Acaricidal effects of methyl benzoate against Tetranychus urticae Koch (Acari: Tetranychidae) on common crop plants

BACKGROUND Methyl benzoate (MB) is a small, hydrophobic organic compound isolated from the freshwater fern Salvinia molesta (Salviniales: Salviniaceae). It is used as a fragrance and flavor enhancer owing to its pleasant smell. It has also demonstrated potential as a green pesticide for various groups of insects. However, its effects on mites are yet to be studied. RESULTS Here, we assessed the acaricidal and repellent effects of MB against the two‐spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), under laboratory and greenhouse conditions. MB demonstrated concentration‐dependent contact toxicity against eggs and adults of the mite. A leaf‐dipping assay using 1% MB prevented the hatching of 92.7% of eggs and killed 100% of adults within 48 h of treatment. Concentration–mortality statistics were subjected to probit analysis, and the median lethal concentration (LC50) values for eggs and adults were 0.25% and 0.5%, respectively. Treatment with 1% MB showed the highest mortality (100%), with a median lethal time (LT50) estimated of 8.1 h. The efficacy of MB against adults of T. urticae on tomato plants under greenhouse conditions was 97.5% within 96 h post‐treatment. Further, MB showed significant repellent activity against adult females of T. urticae, although this declined with time. Spraying with 1% MB (three times per plant) was not phytotoxic to bean, cucumber, pepper, or tomato plants. CONCLUSION MB is highly acaricidal and repellent, but not phytotoxic, and is a promising green pesticide.