Repellent and insecticidal efficacy of a combination of dinotefuran, pyriproxyfen and permethrin (Vectra® 3D) against Culex pipiens in dogs

Culex pipiens is an important vector of pathogens of substantial medical and veterinary importance such as Dirofilaria immitis and Dirofilaria repens or the West Nile Virus. The control of these mosquitoes is therefore essential to control the transmission of mosquito-borne agents to humans and animals. A combination of dinotefuran, permethrin and pyriproxyfen (Vectra® 3D) has already shown its efficacy against Aedes aegypti. The aim of this study was to confirm the efficacy of this combination in repelling and killing another species of mosquito, Culex pipiens, after a single topical application to dogs.Twelve adult Beagle dogs with an equal receptivity to mosquitoes were included in the study and divided in two groups of six dogs: an untreated control group and a group treated with a combination containing 54 mg/mL dinotefuran + 4.84 mg/mL pyriproxyfen + 397 mg/mL permethrin (Vectra® 3D). All dogs were challenged with 80 Culex pipiens females for 90 ± 5 min on Days - 28, 1, 7, 14, 21 and 28. The treatment was applied once topically on Day 0. Count and engorgement determination of dead and live mosquitoes were performed after each exposure to treated and untreated dogs.Compared to control dogs, the spot-on formulation provided a repellent efficacy (anti-feeding effect) against mosquitoes of 98.9%, 98.8%, 98.6%, 96.7% and 97.9% on Days 1, 7, 14, 21 and 28 respectively. There was a significant difference (p ≤ 0.05) between the treated and controlled groups on every assessment day. The insecticidal efficacy on treated dogs at 90 min was 34.7%, 50.3%, 39.7%, 22.8% and 11.4% on Days 1, 7, 14, 21 and 28 respectively. There was a significant difference between the treated and controlled groups for live mosquitoes for all assessment days (p < 0.05).A single topical application of a combination of dinotefuran, permethrin and pyriproxyfen showed a significant repellent effect (i.e. > 96%) against Culex pipiens which lasted for 28 days. The results suggest that the Vectra® 3D spot-on solution could be used as an effective mosquito control strategy in dogs and is therefore recommended for use in a dirofilariosis prevention programme.