In vitro insecticidal effects of fipronil and beta-cyfluthrin on larvae of the blowfly Lucilia sericata

The insecticidal effects of the phenylpyrazole, fipronil, and a pyrethroid, beta-cyfluthrin, on larvae of the blowfly Lucilia sericata were determined in laboratory assays. When first stage larvae of L. sericata were reared on homogenized pig liver which had been treated with known amounts of test compounds, both fipronil and beta-cyfluthrin induced significant levels of mortality compared to acetone and water controls. However, fipronil was approximately 10 times more toxic than beta-cyfluthrin to L. sericata larvae following ingestion. Beta-cyfluthrin had little effect on mortality until concentrations of approximately 0.5 ppm were reached. In contrast, fipronil effected L. sericata mortality at a concentration of 0.05 ppm and 100% mortality was reached by 0.5 ppm. The lethal concentration (LC50) value for beta-cyfluthrin was 1.56 ppm as compared to 0.14 ppm for fipronil. Following contact of first and third stage larvae with cloth impregnated with known amounts of test compound, the mortality profiles of fipronil and beta-cyfluthrin were similar. At short contact times, the LC50 values for fipronil were lower than those for beta-cyfluthrin. However, at the highest contact time evaluated for the first stage larvae, 300 s, there was a reversal in this trend. The results suggest that the phenylpyrazole fipronil may represent a new potential insecticide for development against blowfly strike of sheep.     

Liver biopsy techniques for adult horses and neonatal foals to assess copper status

Objective To evaluate standing, percutaneous, ultrasound-guided, transthoracic liver biopsy in mares, and transabdominal, laparoscopically-guided, liver biopsy under general anaesthesia in foals, as techniques for obtaining tissue for assessment of copper status. The techniques were evaluated with respect to ease of use and effect on the animal.
Procedure Twenty of 24 Thoroughbred mares and 21 of their foals were biopsied. The animals were part of a larger study of the effect of copper supplementation on copper status and the prevalence of developmental orthopaedic disease. Livers were also collected from unrelated horses and sampled to investigate the variability in the distribution of copper in liver tissue.
Result The biopsy technique caused no lasting effect on the mares, but there was an increased risk of viscus penetration associated with taking multiple biopsy cores. The use of ultrasonography to scan the target area for the liver identified four cases that were not appropriate candidates for liver biopsy, because of large intestine being located in the biopsy area. In the foals there were no serious postoperative adverse effects, nor was there any evidence of problems caused by the procedure when the abdomen was examined post-mortem at 5 months of age. In livers collected to investigate the variability of copper concentration, copper appeared to be relatively evenly distributed through the liver.
Conclusion Standing, percutaneous, ultrasound-guided, transthoracic liver biopsy in mares, and transabdominal, laparoscopically-guided, liver biopsy under general anaesthesia in foals are convenient procedures for obtaining liver tissue for assessing copper status in horses. The use of ultrasound to identify liver tissue is recommended, especially in older mares.     

Experimental infection of N'Dama cattle with trypanosomes usingGlossina palpalis gambiensis caught in the wild

Summary The transmissibility of trypanosome infection to N'Dama cattle by tsetse flies caught in the field was examined. Wild-caughtGlossina palpalis gambiensis were transferred singly into small numbered cages and allowed to feed on 14 uninfected N'Dama cattle. Following a completed feed the tsetse were dissected and infection in the proboscis, the salivary glands and the gut was recorded. Each animal was bitten by a number of tsetse ranging from five up to 64 flies. Following dissection of the tsetse flies, seven of the cattle were found to have been bitten by a single infected tsetse, five by two, while the remaining two were each fed upon by three infected tsetse. The tsetse were harbouring eitherTrypanosoma vivax or a trypanosome species belonging to theNannomonas subgenus or both species. The experimental animals were monitored daily over a period of three months for the appearance of trypanosomes in the blood and for antibodies in their sera. Other parameters such as body temperature, local skin reactions, packed red cell volume and weight changes were also measured. Trypanosomes were first detected eight days after the infective bite. Only five of the 14 cattle became infected, of which three had been exposed to a single infected tsetse fly.Trypanosoma vivax was detected in one animal,Trypanosoma congolense in two cattle and mixed infections of both species in the remaining two animals. These findings show that N'Dama cattle can become infected with trypanosomes through the bite of a single infected tsetse fly under field conditions. However, only five (possibly eight) of the 23 infected tsetse were able to transmit the parasites successfully.

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Infeccion Experimental De Ganado N'Dama Con Tripanosomas UsandoGlossina Palpalis Gambiensis Atrapadas En El Campo

Resumen Se estudió la transmisibilidad de infecciones con tripanosomas a ganado N'Dama, a través de moscas tsetse atrapadas en el campo. LasGlossina palpalis gambiensis atrapadas, fueron transferidas individualmente a jaulas numeradas, donde se alimentaron sobre 14 animales N'Dama sin infección alguna.Una vez completada una comida, las moscas se disecaron buscándose infecciones en la proboscis, glándulas salivares e intestino. Cada animal fue picado por un buen número de moscas, en un rango de cinco a 64. Seguida a la disección de las moscas tsetse, siete bovinos fueron picados por una sola mosca infectada; cinco por dos, mientras que los otros dos fueron cada uno picado por tres tsetse infectadas. Las moscas estaban infectadas conTrypanosoma vivax o con especies de tripanosomas pertenecientes al subgéneroNannomonas, o por ambas especies.Los animales fueron seguidos clínicamente día a día por un período de tres meses por la presencia de tripanosomas en la sangre y anticuerpos en el suero. Se tomaron en cuenta otros parámetros como la temperatura corporal, reacciones cutáneas locales, volumen corpuscular celular y peso corporal. Los primeros tripanosomas se detectaron ocho días después de la picadura de moscas infectadas. Solamente cinco de los 14 bovinos se infectaron, de los cuales tres, habían sido expuestos a una única tsetse infectada. Se detectóTrypanosoma vivax en un animal,T. congolense en dos bovinos más e infecciones mixtas en los otros dos.Estos hallazgos demuestran, que el ganado N'Dama puede infectarse con tripanosomiasis, seguidamente de la picadura de una sola tsetse infectada bajo condiciones de campo. Sin embargo, solamente cinco (posiblemente ocho) de las 23 tsetse infectadas, fueron capaces de transmitir el parásito exitosamente.

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Infection Experimentale De Bovins N'Dama Avec Des Trypanosomes A l'Aide DeGlossina Palpalis Gambiensis Capturees A l'Etat Sauvage

Résumé La transmissibilité de possibilité de transmission de la trypanosomose à des bovins N'Dama par des mouches tsé-tsé capturées sur le terrain a été examinée. DesGlossina palpalis gambiensis capturées à l'état sauvage ont été transférées individuellement dans de petities cages numérotées et placées pour se nourrir sur 14 bovins N'Dama indemnes.A la suite d'un repas complet, les mouches ont été disséquées et on a enregistré l'infection dans le proboscis, les glandes salivaires et l'intestin. Chaque animal a été piqué par un nombre de mouches allant de cinq à soixante quatre. A la suite de la dissection des glossines, on a trouvé que sept bovins avaient été piqués par une seule mouche infectée, cinq par deux mouches, alors que les deux derniers avaient servi à nourrir chacun trois glossines infectées. Les mouches tsé-tsé hébergeaient soitTrypanosoma vivax ou une espèce de trypanosomes appartenant au sous genreNannomonas ou par les deux espèces.Les animaux d'expérience ont été suivis quotidiennement pendant trois mois pour observer l'apparition des trypanosomes dans le sang et des anticorps dans leur sérum. D'autre paramètres tels que la température corporelle, les réactions cutanées locales, le volume erythrocytaire et les variations pondérales ont également été mesurés. Les trypanosomes ont été détectés pour la première fois huit jours après la morsure infectante. Seuls cinq des 14 bovins se sont infectés, parmi lesquels trois avaient été exposés à une seule mouche infectée. On a détéctéTrypanosoma vivax chez un animal,T. congolense chez deux bovins et des infections mixtes des deux espèces chez les deux derniers animaux infectés. Ces observations montrent que les bovins N'Dama peuvent devenir infectés par des trypanosomes par la piqure d'une unique mouche tsé-tsé infectée dans les conditions du terrain. Cependant, seulement cinq (peut-être huit) des 23 glosssines infectées ont été capables de transmettre les parasites avec succès.

     

Naphthalophos combinations with benzimidazoles or levamisole as effective anthelmintics for sheep

Objective: To investigate the relative efficacy and safety of the anthelmintic naphthalophos in sheep, either given alone or in combination with benzimidazole (fenbendazole and albendazole) or levamisole anthelmintics.
Design: A parasitological study using faecal egg count reduction tests, a validating slaughter trial and field safety trials.
Procedure: Faecal egg count reduction tests were carried out on 13 farms. Naphthalophos and combinations of naphthalophos with levamisole and fenbendazole were included in the drench tests. On one property a controlled efficacy study was carried out to validate faecal egg count reduction test findings. In this trial, sheep were slaughtered 10 days after treatment and the remaining parasites recovered from the gastro-intestinal tract. Safety trials were carried out on eight farms where approximately 50 000 sheep were treated with naphthalophos and albendazole that were tank mixed in the backpack.
Results: The efficacy of naphthalophos alone in faecal egg count reduction tests ranged from 59 to 98% with one test showing 95% reduction. The efficacy of naphthalophos and levamisole ranged from 74 to 100%, with 5 farms showing 95% reduction. The efficacy of naphthalophos and fenbendazole ranged between 88 and 100% with 95% reduction achieved on 10 farms. The controlled efficacy study showed a good correlation between the faecal egg count reduction tests and numbers of parasites recovered, except for Nematodirus where the faecal egg count reduction tests overestimated efficacy. The mortality rate in the safety trials was 0.05%, with most fatalities occurring on one farm.
Conclusion: The combination of naphthalophos and fenbendazole was more effective than a combination of naphthalophos and levamisole, and will provide a sufficiently safe drench rotation option.