溶液的装载体积相等。田间试验表明，吸引剂-3对寄生蜂的吸引力远大于吸引剂-1和吸引剂-2。从八月末至九月末，吸引剂-3的持续释放有效地吸引了Aphelinus sp.寄生并定殖于处理过的茶园中的蚜虫种群，导致秋季茶蚜虫的丰度和/或种群数量逐渐减少。Aphelinus sp.对越冬蚜虫的持续增强寄生作用，在下一个春季茶叶收获季节进一步减少了这一种群。这种方法可能提供了一种环境友好、非杀虫剂的控制策略，用以利用合成信息素对抗茶蚜虫。