Lethal attraction of Raoiella indica Hirst (Acari: Tenuipalpidae) to Varronia curassavica Jacq. (Boraginaceae) essential oil.

The red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), is a major pest of coconut, banana and ornamentals in tropical America. Essential oils have proven bioactivity against pest arthropods and are highlighted for its potential in sustainable pest control. In this study, we evaluated the toxicity and sublethal effects of the essential oil extracted from Varronia curassavica Jacq. (Boraginaceae) [syn. Varronia (formerly Cordia) verbenacea DC] on R. indica. The essential oil from V. curassavica (accession VCUR 404) comprised 28 chemical constituents, with ar-turmerone being the predominant component. The oil exhibited high acute toxicity to adult R. indica, with a median lethal concentration (LC₅₀) of 1.9 mg/mL. In addition to toxicity, the oil significantly reduced the mite population growth rate, survival, and egg hatchability. Interestingly, despite its lethal and sublethal effects, adult mites showed a marked preference for oil-treated areas in a laboratory two-choice bioassay, suggesting an attractant-mediated mechanism that may lead to mortality. Overall, our findings highlight the essential oil of V. curassavica as a promising candidate for the development of environmentally sound strategies for the management of R. indica.