A field study on the efficacy of ivermectin via subcutaneous route against chewing lice (Bovicola caprae) infestation in naturally infested goats.

Caprine pediculosis is an ectoparasitic disease of great concern among goat farmers in India. It may be caused by either sucking lice or chewing lice; the latter one results in severe skin lesions, leading to production loss. This study evaluated the effectiveness of the macrocytic lactone drug, ivermectin, administered via subcutaneous injection, against chewing lice Bovicola (Damalinia) caprae infestation in naturally infested goats. The study was conducted on 20 goats with severe B. caprae infestation. Animals of group A (n = 10) were treated using a single dose of ivermectin (200 µg/kg body weight) subcutaneously and animals of group B (n = 10) underwent placebo therapy using normal saline. The animals were examined on days 0, 3, 7, 14, 21, 28, 42 and 56 for lice counts. There was 100% elimination of lice in all animals of group A and effective protection from re-infection remained at least for 21 days. Considerable improvement in haematological parameters was also observed by day 21. Based on this study, ivermectin injected via a subcutaneous route can be used effectively for the therapeutic and prophylactic management of chewing lice infestation in goats maintained under an extensive grazing system.

Control of biting lice, Mallophaga - a review.

The chewing lice (Mallophaga) are common parasites of different animals. Most of them infest terrestrial and marine birds, including pigeons, doves, swans, cormorants and penguins. Mallophaga have not been found on marine mammals but only on terrestrial ones, including livestock and pets. Their bites damage cattle, sheep, goats, horses and poultry, causing itch and scratch and arousing phthiriasis and dermatitis. Notably, Mallophaga can vector important parasites, such as the filarial heartworm Sarconema eurycerca. Livestock losses due to chewing lice are often underestimated, maybe because farmers notice the presence of the biting lice only when the infestation is too high. In this review, we examined current knowledge on the various strategies available for Mallophaga control. The effective management of their populations has been obtained through the employ of several synthetic insecticides. However, pesticide overuse led to serious concerns for human health and the environment. Natural enemies of Mallophaga are scarcely studied. Their biological control with predators and parasites has not been explored yet. However, the entomopathogenic fungus Metarhizium anisopliae has been reported as effective in vitro and in vivo experiments against Damalinia bovis infestation on cattle. Furthermore, different Bacillus thuringiensis preparations have been tested against Mallophaga, the most effective were B. thuringiensis var. kurstaki, kenyae and morrisoni. Lastly, plant-borne insecticides have been evaluated against Mallophaga. Tested products mainly contained bioactive principles from two Meliaceae, Azadirachta indica, and Carapa guianensis. High efficacy of neem-borne preparations was reported, leading to the development of several products currently marketed. Overall, our review highlighted that our knowledge about Mallophaga vector activity and control is extremely patchy. Their control still relied on the employ of chemical pesticides widely used to fight other primary pests and vectors of livestock, such as ticks, while the development of eco-friendly control tool is scarce. Behavior-based control of Mallophaga, using pheromone-based lures or even the Sterile Insect Technique (SIT) may also represent a potential route for their control, but our limited knowledge on their behavioral ecology and chemical communication strongly limit any possible approach.

Essential oils in the management of the donkey louse, Bovicola ocellatus.

REASONS FOR PERFORMING STUDY: Chewing lice are widespread and clinically compromising parasites of livestock and equids. Their management is complicated by growing levels of resistance to commonly applied insecticides. Hence, the development of novel approaches to their control is of major clinical interest. OBJECTIVES: To assess the effects of incorporating the essential oils of tea tree and lavender into a grooming programme for populations of donkeys with natural infestations of Bovicola ocellatus in the UK and Ireland when louse populations were at their winter seasonal peak. STUDY DESIGN: In vivo field trial. METHODS: Suspensions of 5% (v/v) tea tree or lavender oil or an excipient only control were groomed into the coats of winter-housed donkeys (n = 198) on 2 occasions, 2 weeks apart. Louse counts were conducted before each application and 2 weeks later. RESULTS: After 2 applications, the groups groomed with lavender or tea tree oil suspensions had a significant reduction in louse intensity, with a mean decline in louse abundance of 78% (95% confidence interval 76-80%). Louse numbers in the groups groomed with excipient only either did not change or increased significantly. Donkey hair length had no effect on the decline in louse numbers. CONCLUSIONS: These results demonstrate that the inclusion of essential oil suspensions during grooming can be used to manage louse populations successfully.

Dipping and jetting with tea tree (Melaleuca alternifolia) oil formulations control lice (Bovicola ovis) on sheep.

The in vivo pediculicidal effectiveness of 1% and 2% formulations of tea tree (Melaleuca alternifolia) oil (TTO) against sheep chewing lice (Bovicola ovis) was tested in two pen studies. Immersion dipping of sheep shorn two weeks before treatment in both 1% and 2% formulations reduced lice to non detectable levels. No lice were found on any of the treated sheep despite careful inspection of at least 40 fleece partings per animal at 2, 6, 12 and 20 weeks after treatment. In the untreated sheep louse numbers increased from a mean (± SE) of 2.4 (± 0.7) per 10 cm fleece part at 2 weeks to 12.3 (± 4.2) per part at 20 weeks. Treatment of sheep with 6 months wool by jetting (high pressure spraying into the fleece) reduced louse numbers by 94% in comparison to controls at two weeks after treatment with both 1% and 2% TTO formulations. At 6 and 12 weeks after treatment reductions were 94% and 91% respectively with the 1% formulation and 78% and 84% respectively with the 2% formulation. TTO treatment also appeared to reduce wool damage in infested sheep. Laboratory studies indicated that tea tree oil 'stripped' from solution with a progressive reduction in concentration as well as volume as more wool was dipped, indicating that reinforcement of active ingredient would be required to maintain effectiveness when large numbers of sheep are treated. The results of these studies suggest significant potential for the development of ovine lousicides incorporating TTO.

Pyrethroid tolerance in the chewing louse Bovicola (Werneckiella) ocellatus.

Equine pediculosis is a significant health and welfare issue, particularly in elderly and chronically debilitated animals. Currently infestation is controlled predominantly using topically applied pyrethroid insecticides, allowing limited scope for the rotation of drugs and increasing the risk of selection for resistance. Here the insecticidal efficacies of two pyrethroid-based products against the louse Bovicola (Werneckiella) ocellatus collected from donkeys were examined in vitro. The products were cypermethrin (Deosect™, Pfizer Ltd., 5% (w/v) cypermethrin, cutaneous spray) and permethrin (Switch™, VetPlus Ltd., 4% (w/v) permethrin, pour-on). The pyrethroid efficacy was contrasted with that of the organophosphate diazinon, since the louse populations examined were unlikely to have had prior exposure to this compound. The efficacy of diluted pure permethrin, the excipient, butyl dioxitol and the synergist piperonyl butoxide in the presence of the pyrethroids, were also considered. At the concentrations recommended for animal application, neither 4% (w/v) permethrin, nor 0.1% (w/v) cypermethrin had any significant effect on the mortality of B. ocellatus and neither induced significantly more mortality than an acetone-only control. In contrast, 0.04% diazinon caused 70% mortality within 4h and 100% mortality after 24h exposure. The addition of a potential pyrethroid synergist, piperonyl butoxide, in combination with cypermethrin and permethrin, resulted in no significant increase in mortality. It is concluded that the population of lice tested display a high level of pyrethroid tolerance which is likely to reflect the development of resistance. Twenty-four hours after routine treatment of 10 donkeys with a pour-on permethrin product (Switch™, VetPlus Ltd., 4% (w/v) permethrin, pour-on) hair tufts taken from their flanks were not significantly insecticidal compared with hair from the midline application site, implying a low level of insecticide distribution. Such a distribution pattern is likely to create an insecticide concentration gradient over the body and further facilitate selection for resistance.

Bioactivity of tea tree oil from Melaleuca alternifolia against sheep lice (Bovicola ovis Schrank) in vitro.

Tea tree oil (TTO) from the Australian native plant Melaleuca alternifolia has wide ranging bio-active properties, including insecticidal and repellent activity against arthropods. Furthermore, composition of commercially available Australian TTO is specified under an International Organization for Standardization standard (ISO 4730), reducing the potential for variable effects often noted with botanical pesticides. The effect of TTO, meeting the ISO standard for terpinen-4-ol chemotype, was tested against sheep lice (Bovicola ovis Schrank) in a series of laboratory studies. Immersion of wool for 60s in formulations containing concentrations of 1% TTO and above caused 100% mortality of adult lice and eggs. Exposure to vapours from TTO, delivered as droplets in fumigation chambers and when applied to wool also caused high mortality in both lice and eggs. The main active component of TTO in the fumigant tests was terpinen-4-ol. Treated surface assays and tests with wool where the formulation was allowed to dry before exposure of lice indicated low persistence. These studies demonstrate that TTO is highly toxic to sheep lice and active at concentrations that suggest potential for the development of TTO-based ovine lousicides.

Unstable pyrethroid resistance in sheep body lice Bovicola ovis (Schrank), (Phthiraptera: Trichodectidae) and its implications for lice control on sheep.

A retrospective study in which the 18 years treatment history of a mob of sheep hosting a pyrethroid resistant strain of sheep body lice was compared with the coincidental changes in that strain's response to cypermethrin, provided a unique opportunity to investigate the stability of pyrethroid resistance in this species. Resistance levels remained very high (resistance factors (RF)=75-145) for at least five years following the cessation of pyrethroid treatments but within ten years had dropped to only 5, a level similar to many normal field strains and certainly not indicative of high-level resistance. Resumption of pyrethroid treatment of sheep infested with these lice caused a coincidental increase in resistance to an extreme level (RF=321) within two years. Wool producers considering a return to pyrethroid use to control louse infestations should be aware that such a strategy may not be sustainable in the long term and that in Australia effective registered alternative treatments are available.

Evaluation of Catharanthus roseus leaf extract-mediated biosynthesis of titanium dioxide nanoparticles against Hippobosca maculata and Bovicola ovis.

The purpose of the present study was based on assessments of the antiparasitic activities of synthesized titanium dioxide nanoparticles (TiO(2) NPs) utilizing leaf aqueous extract of Catharanthus roseus against the adults of hematophagous fly, Hippobosca maculata Leach (Diptera: Hippoboscidae), and sheep-biting louse, Bovicola ovis Schrank (Phthiraptera: Trichodectidae). The synthesized TiO(2) NPs were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The formation of the TiO(2) NPs synthesized from the XRD spectrum compared with the standard confirmed spectrum of titanium particles formed in the present experiments were in the form of nanocrystals, as evidenced by the peaks at 2θ values of 27.43°, 36.03°, and 54.32°. The FTIR spectra of TiO(2) NPs exhibited prominent peaks at 714 (Ti-O-O bond), 1,076 (C-N stretch aliphatic amines), 1,172 (C-O stretching vibrations in alcoholic groups), 1,642 (N-H bend bond), and 3,426 (O-H stretching due to alcoholic group). SEM analysis of the synthesized TiO(2) NPs clearly showed the clustered and irregular shapes, mostly aggregated and having the size of 25-110 nm. By Bragg's law and Scherrer's constant, it is proved that the mean size of synthesized TiO(2) NPs was 65 nm. The AFM obviously depicts the formation of the rutile and anatase forms in the TiO(2) NPs and also, the surface morphology of the particles is uneven due to the presence of some of the aggregates and individual particles. Adulticidal parasitic activity was observed in varying concentrations of aqueous leaf extract of C. roseus, TiO(2) solution, and synthesized TiO(2) NPs for 24 h. The maximum parasitic activity was observed in aqueous crude leaf extracts of C. roseus against the adults of H. maculata and B. ovis with LD(50) values of 36.17 and 30.35 mg/L, and r (2) values of 0.948 and 0.908, respectively. The highest efficacy was reported in 5 mM TiO(2) solution against H. maculata and B. ovis (LD(50) = 33.40 and 34.74 mg/L; r (2) = 0.786 and 0.873), respectively, and the maximum activity was observed in the synthesized TiO(2) NPs against H. maculata and B. ovis with LD(50) values of LD(50) = 7.09 and 6.56 mg/L, and r (2) values of 0.880 and 0.913, respectively. This method is considered as an innovative alternative approach to control the hematophagous fly and sheep-biting louse.

Toxicity of essential and non-essential oils against the chewing louse, Bovicola (Werneckiella) ocellatus.

The toxicity of six plant essential oils to the chewing louse, Bovicola (Werneckiella) ocellatus collected from donkeys, was examined in laboratory bioassays. The oils examined were: tea-tree (Melaleuca alternifolia), lavender (Lavandula angustifolia), peppermint (Mentha piperita), eucalyptus (Eucalyptus globulus Labillardiere), clove bud (Eugenia caryophyllata) and camphor (Cinnamomum camphora). All except camphor oil showed high levels of toxicity, with significant dose-dependent mortality and an LC(50) at concentrations of below 2% (v/v). Hundred percent mortality was achieved at concentrations of 5-10% (v/v). Two essential oil components: eugenol and (+)-terpinen-4-ol showed similar levels of toxicity. The data suggest that these botanical products may offer environmentally and toxicologically safe, alternative veterinary pediculicides for the control of ectoparasitic lice.

Effects of a neem seed extract (MiteStop®) on mallophages (featherlings) of chicken: in vivo and in vitro studies.

Mallophages of birds (featherlings) are mostly very tiny and can even as adults better be recognized by their movements than by their elongate body shape when using just the naked eye. Since some species (e.g., the "shaft louse" Menopon gallinae, the elongate feather louse Lipeurus caponis, or Columbicola sp.) may pierce the pulp of feathers or the skin by their biting or scratching mandibles and thus lick the excreted blood, they may be extremely dangerous especially to young birds, even if they only feed by nibbling along the feather surface and/or eat epidermal debris. The present paper reports on the successful treatment of different races of fowls being severely infested with both above cited species. This in vivo treatment was done either by a short dipping of the whole fowl into the 1:33 dilution (with tap water) of a neem seed extract (MiteStop®) or by spraying them with the freshly diluted product. It was seen that the dead mallophages dropped down from the feathers as soon as they were dry again. As a precaution, a second treatment was done by some owners 1 week after the first one in order to eliminate all stages, which eventually might have hatched from untouched nits during the time interval between the two treatments. When controlling the treated fowls 4 weeks after the treatment, in no case (treated once or twice), living motile stages were diagnosed indicating the high efficacy of this nontoxic neem seed extract. When treating in vitro cutoff feathers contaminated with L. caponis, it was seen under the stereomicroscope, that the mallophages tried to run away from the 1:33 water-diluted active compound indicating that there is also a repellent effect. Treated L. caponis stopped leg movements within 3 min and died on their feathers within 1-20 min. Then, the last slight trembling movements of their legs and convulsions of their intestine stopped finally.

Lousicidal activity of synthesized silver nanoparticles using Lawsonia inermis leaf aqueous extract against Pediculus humanus capitis and Bovicola ovis.

In the present work, we describe inexpensive, nontoxic, unreported and simple procedure for synthesis of silver nanoparticles (Ag NPs) using leaf aqueous extract of Lawsonia inermis as eco-friendly reducing and capping agent. The aim of the present study was to assess the lousicidal activity of synthesized Ag NPs against human head louse, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae), and sheep body louse, Bovicola ovis Schrank (Phthiraptera: Trichodectidae). Direct contact method was conducted to determine the potential of pediculocidal activity and impregnated method was used with slight modifications to improve practicality and efficiency of tested materials of synthesized Ag NPs against B. ovis. The synthesized Ag NPs characterized with the UV showing peak at 426 nm. X-ray diffraction (XRD) spectra clearly shows that the diffraction peaks in the pattern indexed as the silver with lattice constants. XRD analysis showed intense peaks at 2θ values of 38.34°, 44.59°, 65.04°, and 77.77° corresponding to (111), (200), (220), and (311) Bragg's reflection based on the fcc structure of Ag NPs. Fourier transform infrared spectroscopy (FTIR) spectra of Ag NPs exhibited prominent peaks at 3,422.13, 2,924.12, 2,851.76, 1,631.41, 1,381.60, 1,087.11, and 789.55 cm(-1). Scanning electron microscopy (SEM) micrograph showed mean size of 59.52 nm and aggregates of spherical shape Ag NPs. Energy dispersive X-ray spectroscopy (EDX) showed the complete chemical composition of the synthesized Ag NPs. In pediculocidal activity, the results showed that the optimal times for measuring percent mortality effects of synthesized Ag NPs were 26, 61, 84, and 100 at 5, 10, 15, and 20 min, respectively. The average percent mortality for synthesized Ag NPs was 33, 84, 91, and 100 at 10, 15, 20, and 35 min, respectively against B. ovis. The maximum activity was observed in the aqueous leaf extract of L. inermis, 1 mM AgNO(3) solution, and synthesized Ag NPs against P. humanus capitis with LC(50) values of 18.26, 7.77, and 1.33 mg l(-1) and r (2) values of 0.863, 0.900, and 0.803 and against B. ovis showed with LC(50) values of 21.19, 8.49, and 1.41 mg l(-1) and r (2) values of 0.920, 0.938 and 0.870, respectively. The findings revealed that synthesized Ag NPs possess excellent anti-lousicidal activity.