Nine alkaloids (acridine, aristolochic acid, atropine, berberine, caffeine, nicotine, scopolamine, sparteine, and strychnine) were evaluated as feeding deterrents for gypsy moth larvae (Lymantria dispar (L.); Lepidoptera: Lymantriidae). Our aim was to determine and compare the taste threshold concentrations, as well as the ED(50) values, of the nine alkaloids to determine their potency as feeding deterrents. The alkaloids were applied to disks cut from red oak leaves (Quercus rubra) (L.), a plant species highly favored by larvae of this polyphagous insect species. We used two-choice feeding bioassays to test a broad range of biologically relevant alkaloid concentrations spanning five logarithmetic steps. We observed increasing feeding deterrent responses for all the alkaloids tested and found that the alkaloids tested exhibited different deterrency threshold concentrations ranging from 0.1 mM to 10 mM. In conclusion, it appears that this generalist insect species bears a relatively high sensitivity to these alkaloids, which confirms behavioral observations that it avoids foliage containing alkaloids. Berberine and aristolochic acid were found to have the lowest ED(50) values and were the most potent antifeedants.

中文翻译：

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不同生物碱浓度对吉普赛蛾幼虫 Lymantria dispar (L.) (Lepidoptera: Lymantriidae) 摄食行为的影响。

评估了九种生物碱（吖啶、马兜铃酸、阿托品、小檗碱、咖啡因、尼古丁、东莨菪碱、斯巴达碱和马钱子碱）对吉普赛蛾幼虫（Lymantria dispar (L.)；鳞翅目：Lymantriidae）的摄食威慑作用。我们的目的是确定和比较 9 种生物碱的味觉阈值浓度以及 ED(50) 值，以确定它们作为摄食威慑剂的效力。将生物碱应用于从红橡树叶 (Quercus rubra) (L.) 切下的圆盘上，这是一种深受这种杂食性昆虫幼虫喜爱的植物物种。我们使用两种选择的喂养生物测定来测试跨越五个对数步骤的广泛的生物学相关生物碱浓度。我们观察到所有测试的生物碱的摄食威慑反应都在增加，并发现所测试的生物碱表现出不同的威慑阈值浓度，范围从 0.1 mM 到 10 mM。总而言之，这种多面性昆虫似乎对这些生物碱具有相对较高的敏感性，这证实了它避免含有生物碱的叶子的行为观察。发现小檗碱和马兜铃酸具有最低的 ED(50) 值并且是最有效的拒食剂。