Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2018
Publication Date: 5/21/2018
Citation: Feng, Y., Chen, J., Zhang, A. 2018. Commercially available natural benzyl esters and their synthetic analogs exhibit different toxicities against insect pests. Scientific Reports. https://doi.org/10.1038/s41598-018-26242-6.
Interpretive Summary: Previously, we reported that methyl benzoate (MB), a naturally – occurring volatile organic compound (VOC) existing as a floral fragrance in many plants, exhibited potent toxicity against several insect pests. In this study, we evaluated the bioactivity of MB along with 14 other analogs (9 of which occur naturally) against several insect pests. Results demonstrate that the MB analogs exhibit varying toxicities against these pests. The structure of MB shares the same chemical skeleton as DEET, the gold standard in arthropod repellency testing. They differ by the methyl ester in MB (DEET is diethylamide) and a methyl substitution on benzene ring in DEET. DEET does not have potent insecticidal properties; it does deter/repel insects. However, the way in which DEET elicits the repellent effect in target organisms is still a mystery. Our behavior bioassays show that MB and its analogs kill insects through contact exposures. Due to the chemical structure similarity with DEET, understanding the structure – activity relationship (SAR) of the MB analogs will be useful information for the discovery of the mode and mechanistic actions of DEET as an insect repellent. Further, it will allow researchers to modify the chemical structure of the MB molecule to develop pesticides that are more efficient for farmers to control insect pests.
Technical Abstract: Benzyl methyl ester, also known as methyl benzoate (MB), is a volatile organic compound that exists naturally as a floral fragrance in many plants. It also exhibits potent toxicity against several insect pests. The arthropod repellent, DEET, is also a benzyl ester. They share the same chemical skeleton; differing by the diethylamide ester and a methyl group found on the benzene ring in DEET. However, DEET does not kill insects; instead, it deters or repels them. How DEET causes the repellent effect in target organisms is still a mystery. Our behavior bioassays show that MB and some its naturally – occurring as well as synthetic analogs kill insects in different life stages through contact exposures. Both ester moiety and aromatic substitution of MB analogs can greatly affect toxicity. Due to the structural similarity to DEET, exploring the structure – activity relationship (SAR) of the MB analogs will provide useful information for the discovery of the mode and mechanistic actions of DEET as an insect repellent. In addition, the SAR will allow researchers to modify the chemical structure of the MB molecule, leading to the development of more efficient, safe, and environmentally – friendly green pesticides.