Ovicidal,larvicidal and oviposition repelling action of a nanoemulsion of citronella essential oil (Cymbopogon winterianus) on Cochliomyia hominivorax (Diptera: Calliphoridae)

Cochliomyia hominivorax is the dipteran that causes the worst and most serious types of myiasis in animals and humans in the Americas. They are parasitic affections caused by the massive infestation of larvae of this species on the tissues of living mammals. The routine treatment uses chemosynthetic products that have high toxicity and can cause several injuries to animal and human health, besides environmental contamination. The development of more friendly alternatives to the treatment of this disease is an important knowledge gap nowadays. Citronella (Cymbopogon winterianus) is the most widely cultivated medicinal plant in tropical and subtropical regions. Essential oils have a recognised repellent and larvicidal activity against a wide variety of insects. This work aimed to evaluate the repellent, ovicidal and larvicidal efficacy of a topical commercial formulation composed of 15% (w/v) nanoemulsified Citronella essencial oil (Nano Citronela Plus®) in in vitro trials on specimens of C. hominivorax created under laboratory conditions. Nano Citronela Plus® is an oil-in-water nanoemulsion obtained by high-pressure homogenization method. The composition of tested nanoemulsion was Cymbopogon winterianus essential oil, vanillin, caprylic/capric triglyceride, polysorbate 80, sorbitan oleate, tocopheryl acetate, sodium benzoate and water. Nano Citronela Plus® demonstrated 100% lethality on eggs and first and second stage larvae of C. hominivorax. Mortality in the larvae of third stage was 69.33% and inhibited the oviposition of C. hominivorax females. Nano Citronela Plus® proved to be a possible herbal alternative for the control and treatment of myiasis caused by C. hominivorax. In vivo studies may test this hypothesis.