Chemical Composition of the Essential Oil of Tagetes minuta and Its Activity against Cochliomyia macellaria (Diptera: Calliphoridae)

Abstract

Background: Myiasis produced by Diptera larvae is responsible for the invasion of body tissues, seriously compromising animal welfare and causing significant economic losses to livestock. Cochliomyia macellaria is an important agent responsible for secondary myiasis, exacerbating the primary myiasis that could be already installed. Tagetes minuta essential oil (TMEO) is known for its anthelmintic and insecticidal properties, and it could be a sustainable alternative for the control and treatment of myiasis. Aims: This study aimed to evaluate TMEO activity on the third instar larvae (L3) of C. macellaria under laboratory conditions. Methods: Essential oils of T. minuta fresh aerial parts were extracted by hydrodistillation, characterized by gas chromatography coupling mass spectrometry (GC-MS) and tested against C. macellaria. Groups of 20 L3 were placed on filter paper impregnated with increasing (from 1.25 to 20%) TMEO concentrations, equivalent to 0.19 to 3.18 μl/cm2, solubilized in ethanol or acetone. Results: The major compounds of TMEO were dihydrotagetone (67.64%), trans-beta-ocimene (16.23%), trans-tagetone (10.14%) and verbenone (2.98%), respectively. The lethal concentrations of 50% were 0.678 and 0.580 for ethanol and 1.938 and 1.50 μl/cm2 for acetone, 24 and 48 h after TMEO exposure, respectively. The TMEO at 1.59 μl/cm2 caused 93.33% mortality to L3 after 48 h and the 0.7961 μl/cm2 caused an inhibition of 87.27% of L3 emergence. Conclusion: The TMEO had a time and concentration-dependent activity against L3 of C. macellaria; where optimal effects were observed using low concentrations.