Evaluation of the efficacy of topically administered imidacloprid + pyriproxyfen and orally administered spinosad against cat fleas (Ctenocephalides felis): Impact of treated dogs on flea life stages in a simulated home environment

Abstract

BackgroundCat fleas, Ctenocephalides felis, are one of the most common ectoparasites infesting dogs and their environments. This study evaluated the efficacy of imidacloprid + pyriproxyfen (PPF) (Advantage® II for Dogs) and spinosad (Comfortis®) against established C. felis populations in dogs’ simulated home environments.MethodsThirty Beagle dogs were randomly assigned to three groups of 10 dogs each and treated twice (Study Days 0 and 28) with imidacloprid + PPF, spinosad tablets, or a negative control (untreated). Dogs were housed individually in controlled simulated home environments capable of supporting the flea life cycle. Flea infestations were established in these environments by infesting each dog with 100 adult cat fleas on Study Days −21, -16 and 1. The impact of the treatments on fleas in the dogs’ environments were assessed by collecting floor mat samples from each simulated home environment, incubating them for 32 days, and counting the number of emerging adult fleas. On Study Days 7, 14, 21, 28, 35, 42, 49 and 56, after collection of the cocoa matting samples, each dog was infested with an additional 5 ± 1 fleas to maintain the environmental infestations. Flea comb counts on dogs were conducted on Study Days 0 (pretreatment) and 63.ResultsFrom Study Days 7–28, flea infestations in the imidacloprid + PPF environments were significantly lower (p < 0.03) than those in the spinosad environments. Following the second treatment, flea infestations in all the imidacloprid + PPF environments fell to zero for the remainder of the study. In contrast, flea infestations persisted in some of the spinosad environments through the study’s end.On Study Day 63 all 10 dogs treated with imidacloprid + PPF were flea free, while only one of the 10 spinosad treated dogs was flea free. Flea counts on the other 9 spinosad treated dogs ranged from 3 to 46 fleas/dog (geometric mean = 8.6). A mean of 405 adult fleas/animal were recovered from the control dogs on Study Day 63.ConclusionFlea infestations in environments of dogs treated with imidacloprid + PPF declined more rapidly than in those containing dogs treated with spinosad. Flea infestations were completely eliminated by Study Day 56 in environments of dogs treated with imidacloprid + PPF, but persisted through the study’s end in some of environments of dogs treated with spinosad.

A field trial of spinosad for the treatment and prevention of flea infestation in shepherd dogs living in close proximity to flea-infested sheep

“…The high percent efficacy of spinosad for the treatment and prevention of flea infestations (>98 % and >99 % using arithmetic and geometric means, respectively) is comparable to the efficacy of this molecule that has been reported in most studies where dogs were experimentally infested by C. canis [ 10 ] or C. felis [ 5 , 6 , 9 , 19 ], as well as after experimental infestation with C. felis of dogs in a home simulated environment [ 13 ]. Also, the reduction of flea counts witnessed in the present study was very similar to those reported previously in field trials of spinosad [ 5 , 14 , 15 ], spinosad-milbemycin oxime combination [ 20 ] and spinosad in combination with an amitraz collar [ 21 ].…”

“…However, the increased relative abundance of C. canis in sheep at days 28 and 84 does not seem to be in favor of this explanation. The fast adult flea killing activity of spinosad has a strong negative impact on egg production so that new adult flea emergence progressively declines when all dogs (and obviously other possible hosts) are treated [ 9 , 12 , 13 ]. In our study, administration of spinosad in some of the dogs in each farm may have reduced the relative abundance of C. canis , which was the predominant flea species at day 0, thus leading to an increased relative abundance of P. irritans .…”

“…Spinosad is a mixture of spinosyns A and D that, after ingestion by the insect during blood meal, targets their nicotinic acetylcholine receptors and gamma-aminobutyric acid neurotransmission, leading to hyperexcitation and death [ 5 – 7 ]. When administered orally, spinosad is effective for the treatment of pre-existing and for the prevention of new infestations by C. felis and C. canis under laboratory conditions [ 5 , 6 , 8 – 12 ], by C. felis in a simulated home environment [ 13 ] and by undetermined flea species under field conditions [ 5 , 14 , 15 ] for up to 4 weeks.…”

Development of advantus™(imidacloprid) soft chewable tablets for the treatment of Ctenocephalides felis infestations on dogs

“…The combination of imidacloprid and moxidectin (Advantage Multi®, Advocate®) is used for prevention of heartworm disease [ 16 ] and for treatment of fleas, intestinal nematodes [ 17 ], sarcoptic mange [ 18 ], demodex mange [ 19 ] and ear mites [ 20 ]. Imidacloprid combined with pyriproxyfen (Advantage II®) extended the activity against all life stages of fleas [ 21 ].…”

Evaluation of the Efficiency of Certain Attractive Toxic Baits for the Control of the House Fly, Musca domestica (Diptera: Muscidac)

“…Previous works mentioned that LC 50 (84 Nano-gram/L) of imidacloprid to larvae of Aedes aegypti. Uragayala et al evaluated the Larvicidal effect of neonicotinoid insecticides against susceptible and resistant mosquito's strains [82][83][84][85][86][87][88][89][90][91][92][93][94][95][96].…”