Comparative in vitro evaluation of contact activity of fluralaner, spinosad, phoxim, propoxur, permethrin and deltamethrin against the northern fowl mite, Ornithonyssus sylviarum.

BackgroundNorthern fowl mites (Ornithonyssus sylviarum) are obligate hematophagous ectoparasites of both feral birds and poultry, particularly chicken layers and breeders. They complete their entire life-cycle on infested birds while feeding on blood. Infestations of O. sylviarum are difficult to control and resistance to some chemical classes of acaricides is a growing concern. The contact susceptibility of O. sylviarum to a new active ingredient, fluralaner, was evaluated, as well as other compounds representative of the main chemical classes commonly used to control poultry mite infestations in Europe and the USA.MethodsSix acaricides (fluralaner, spinosad, phoxim, propoxur, permethrin, deltamethrin) were dissolved and serially diluted in butanol:olive oil (1:1) to obtain test solutions used for impregnation of filter paper packets. A carrier-only control was included. Thirty adult northern fowl mites, freshly collected from untreated host chickens, were inserted into each packet for continuous compound exposure. Mite mortality was assessed after incubation of the test packets for 48 h at 75% relative humidity and a temperature of 22 °C.ResultsAdult mite LC50 /LC99 values were 2.95/8.09 ppm for fluralaner, 1587/3123 ppm for spinosad, 420/750 ppm for phoxim and 86/181 ppm for propoxur. Permethrin and deltamethrin LC values could not be calculated due to lack of mortality observed even at 1000 ppm.ConclusionsNorthern fowl mites were highly sensitive to fluralaner after contact exposure. They were moderately sensitive to phoxim and propoxur, and less sensitive to spinosad. Furthermore, the tested mite population appeared to be resistant to the pyrethroids, permethrin and deltamethrin, despite not being exposed to acaricides for at least 10 years

The acaricidal speed of kill of orally administered fluralaner against poultry red mites (Dermanyssus gallinae) on laying hens and its impact on mite reproduction

Abstract Background Dermanyssus gallinae, the poultry red mite, is a growing threat to chickens in poultry farms. This nocturnal hematophagous ectoparasite has a rapid rate of proliferation with a negative impact on the birds’ health, welfare and productivity resulting in severe economic consequences for poultry farmers. A study was performed with fluralaner, a novel systemic ectoparasiticide, to evaluate its effect on mite vitality and reproduction after oral administration to laying hens. Methods Sixteen healthy hens were randomly allocated to two study groups (n = 8). One group was orally treated with fluralaner by gavage at a dose of 0.5 mg/kg bodyweight twice 7 days apart. The negative control group received no treatment. Hens in each group were repeatedly infested with approximately 200 unfed adult D. gallinae at 1, 5, 8, 12, 15, 19, 22 and 26 days after the initial administration. After infestation and feeding for 2.5 h, 25 engorged mites per hen were collected and incubated in tubes. Mites were assessed for vitality (dead/live) at 4, 8, 12, and 24 h after each infestation. Tubes containing eggs and/or living mites were incubated another 8 days for assessment of mite reproductive capacity. Results Fluralaner demonstrated a fast speed of kill in mites within 4 h post-infestation for 12 days after treatment initiation. An efficacy (mite mortality) of 98.7–100% was achieved. At 15 days after treatment initiation, 100% efficacy was achieved within 24 h post-infestation, and no mite oviposition occurred during this period. Nineteen days after treatment initiation, the mites’ ability to generate nymphs was reduced by 90.8%, which decreased to < 24.1% at later infestations. Conclusions Fluralaner administered orally to hens twice, 7 days apart, provides efficacy against experimental poultry red mite infestation for at least 2 weeks. The demonstrated rapid speed of kill results in substantial depletion of the mites’ oviposition and suggests that fluralaner can be an effective tool in the control of D. gallinae, one of the most urgent problems in poultry farms

Fluralaner activity against life stages of ticks using Rhipicephalus sanguineus and Ornithodoros moubata IN in vitro contact and feeding assays

Abstract Background Fluralaner is a novel isoxazoline eliciting both acaricidal and insecticidal activity through potent blockage of GABA- and glutamate-gated chloride channels. The aim of the study was to investigate the susceptibility of juvenile stages of common tick species exposed to fluralaner through either contact (Rhipicephalus sanguineus) or contact and feeding routes (Ornithodoros moubata). Methods Fluralaner acaricidal activity through both contact and feeding exposure was measured in vitro using two separate testing protocols. Acaricidal contact activity against Rhipicephalus sanguineus life stages was assessed using three minute immersion in fluralaner concentrations between 50 and 0.05 μg/mL (larvae) or between 1000 and 0.2 μg/mL (nymphs and adults). Contact and feeding activity against Ornithodoros moubata nymphs was assessed using fluralaner concentrations between 1000 to 10−4 μg/mL (contact test) and 0.1 to 10−10 μg/mL (feeding test). Activity was assessed 48 hours after exposure and all tests included vehicle and untreated negative control groups. Results Fluralaner lethal concentrations (LC50, LC90/95) were defined as concentrations with either 50%, 90% or 95% killing effect in the tested sample population. After contact exposure of R. sanguineus life stages lethal concentrations were (μg/mL): larvae - LC50 0.7, LC90 2.4; nymphs - LC50 1.4, LC90 2.6; and adults - LC50 278, LC90 1973. After exposure of O. moubata nymphs to fluralaner lethal concentrations were (μg/mL): contact exposure - LC50 720, LC95 1133; and feeding exposure- LC50 0.00007, LC95 0.09. Conclusions Fluralaner demonstrates potent in vitro acaricidal activity against all life stages of the brown dog tick, R.sanguineus. The testing of fluralaner contact and feeding routes using O. moubata nymphs demonstrates a high acaricidal activity in both exposure routes

Comparative in vitro evaluation of contact activity of fluralaner, spinosad, phoxim, propoxur, permethrin and deltamethrin against the northern fowl mite, Ornithonyssus sylviarum.

BackgroundNorthern fowl mites (Ornithonyssus sylviarum) are obligate hematophagous ectoparasites of both feral birds and poultry, particularly chicken layers and breeders. They complete their entire life-cycle on infested birds while feeding on blood. Infestations of O. sylviarum are difficult to control and resistance to some chemical classes of acaricides is a growing concern. The contact susceptibility of O. sylviarum to a new active ingredient, fluralaner, was evaluated, as well as other compounds representative of the main chemical classes commonly used to control poultry mite infestations in Europe and the USA.MethodsSix acaricides (fluralaner, spinosad, phoxim, propoxur, permethrin, deltamethrin) were dissolved and serially diluted in butanol:olive oil (1:1) to obtain test solutions used for impregnation of filter paper packets. A carrier-only control was included. Thirty adult northern fowl mites, freshly collected from untreated host chickens, were inserted into each packet for continuous compound exposure. Mite mortality was assessed after incubation of the test packets for 48&nbsp;h at 75% relative humidity and a temperature of 22&nbsp;°C.ResultsAdult mite LC50 /LC99 values were 2.95/8.09&nbsp;ppm for fluralaner, 1587/3123&nbsp;ppm for spinosad, 420/750&nbsp;ppm for phoxim and 86/181&nbsp;ppm for propoxur. Permethrin and deltamethrin LC values could not be calculated due to lack of mortality observed even at 1000&nbsp;ppm.ConclusionsNorthern fowl mites were highly sensitive to fluralaner after contact exposure. They were moderately sensitive to phoxim and propoxur, and less sensitive to spinosad. Furthermore, the tested mite population appeared to be resistant to the pyrethroids, permethrin and deltamethrin, despite not being exposed to acaricides for at least 10&nbsp;years

In vitro activity of fluralaner and commonly used acaricides against Dermanyssus gallinae isolates from Europe and Brazil

Abstract Background The poultry red mite Dermanyssus gallinae negatively impacts bird welfare and health, and interferes with egg production and quality, while emerging acaricide resistance limits control options. Fluralaner, a novel miticide for administration in drinking water, is approved for control of D. gallinae infestations. Mite sensitivity testing is relevant to gauge field isolate susceptibility to available treatments. Methods Thirteen D. gallinae isolates collected during 2014 through 2016 from farms in Germany, France, Spain and Brazil, and a 2001 laboratory-maintained isolate were used for acaricide contact sensitivity testing. Tested compounds were cypermethrin, deltamethrin, phoxim, propoxur, and the recently available acaricides, spinosad and fluralaner. In each study, at least one isolate was exposed to increasing concentrations of at least one acaricide. In one study, additional testing determined the sensitivity of the 2001 isolate to fluralaner using a mite-feeding test, and of fluralaner, phoxim and spinosad using an immersion test. At least two replicates were used for each dilution. Vehicle and untreated controls were also included. Results Based on 90% mortality (LC90) values, the laboratory isolate was susceptible to fluralaner (15.6–62.5 parts per million, ppm), phoxim ( 4000 ppm). An isolate from Spain demonstrated reduced sensitivity to phoxim, propoxur and deltamethrin; an isolate from Brazil showed reduced sensitivity to propoxur and cypermethrin. Mite LC90 when exposed to fluralaner by blood feeding was < 0.1 ppm. Conclusions Contact sensitivity testing indicated apparent resistance to at least one of phoxim, deltamethrin, cypermethrin and propoxur in 13 field isolates from Europe and Brazil. All isolates were highly susceptible to fluralaner. Fluralaner was approximately 1000 times more active by feeding than by contact. Fluralaner’s distinct mode of action and efficacy against isolates largely refractory to those acaricides, makes it a promising option for the control of D. gallinae infestations of poultry