Efficacy of Limonene, ±-Terpinene, Terpinolene and ²-Pinene essential oils on larval stages of Cochliomya hominivorax in in vitro and in vivo tests.

Abstract

The fly Cochliomyia hominivorax, commonly known as blowfly and its larval form, myiasis, is commonly known as ''bicheira''. Flies lay their eggs on fresh, open wounds, for example: in the belly button of a newborn bovine that has not been healed properly, in dehorns, in castrations, or in wounds from fighting with other animals or on the fence and cause economic lost. Flies are also attracted to blood and wound secretions and even the odors of the infestation itself. Nowadays there are treatments to prevent myiasis, however, these drugs have been ineffective. This work presents the proposal to test the larvicidal effect of essential oils in in vitro and in vivo tests on C. hominivorax larvae. Natural products have been a new therapeutic proposal against ectoparasites, covering a public interested in less use of medicines either out of necessity (in the case of organic production) or because commercial ectoparasiticides fail in efficacy. Essential oils are of great importance for pharmaceutical, perfumery and cosmetics, household cleaning products, medicines and repellents and belong to the chemical group of terpenes, which have been proven to have an insecticidal, antibacterial, fungicidal and ectoparasiticide effect. The terpenes to be studied are: D-Limonene, ±-Terpinene, Terpinolene, ²-Pinene. They were chosen because they have common characteristics such as low cost and are easily found, as they come from plants with established agriculture (limonene comes from citrus, and the other terpenes come from pine trees). The in vitro test will consist in the evaluation of the toxicity of the oils in larvae of the first (L1), second (L2) and third (L3) stage of the isolate of C. hominivorax kept in the laboratory of Parasitology of the Instituto de Zootecnia de Nova Odessa-SP. The oil that presents the best efficacy in in vitro tests by determining its lethal concentration 50% (LC50) will be evaluated in an in vivo test in animals previously artificially infested with C. hominivorax larvae deposited in surgically performed wounds. The oil will be added to an ointment based on carnauba wax. The larvicidal and repellency effects of this ointment will be evaluated. It is expected with this study, to identify a possible natural formulation with larvicidal and repellent activity, after all, this fly in the current scenario generates economic losses and risk to the health of the animal.