Association of Varroa destructor females in multiply infested cells of the honeybee Apis mellifera.

The genetic diversity of Varroa destructor (Anderson & Trueman) is limited outside its natural range due to population bottlenecks and its propensity to inbreed. In light of the arms race between V. destructor and its honeybee (Apis mellifera L.) host, any mechanism enhancing population admixture of the mite may be favored. One way that admixture can occur is when two genetically dissimilar mites coinvade a brood cell, with the progeny of the foundresses admixing. We determined the relatedness of 393 pairs of V. destructor foundresses, each pair collected from a single bee brood cell (n = five colonies). We used six microsatellites to identify the genotypes of mites coinvading a cell and calculated the frequency of pairs with different or the same genotypes. We found no deviation from random coinvasion, but the frequency of cells infested by mites with different genotypes was high. This rate of recombination, coupled with a high transmission rate of mites, homogenized the allelic pool of mites within the apiary.

Seasonal cycle of inbreeding and recombination of the parasitic mite Varroa destructor in honeybee colonies and its implications for the selection of acaricide resistance.

Varroa destructor is the most devastating parasite of the Western honeybee, Apis mellifera. In the light of the arm race opposing the host and its parasite, the population dynamics and genetic diversity of these organisms are key parameters. However, the life cycle of V. destructor is characterized by extreme inbreeding due to full sibling mating in the host brood cells. We here present an equation reflecting the evolution of inbreeding in such a clonal system, and compare our predictions with empirical data based on the analysis of seven microsatellite markers. This comparison revealed that the mites perform essentially incestuous mating in the beginning of the brood season. However, this pattern changes with the development of mite infestation. Despite the fact that the overall level of genetic diversity of the mites remained low through the season, multiple inbred lineages were identified in the mites we sampled in June. As a response to the decrease of brood availability and the increase of the parasite population in parallel in the colonies, these lineages recombined towards the end of the season as mites co-infest brood cells. Our results suggest that the ratio of the number of mite per brood cell in the colony determines the genetic structure of the populations of V. destructor. This intracolonial population dynamics has great relevance for the selection of acaricide resistance in V. destructor. If chemical treatments occur before the recombination phase, inbreeding will greatly enhance the fixation of resistance alleles at the colony level.

Efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs.

BACKGROUND: The studies reported here were conducted to ascertain the efficacy of imidacloprid/flumethrin incorporated in a slow-release matrix collar, against infestations of dogs by fleas, ticks, mites and lice. Efficacy was evaluated against the flea Ctenocephalides felis felis, the ticks Rhipicephalus sanguineus, Ixodes ricinus, Ixodes scapularis, Dermacentor reticulatus and Dermacentor variabilis, the mite Sarcoptes scabiei and the biting louse Trichodectes canis. METHODS: Groups of collar-treated dogs (n = 7-10) were infested with fleas and/or ticks at monthly intervals at least, over a period of up to 8 months. Efficacy against fleas was evaluated 24 to 48 h after treatment and 24 h after each re-infestation. Efficacy against ticks was evaluated at 48 h (acaricidal), 6 h (repellent) and 48 h (sustained) after infestation. The effect of regular shampooing or immersion in water on the efficacy of the collars was also tested. Efficacy against flea larvae was assessed by incubating blanket samples after dog contact with viable flea eggs. Effectiveness against lice and mites was evaluated after treatment of naturally infested animals. With the exception of the mites, efficacy was calculated by comparison with untreated negative control groups. RESULTS: Efficacy against fleas (24 h) generally exceeded 95%, and against flea larvae it exceeded 99% for 8 months. Sustained acaricidal (48 h) efficacy, covering a period of 8 months was 100% against I. ricinus, starting 2 days after treatment (in vivo), and 100% against I. scapularis (in vitro), above 97% against R. sanguineus, generally above 97% against D. reticulatus and above 90% for D. variabilis.Repellent (6 h) efficacy 2 days after treatment and continuing for 8 months was consistently 100% against I. ricinus, and above 90% against R. sanguineus.Regular shampooing affected efficacy against fleas and ticks to a lesser extent than regular immersion in water.The collars eliminated Trichodectes canis within 2 days and Sarcoptes scabiei within 3 months. CONCLUSION: The rapid insecticidal and acaricidal properties of the medicated collars against newly-acquired infestations of fleas and ticks and their sustained high levels of preventive efficacy have been clearly shown. Consequently they have the potential to prevent the transmission of vector-borne diseases and other conditions directly associated with infestation throughout an entire season of parasite abundance.

Efficacy of an imidacloprid/flumethrin collar against fleas and ticks on cats.

BACKGROUND: The objectives of the studies listed here were to ascertain the therapeutic and sustained efficacy of 10% imidacloprid (w/w) and 4.5% flumethrin (w/w) incorporated in a slow-release matrix collar, against laboratory-infestations of fleas and ticks on cats. Efficacy was evaluated against the flea Ctenocephalides felis felis, and the ticks Ixodes ricinus, Amblyomma americanum and Rhipicephalus turanicus. The number of studies was so large that only a general overview can be presented in this abstract. METHODS: Preventive efficacy was evaluated by infesting groups of cats (n = 8-10) with C. felis felis and/or I. ricinus, A. americanum or R. turanicus at monthly intervals at least, for a period of up to 8 months. Efficacy against fleas was evaluated 24 to 48 h after treatment and 24 h after infestation, and against ticks at 6 h (repellent) or 48 h (acaricidal) after infestation. Efficacy against flea larvae was evaluated over a period of 8 months by incubating viable flea eggs on blanket samples after cat contact. In all cases efficacy was calculated by comparison with untreated negative control groups. RESULTS: Efficacy against fleas (24 h) generally exceeded 95% until study termination. In vitro efficacy against flea larvae exceeded 92% until Day 90 and then declined to 67% at the conclusion of the study on Day 230.Sustained acaricidal (48 h) efficacy over a period of eight months was consistently 100% against I. ricinus from Day 2 after treatment, 100% against A. americanum, except for 98.5% and 97.7% at two time-points, and between 94% and 100% against R. turanicus.From Day 2 until 8 months after treatment the repellent (6 h), efficacy was consistently 100% against I. ricinus, and between 54.8% and 85.4% against R. turanicus. CONCLUSION: The rapid insecticidal and acaricidal properties of the medicated collars against newly- acquired infestations of fleas and ticks and their sustained high levels of preventive efficacy have been clearly demonstrated. Taking into account the seasonality of fleas and ticks, the collars have the potential to prevent the transmission of vector-borne diseases and other conditions directly associated with infestation throughout the season of parasite abundance.

The synergistic action of imidacloprid and flumethrin and their release kinetics from collars applied for ectoparasite control in dogs and cats.

BACKGROUND: The control of tick and flea burdens in dogs and cats has become essential to the control of important and emerging vector borne diseases, some of which are zoonoses. Flea worry and flea bite hypersensitivity are additionally a significant disease entity in dogs and cats. Owner compliance in maintaining the pressure of control measures has been shown to be poor. For these reasons efforts are continuously being made to develop ectoparasiticides and application methods that are safe, effective and easy to apply for pet owners. A new polymer matrix collar has recently been developed which is registered for 8 months use in cats and dogs. The basic properties of this collar have been investigated in several in vitro and in vivo studies. METHODS: The effects of imidacloprid, flumethrin and the combination were evaluated in vitro by means of whole cell voltage clamp measurement experiments conducted on isolated neuron cells from Spodoptera frugiperda. The in vitro efficacy of the two compounds and the combination against three species of ticks and their life stages and fleas were evaluated in a dry surface glass vial assay. The kinetics of the compounds over time in the collar were evaluated by the change in mass of the collar and measurement of the surface concentrations and concentrations of the actives in the collar matrix by HPLC. Hair clipped from collar treated dogs and cats, collected at various time points, was used to assess the acaricidal efficacy of the actives ex vivo. RESULTS: An in vitro isolated insect nerve model demonstrated the synergistic neurotoxic effects of the pyrethroid flumethrin and the neonicotinoid imidacloprid. An in vitro glass vial efficacy and mortality study against various life stages of the ticks Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus and against the flea (Ctenocephalides felis) demonstrated that the combination of these products was highly effective against these parasites. The release kinetics of these actives from a neck collar (compounded with 10% imidacloprid and 4.5% flumethrin) was extensively studied in dogs and cats under laboratory and field conditions. Acaricidal concentrations of the actives were found to be consistently released from the collar matrix for 8 months. None of the collar studies in dogs or cats were associated with any significant collar related adverse event. CONCLUSION: Here we demonstrated the synergism between the pyrethroid flumethrin and the neonicotinoid imidacloprid, both provided in therapeutically relevant doses by a slow release collar matrix system over 8 months. This collar is therefore a convenient and safe tool for a long-term protection against ectoparasites.

Efficacy of emodepside plus toltrazuril (Procox(®) oral suspension for dogs) against Toxocara canis, Uncinaria stenocephala and Ancylostoma caninum in dogs.

The efficacy of emodepside plus toltrazuril (Procox® oral suspension for dogs) against different species of gastrointestinal nematodes (Toxocara canis, Ancylostoma caninum, Uncinaria stenocephala) was evaluated in nine randomised,blinded and placebo-controlled laboratory studies in naturally or experimentally infected dogs. The product was used at the proposed minimum dose of 0.45 mg emodepside and 9 mg toltrazuril per kg body weight. Efficacy was calculated based on worm counts after necropsy. Worm burdens in the control dogs ranged between 0 and 409 worms of the respective stage for T. canis and between 4 and 655 worms for hookworms. The studies demonstrated 100 % efficacy of emodepside/toltrazuril suspension against mature adult, ≥ 94.7 %efficacy against immature adult and 99.3 % efficacy against the L4 larval stage of T. canis. The efficacy against mature adult A. caninum was ≥ 99.5 % and the efficacy against mature adult U. stenocephala was 100 %. All differences between treatment and control groups were statistically significant and no gender effect was found. It can be concluded that the emodepside/toltrazuril suspension represents a safe and highly effective product in dogs with nematode (T. canis, hookworms) infection.

Efficacy of emodepside plus toltrazuril suspension (Procox(®) oral suspension for dogs) against prepatent and patent infection with Isospora canis and Isospora ohioensis-complex in dogs.

Three randomised, blinded and placebo-controlled laboratory studies were conducted to evaluate the efficacy of emodepside plus toltrazuril suspension (Procox(®) suspension for dogs) against Isospora canis and Isospora ohioensis-complex. Unweaned puppies were experimentally infected with sporulated oocysts of I. canis and/or I. ohioensis-complex. In each study, one group was treated during prepatency (2 or 4 days post infection) while dogs in the second group were treated individually after the onset of oocyst excretion of the respective coccidia species. The dogs were treated with the minimum therapeutic dose of 0.45 mg emodepside and 9 mg toltrazuril per kg body weight. Daily faecal oocyst counts from both groups were compared to placebotreated control groups to determine efficacy.Dogs treated during prepatent I. canis or I. ohioensis-complex infection showed significantly lower oocyst counts for up to 12 days compared to the control group. Oocyst counts were reduced by 90.2 - 100 % while the control groups continued to exhibit an adequate infection, except for one study where efficacy against prepatent I. canis infection faded 13 days after treatment. Following treatment of patent I. canis or I. ohioensis-complex infections, significantly lowered oocyst counts were observed for up to 9 days compared to the control group. Faecal oocyst counts were reduced by 91.5 - 100 %. In all three studies the number of days with diarrhoea was significantly lower when dogs were treated during prepatent Isospora spp. infection compared to the control groups. No adverse drug reactions were observed during the studies. In conclusion, the studies demonstrated that emodepside plus toltrazuril suspension is an efficient coccidiocide for dogs.

Field evaluations of the efficacy and safety of Emodepside plus toltrazuril (Procox® oral suspension for dogs) against naturally acquired nematode and Isospora spp. infections in dogs.

Three controlled, blinded and randomised multicentre field studies evaluated the efficacy and safety of a new formulation containing emodepside plus toltrazuril (Procox® suspension for dogs) against naturally acquired parasite infections in dogs. In two studies dogs positive for gastrointestinal nematodes and/or Isospora spp. were treated with emodepside/toltrazuril suspension (at least 0.45 mg emodepside plus 9 mg toltrazuril per kg body weight) or a reference product containing either milbemycin oxime plus praziquantel (Milbemax®) or sulfadimethoxine (Kokzidiol SD®) at recommended dose rates. The third study investigated efficacy against prepatent natural Isospora spp. infections in comparison to an untreated control group by enrolling Isospora- negative dogs that were at risk to develop a patent infection during the study.No suspected adverse drug reactions were observed in any of the 403 dogs enrolled in the three studies including 234 dogs treated with emodepside/toltrazuril suspension. In dogs treated with emodepside/toltrazuril suspension against nematode infection faecal egg counts were reduced by 100 % (reference product: 99.7 %). Similarly, in the dogs that had been treated against patent Isospora spp. infection, faecal oocyst counts were reduced by 100 % (reference product: 99.0 %). In both studies, statistical analysis demonstrated non-inferiority and even superiority to the reference products (p ≤ 0.009). Dogs treated with emodepside/toltrazuril suspension during suspected prepatent Isospora spp. infection had 98.7 % lower faecal oocyst counts after treatment compared to untreated dogs (p < 0.0001).The studies demonstrated that emodepside/toltrazuril suspension is safe and highly efficacious against nematodes and Isospora spp. under field conditions.

Efficacy of Procox® oral suspension for dogs (0.1% emodepside and 2% toltrazuril) against experimental nematode (Toxocara cati and Ancylostoma tubaeforme) infections in cats.

Two exploratory studies were performed to determine the optimum therapeutic dose of Procox(®) for the removal of experimental infection with mature adult Toxocara (T.) cati and Ancylostoma (A.) tubaeforme in kittens. Procox(®) is a new oral suspension containing a combination of the nematocidal and coccidiocidal active principles emodepside (0.1 %) and toltrazuril (2 %).In the first study, 18 eight-weeks-old kittens were inoculated with 450 L3 larvae of T. cati. 56 days after infection, the kittens were allocated to three treatment groups and were treated with 0.5 mg emodepside/kg body weight (group 1), 0.25 mg emodepside/kg body weight (group 2) and 0.1 mg emodepside/kg body weight (group 3), respectively. In the second study, 10 eight-weeks-old kittens were inoculated with 350 L3 larvae of A. tubaeforme. Four weeks after infection, the kittens were allocated to two treatment groups and were treated with 0.1 mg emodepside/kg body weight (group 1) or 0.25 mg emodepside/kg body weight (group 2). In both studies, all kittens received a reference treatment with Drontal(®) (230 mg pyrantel embonate and 20 mg praziquantel per tablet) at the recommended dose of one tablet/4 kg body weight 5 days after treatment with Procox(®). Anthelmintic efficacy was calculated by reduction in worm numbers expelled with the faeces following treatment with Procox(®) as compared with faecal worm numbers after reference treatment with Drontal(®), by thus avoiding necropsy of the animals.In the T. cati study, emodepside was at 99.9 %, 100 % and 96.5 % effective at a dosage of 0.5 mg, 0.25 mg and 0.1 mg per kg body weight, respectively. Against A. tubaeforme emodepside was at 95.7 % and 100 % effective at a dosage of 0.1 mg and 0.25 mg per kg body weight. No adverse events were seen during either study.It can be concluded that Procox(®) is efficacious for the control of mature adult T. cati and A. tubaeforme infections in cats at a single-dose rate of 0.25 mg emodepside/kg body weight.

Efficacy of emodepside plus praziquantel tablets (Profender tablets for dogs) against mature and immature adult Ancylostoma caninum and Uncinaria stenocephala infections in dogs.

This paper reports the efficacy of a novel flavoured tablet formulation of emodepside plus praziquantel (Profender tablets for dogs) against mature and immature adult hookworms (Ancylostoma caninum and Uncinaria stenocephala) in dogs. The tablets were used at the minimum recommended dose of 1 mg emodepside and 5 mg praziquantel per kg body weight. Four randomised, blinded and controlled laboratory studies demonstrated >95% efficacy against mature and immature adult stages of U. stenocephala and four randomised, blinded and controlled laboratory studies demonstrated >98% efficacy against mature and immature adult stages of A. caninum. No side effects of the treatment were observed. It is concluded that the emodepside plus praziquantel tablet is an effective and safe treatment against mature and immature hookworms.

Efficacy of emodepside plus praziquantel tablets (Profender tablets for dogs) against mature and immature infections with Toxocara canis and Toxascaris leonina in dogs.

The efficacy of emodepside plus praziquantel tablets (Profender tablets for dogs) against mature adult, immature adult and larval stages of Toxocara canis and Toxascaris leonina was evaluated in ten randomised, blinded and placebo-controlled dose confirmation studies in naturally or experimentally infected dogs. The tablets were used at the proposed minimum dose of 1 mg emodepside and 5 mg praziquantel per kg body weight. Efficacy was calculated based on worm counts after necropsy. Five studies demonstrated >99% efficacy against mature adult, >92% efficacy against immature adult, >98% efficacy against L4 and >94% efficacy against L3 larval stages of T. canis. Another five studies demonstrated >99% efficacy against mature and immature adult and >95% efficacy against L4 larval stages of T. leonina. No side effects of the treatment were observed. Emodepside plus praziquantel tablets thus provide a comprehensive new treatment option for ascarid infections in the dog.

Efficacy of emodepside plus praziquantel tablets (Profender tablets for dogs) against mature and immature adult Trichuris vulpis infections in dogs.

This paper reports on the efficacy of a novel flavoured tablet formulation of emodepside plus praziquantel (Profender tablets for dogs) against mature and immature adult whipworms (Trichuris vulpis) at the proposed minimum dose of 1 mg emodepside and 5 mg praziquantel per kg body weight in dogs. Three randomised, blinded and controlled laboratory studies with naturally or experimentally infected dogs were performed. The first study was conducted as a dose determination study in experimentally infected dogs using three different dose levels, i.e., 0.5x, 1x and 2x the minimum therapeutic dose. Two further studies confirmed the efficacy of emodepside plus praziquantel tablets against mature and immature adult T. vulpis at the recommended minimum dose. In all three studies, the efficacy against mature and immature adult T. vulpis was >99%. No side effects of the treatment were observed. It is concluded that the emodepside plus praziquantel tablet is an effective and safe treatment against mature and immature adult stages of T. vulpis in dogs.

Efficacy of emodepside plus praziquantel tablets (Profender tablets for dogs) against mature and immature cestode infections in dogs.

The efficacy of a novel flavoured tablet formulation of emodepside plus praziquantel (Profender tablets for dogs) against intestinal cestodes was investigated in four randomised, blinded placebo-controlled dose confirmation studies in dogs experimentally infected with Echinococcus granulosus or E. multilocularis and in dogs naturally infected with Dipylidium caninum or Taenia spp. The tablets were used at the minimum recommended dose of 1 mg emodepside and 5 mg praziquantel per kg body weight. The studies demonstrated 100% efficacy against mature and immature E. granulosus and E. multilocularis and mature Taenia spp. and D. caninum. Additionally, one of the studies demonstrated non-interference of emodepside with the efficacy of praziquantel against D. caninum. No side effects of the treatment were observed. It is concluded that emodepside plus praziquantel tablets are safe and effective against mature and immature stages of E. granulosus and E. multilocularis and mature stages of Taenia spp. and D. caninum.

Field evaluation of the efficacy and safety of emodepside plus praziquantel tablets (Profender tablets for dogs) against naturally acquired nematode and cestode infections in dogs.

A controlled, blinded and randomised multicentre field study evaluated the efficacy and safety of a new anthelmintic tablet formulation containing emodepside plus praziquantel (Profender tablets for dogs) in the treatment of gastrointestinal nematode and cestode infections in dogs in France, Germany, Portugal and Slovakia. Dogs positive for nematodes and/or cestodes (demonstrated by faecal egg counts and/or the presence of proglottids) were treated with emodepside plus praziquantel tablets (n = 239) or the reference product containing milbemycin oxime and praziquantel (Milbemax [n = 115]) at the recommended dose rate. Two faecal samples collected between 7 and 13 days after treatment were evaluated for proglottids, nematode and cestode eggs. No suspected adverse drug reactions were observed in the study. The following parasite species were identified: Trichuris vulpis, Toxocara canis, Toxascaris leonina, Uncinaria stenocephala, Ancylostoma caninum, Dipylidium caninum, Taeniidae and Mesocestoides spp. Geometric mean nematode egg counts in dogs treated with emodepside plus praziquantel tablets were reduced by 99.9 % compared with a reduction of 99.6 % for the reference product. Statistical analysis demonstrated noninferiority of investigational versus reference product (p = 0.0342). None of the dogs treated with emodepside plus praziquantel or reference product remained positive for cestodes after treatment. The study demonstrated that emodepside plus praziquantel tablets are safe and highly efficacious against a broad spectrum of nematodes and cestodes under field conditions.

Comparative efficacy and safety of two treatment regimens with a topically applied combination of imidacloprid and moxidectin (Advocate) against generalised demodicosis in dogs.

This laboratory study compared the efficacy of two treatment regimens using an imidacloprid (10%)/moxidectin (2.5%) topical formulation (Advocate, Bayer) on dogs with generalised demodicosis. Sixteen dogs were randomly allocated to two equal groups. One group was treated at 28-day intervals for 12 weeks and the second group at weekly intervals for 15 weeks. Mite numbers were estimated and demodectic lesions were evaluated on each dog before treatment and at approximately 28-day intervals thereafter. Consistently greater reduction in mite numbers was recorded for the weekly treatment regimen. Dogs treated at weekly intervals exhibited markedly fewer clinical signs and greater hair regrowth and weight gain than those treated at 28-day intervals. To assess the safety of a weekly treatment interval in dogs, a study was done in which the investigational compound was administered at weekly intervals at five times the recommended dose for a period of 16 consecutive weeks. Apart from transient erythema at the site of administration in one dog and scaliness of the skin in another, no clinical signs of toxicity could be observed. Assessment of 27 blood parameters indicated that only basophils were outside the reference values on days +13 and +69, during the safety trial period.