Repellent Effects of Andiroba and Copaiba Oils against Musca domestica (Common House Fly) and Ecotoxicological Effects on the Environment

Abstract

Background: The main challenge in raising cattle in Brazil is related to ectoparasites, that cause negative effects on milk and meat production, and in severe cases, animal death. Sheds known as crèches attracts large number insects mainly due to milk residues in the environment. The housefly is a major problem due to act as vectors of many other diseases, and so there is the possibility of control of infestations with natural products. Andiroba and copaiba oils may act as natural biocides, there are only a few studies on their effect on biological soil parameters. Therefore, this study aimed to evaluate the repellent effect of andiroba and copaiba oils against flies and on biological soil parameters.

Materials, Methods & Results: The repellency effect of oils of andiroba and copaiba was tested at a concentration of 5% in lambs shed maternity, containing 64 bays (1.8 m2). It was sprayed 30 mL per pen, where they were housed five lambs each. Pre-treatment counts were taken before the treatment (mean 46 per pen after Musca domestica), and post-treatment count was made on 2, 24 and 48 h. The data collected at 2 and 24 h was evaluated and the number of flies was reduced significantly (P < 0.001) in the pens treated with oil of copaiba and andiroba compared to control (untreated) pen. After 48 h, no difference was observed between treatments in relation to fly numbers (P > 0.05). Ecotoxicological test using increasing concentrations in the soil (0, 1, 5, 10, 25, 50, and 100 mg/kg) regarding changes in basal respiration (C-CO2), and survival and reproduction of springtails (Folsomia candida). It was observed an increased amount of mineralized C-CO2 until the day 10 of incubation for both oils without inhibition of the microbial respiratory process in any dose. The copaiba oil showed higher amounts of accumulated C-CO2 compared to andiroba oil in all studied concentrations (P < 0.05). In tests with mesofauna organisms, none of the evaluated concentrations of the two oils showed no negative effect on the survival of springtails (P > 0.05), the same was observed for the reproduction results, where there was no reduction in the number of juveniles (P > 0.05).

Discussion: According literature, andiroba and copaiba oils have repellent effect against domestic fly when sprayed onto infected cow’s horn fly, similar results also were reported in vitro tests against M. domestica larvae using andiroba oil and noted 80% larval mortality. The use of natural products in disease control is growing, but its impacts on the environment are not known, so in addition to suggesting therapies it is important to be concerned with ecotoxicological tests. Researchers showed an effect of Eucalyptus globulus essential oil on F. candida and reported 76% reduction in its survival rate at concentration of 60 mg/kg soil.  Basal soil respiration is a sensitive indicator that quickly reveals changes in the environmental conditions that affect microbial activity, and the data presented herein reveal an increase in the respiration of microorganisms depending on the amount of oil added to the soil.  The essential oils of copaiba and andiroba have repellent effect against Musca domestica, and did not show any toxicity to inhibit microbial activity in the soil. In addition, the presence of the oils in the soil did not affect the survival and reproduction of springtails Folsomia candida.