Bitter gourd (Momordica charantia L.) has compounds that repel insect pests. Unlike conventional pesticides, these compounds are eco-friendly and beneficial for human health. However the mechanisms by which these compounds repel insects and affect their physiology remains poorly known. Here we used Drosophila melanogaster (Meigen) to address these issues. We tested a wild strain, and a laboratory bred Canton S strain. Bitter gourd extract reduced the viability of developing flies, but did not affect survival in adults. Flies avoided bitter gourd extract in a food choice assay, and consumed a significantly low amount of food mixed with bitter gourd – indicating that it acts as an antifeedant. Transgenic flies with impaired aversive taste sensitive neurons showed a reduced aversion towards bitter gourd extract showing that these compounds act through the bitter sensitive gustatory neurons. Finally, flies also retained the memory of consuming bitter gourd extract for at least 24 hours, suggesting an additional cognitive mechanism for long term aversion. Our study provides the first evidence of bitter gourd compounds acting as antifeedants and also as potent reinforcers of aversive memory in drosophilids. We suggest that flies can be used to understand the physiological and neural mechanisms underlying the mode of action of other such phyto-extracts with the goal of developing potent but less harmful pest control formulations.

苦瓜 ( Momordica charantia L.) 含有可以驱除害虫的化合物。与传统杀虫剂不同，这些化合物是环保的，对人类健康有益。然而，这些化合物驱除昆虫并影响其生理的机制仍知之甚少。这里我们使用了黑腹果蝇(Meigen) 来解决这些问题。我们测试了一个野生菌株和一个实验室培育的 Canton S 菌株。苦瓜提取物降低了果蝇发育的活力，但不影响成虫的存活。苍蝇在食物选择试验中避免使用苦瓜提取物，并且食用与苦瓜混合的食物量显着低——这表明它起到了拒食的作用。厌恶味觉敏感神经元受损的转基因果蝇对苦瓜提取物的厌恶程度降低，表明这些化合物通过苦味敏感味觉神经元起作用。最后，苍蝇还保留了至少 24 小时食用苦瓜提取物的记忆，这表明长期厌恶的额外认知机制。我们的研究首次提供了苦瓜化合物作为拒食剂和果蝇厌恶记忆的强效强化剂的证据。我们建议苍蝇可用于了解其他此类植物提取物的作用模式背后的生理和神经机制，目的是开发有效但危害较小的害虫防治配方。