Assessing the non-target effects of LongRange® eprinomectin on dung-breeding insects

Endectocides are chemical compounds used as the active ingredient in VMPs (veterinary medicinal products) to treat and prevent the occurrence of ecto- and endoparasites in livestock. In the weeks following treatment, VMPs are excreted in dung as unmetabolized residues. The recent commercial product LongRange® (LR), developed for cattle (Bos taurus), contains the endectocide eprinomectin as the active ingredient. LR boasts a novel dual-peak and extended-release formulation with a second release of eprinomectin approximately 80 days post-injection. Our objective was to assess the concerns of this formulation having potentially detrimental effects on non-target insects who develop in dung. In this study, we placed artificially molded dung pats with varying concentrations of residue in the field for one week to be colonized by local dung insects. Following, we then assessed the ability of insects to develop in and emerge from the pats as adults. Preliminary results show complete eradication of Sepsis spp. flies up to 4 weeks following pat placement in the field for all residue concentrations tested. Supported by previous studies, this suggests that even very low concentrations of residue may have detrimental impacts causing delayed development or complete eradication of select species.