Toxicity of some essential oil formulations against the Mexican fruit fly Anastrepha ludens (Loew) (Diptera: Tephritidae)

• All EOs were toxic against A. ludens, with more than 50% mortality at a concentration of 1.5% (w/v) after 5 days.
• The most potent essential oil E. caryophyllus showed an LC50 of 3529 ppm on A. ludens adults.
• Composition of clove, thyme and basil was investigated and their major constituents were eugenol, thymol and estragole respectively.

Essential oils (EOs) extracted from Eugenia caryophyllus, Ocimum basilicum and Thymus vulgaris were evaluated for toxicity against adults of the fruit pest the Mexican fruit fly, Anastrepha ludens (Diptera: Tephritidae). The chemical composition of the EOs was also determined. The EOs of E. caryophyllus and O. basilicum contained primarily phenylpropanoids (77.58% and 72.63%, respectively), which were followed by benzoate esters (10.99%) and sesquiterpenes (6.22%) in E. caryophyllus and monoterpenes (16.65%) in O. basilicum. The EO of T. vulgaris was composed primarily of monoterpene hydrocarbons (89.39%). In ingestion toxicity assays, the EO of E. caryophyllus was the most toxic, with an LC50 of 3529 ppm, followed by the EOs of T. vulgaris and O. basilicum with LC50s of 5347 and 8050 ppm, respectively. At the highest concentration (1.5, 2.0 or 3.5% w/v), 100% mortality was observed with the three EOs in the ingestion toxicity assays. In general, the three EOs were significantly toxic to adult A. ludens. The development of a technology to incorporate the EOs into food bait could provide an alternative method to attract and kill A. ludens in field applications.