Efficacy of a combined insecticide–rodenticide product on ectoparasite and commensal rodent mortality

Abstract

BACKGROUND Ectoparasites may transfer zoonotic pathogens from rodents to humans or livestock when rodents are managed with rodenticides. This could be minimized using a product combining a rodenticide with a delayed action and a systemic insecticide/acaricide that rapidly kills ectoparasites. Such a combination was tested in commensal pest rodent species to assess efficacy and timing of responses in rodents, and fleas and ticks feeding on them. Ticks or fleas attached to rats (Rattus norvegicus) and house mice (Mus musculus domesticus) were exposed to a product containing brodifacoum (50 ppm) and fipronil (40 ppm) for three days. RESULTS 98–100% of fleas on treated rodents died within one to two days after first exposure, whereas >90% fleas survived on control rodents. The effect persisted for four or more days after bait uptake. Ticks started to succumb to the effect of the combination product within one day (mice) and within four days (rats) of first exposure, with all ticks dying by Day (D)8. Tick survival in control rodents was 90–100%. Rodent mortality began at D3 (rats) and D4 (mice) after first consumption of product and all were dead by D9 (rats) and D7 (mice). CONCLUSION This product effectively killed ectoparasites and rodents. Flea mortality was swift and complete, generally within one day of exposure, whereas it took ticks up to four days to die, but before the rats and house mice died. The combination product might help to prevent ectoparasites migrating from dying rodents to another host. Field trials are warranted. © 2020 Society of Chemical Industry

Synergistic effects of EP‐1 and ivermectin mixture (iEP‐1) to control rodents and their ectoparasites

“…4 In addition to causing high mortality in rodents, it increases the loads of flea or tick on the surviving population of rodents. 5 Previous studies indicated that fleas could survive for 5-15 days without sucking blood from hosts. 6 Therefore, it is necessary to develop a novel method that can provide synergistic control of rodents and vectors of diseases.…”

“…Traditional culling of rodents with rodenticides has been widely used to reduce their number, but it often suffers from various setbacks such as rapid population recovery after poisoning, high risk to non‐target animals and are against some people's beliefs 4 . In addition to causing high mortality in rodents, it increases the loads of flea or tick on the surviving population of rodents 5 . Previous studies indicated that fleas could survive for 5–15 days without sucking blood from hosts 6 .…”

The combined effect of bromadiolone and ivermectin (iBr) in controlling both rodents and their fleas

“…2001; Rust 2020; Hinds et al. 2021). A recent study indicated that baits containing 0.001% fipronil killed more than 90% of stickfast fleas ( Echidnophaga gallinacea ) and cat fleas ( Ctenocephalides felis ) on Norway rats (Jacob et al.…”

“…Therefore, it is necessary to kill fleas and ticks before killing rodents to minimize the spillover risk after rodent control (Leirs et al 2001;Hinds et al 2021). Adding insecticides into the baits of rodenticides has been proposed to control both rodents and ectoparasites (Leirs et al 2001;Rust 2020;Hinds et al 2021). For example, fipronil and imidacloprid are effective in killing fleas after oral intake by animals (Leirs et al 2001;Hinds et al 2021;Jacob et al 2021).…”

“…They may live in the environment and seek new hosts, which increases the risk of spillover of zoonotic disease to people. Therefore, it is necessary to kill fleas and ticks before killing rodents to minimize the spillover risk after rodent control (Leirs et al 2001;Hinds et al 2021). Adding insecticides into the baits of rodenticides has been proposed to control both rodents and ectoparasites (Leirs et al 2001;Rust 2020;Hinds et al 2021).…”