Protection of pastured cattle from black flies (Diptera: Simuliidae): Improved weight gains following a dermal application of phosmet

In two experiments, a pour-on application of phosmet at 25 mg kg^?1 reduced the harassment of cattle by black flies for up to 5–6 weeks posttreatment. During this period, the treated groups either gained more weight or loss less weight than their controls. The untreated groups made compensatory gains when teh black fly activity decreased or ceased. No significant differences existed between the average daily gains of a treated group and its control either for the posttreatment-periods of 9 and 15 weeks or for the experimental periods of 15 and 20 weeks in the two experiments.Black fly toxemia was not seen in indigenous cattle or in naive steers brought into a black fly infested area 1–2 weeks before the onset of black fly activity.     

Review of blackfly (Diptera: Simuliidae) control in South Africa

The medical, veterinary and economic importance of blackflies in South Africa, and the historical development of blackfly control programmes in various South African rivers, are reviewed in this paper. In 1996 it was estimated that blackflies can cause more than R 88 million damages per annum along the middle and lower Orange River where Simulium chutteri is considered the main pest species. A clear link between the construction of dams and the spread of the blackfly problem was shown. Four phases characterize the development of blackfly control in South Africa: (1) during the 1960s blackflies in the Vaal River were controlled with DDT; (2), during the 1970s and into the 1980s blackflies were controlled using water-flow manipulation; (3) when used at strategic times, water-flow manipulation could be used to enhance the effect of natural predator populations; and (4) during the 1990s the organophosphate temephos and toxins produced by the bacterium Bacillus thuringiensis var. israelensis were tested for their efficacy against blackflies. The larvicides temephos and B. thuringiensis proved to be effective and are still used in several control programmes. The latest research focuses on the factors that influence adult blackfly survival and annoyance, as well as the development of methods that can be used to protect sheep from blackfly attacks.     

Variation in population density of horn flies (Haematobia irritans irritans) (L.) (Diptera: Muscidae) in Nellore cattle (Bos indicus)

The population density of horn flies was evaluated in the year 1998 in the municipality of Ara?atuba, S?o Paulo Brazil, in relation to temperature and rainfall conditions. Two lots of 30 Nellore steers (Bos indicus) were used which had no insecticidal treatment and were naturally infested with horn flies. The infestations were assessed by two counting methods, i.e., the traditional estimate method and the filming method. The highest fly frequencies were recorded in spring, summer, autumn and the lowest frequencies were recorded in winter. The increase in fly number was positively correlated (P<0.05) with rainfall.     

Validation of a subjective counting method for a horn flies (Haematobia irritans irritans) (Diptera: Muscidae) population in a cattle herd

A trained observer direct count method to measure horn fly population was evaluated to determine the reliability (inter-observer agreement) and its validity when compared with a "gold standard" method (video film). All the counts were performed with the animals restrained in a chute in a single herd. A direct count of horn flies by each of two observers on opposite sides of the animal was made. In addition a videotape recording of the counting surface on each animal was made. Horn flies were counted on 80 cows in the morning twice monthly from 22 October 1999 to 24 March 2000. The correlation between observer counts was high as was the correlation between observer counts and counts made from a videotape recording. Direct counts by trained observers were highly reliable and had good validity. However, videotape recording can be useful when the horn fly population is high, because it is faster in the field than the direct count method. The results of this study suggest that the direct count method can be used with confidence under field conditions.     

疑似碘酊致牛死亡一例

笔者在临床上曾遇到一疑似“碘酊”致牛死亡的病例,由于未曾见过碘酊致牛死亡的报道,查阅资料也终未得到答案.笔者将其整理如下,供同行探讨。     

A survey of annoyance of livestock by Simulium chutteri Lewis along the Orange River, South Africa (Diptera: Simuliidae)

A survey by means of questionnaires was conducted along the Orange River to determine the extent of blackfly annoyance to livestock during 1984-1988. Severe annoyance reached peaks during September-November and increased over the years. Annoyance levels decreased with distance from the river with occasional severe annoyance as far away as 76 km. Annoyance levels increased with distance downstream from the P. K. le Roux dam to Augrabies (750 km). Greater water releases for increased irrigation and electricity generation may be an important reason for the higher annoyance levels. Present day high and increasing irrigation water requirements and the great length of the river probably render control by water level fluctuations impractical. Loss of condition of especially small livestock is the main consequence of annoyance by female blackflies. Decreased percentage lambing and occasional deaths were also reported.     

Development of treated targets for controlling stable flies (Diptera: Muscidae)

Electrocution techniques were used to determine if treated targets similar to those used for tsetse control could be developed for stable fly control. In a series of two experiments, a half blue and half black (UK) 1 m2 target constructed of trigger cotton poplin was determined to be acceptable for development studies. In the first experiment, an average of 350 stable flies per hour (maximum 794 flies in 1 h) was collected using the UK target. A time-delayed circuit trial using untreated UK targets demonstrated that stable flies remained on or around the targets for at least 30 s. Two experiments were conducted with time-delayed circuits and UK targets treated with 0.1% lambda-cyhalothrin. In the first experiment, the number of flies collected using the 30 s on/off treated target treatment was not different from the number of flies collected using the other treatments. In the second experiment, the number of flies collected using the 30 s on/off treated target treatment was not different than the untreated target continuous or 30 s on/off treatments, but was significantly lower than the treated target continuous treatment. The number of flies collected with UK trigger targets was significantly higher than that for alsynite cylinder traps in two experiments. The mean number of flies collected during 22 1h assays using targets was 6.1-fold higher than that for alsynite traps, and the mean number of flies collected during 40 3 h using the targets also was 6.1-fold higher than that for alsynite traps. The results of this study indicate that treated cloth targets may be a viable addition for stable fly control programs.     

Chlamydia-related abortions in cattle from Graubunden, Switzerland

In 2001, the first case of bovine chlamydial abortion was reported in canton Graubunden, Switzerland. In this region, Chlamydophila (Cp.) abortus is endemic in small ruminants. Hence, we aimed to investigate the incidence of chlamydia-related abortions in cattle from Graubunden. During breeding seasons of 2003-2004, formalin-fixed and paraffin-embedded placenta specimens (n = 235) from late-term abortions in cattle were analyzed by histopathology, immunohistochemistry with a Chlamydiaceae-specific monoclonal antibody against chlamydial lipopolysaccharide (LPS), and 2 different polymerase chain reaction (PCR) methods (16 S ribosomal ribonucleic acid [rRNA] PCR, intergenic spacer [IGS-S] PCR), followed by PCR product sequencing. In 149 of 235 cases (63.4%), histopathologic lesions such as purulent and/or necrotizing placentitis were observed. Chlamydial antigen was clearly demonstrated in immunohistochemistry in only 1 of 235 cases (0.4%). Cp. abortus or Cp. psittaci was found in 12 of 235 (5.1%) and 10 of 235 cases (4.2%) by 16 S rRNA PCR and IGS-S PCR, respectively. However, we detected, by 16 S rRNA PCR, 43 of 235 cases (18.3%) to be positive for chlamydia-like organisms. In contrast to the situation in small ruminants in the canton Graubunden, bovine abortion from Cp. abortus seems not to play an important role. Nevertheless, zoonotic potential should be taken into account when handling abortion material from cattle. The significance of chlamydia-like isolates other than Waddlia chondrophila remains an open question in abortion and needs further investigation.     

Seasonal dynamics of synbovine flies (Diptera: Muscidae) during the grazing period in Jarov

Synbovine flies and the seasonal pattern of their occurrence were studied throughout the grazing period in the cattle pastures of the Strakonice district. Skufin's traps were used for catching the flies. The total number of dipterous insects caught during the series of trappings in two- to three-week intervals was 2096. The family Muscidae (23 species) was represented most amply in the sample catches (Musca autumnalis 65.9%, Hydrotaea Meteorica 20.4%, Hydrotaea irritans 4.2%, Haematobosca stimulans 2.6%). The maximum occurrence of haematophagous species was recorded at the beginning and at the end of the grazing season. The maximum occurrence of secretophagous species was recorded in June.     

Genotyping of Babesia bigemina from cattle from a non-endemic area (Switzerland)

In August 2002, bovine anaplasmosis and concurrent infections with Mycoplasma sp. and piroplasms were reported in a cattle herd in an alpine region of Switzerland. The piroplasms were identified by PCR/sequencing of part of the 18S rRNA gene as Babesia bigemina and Theileria of the buffeli/sergenti/orientalis-complex, which have never been diagnosed in Switzerland before. The B. bigemina isolate was genetically characterised at two loci and compared with isolates from Italy, Spain, Turkey, Kenya and Mexico. Analysis of the internal transcribed spacer 2 (ITS2) of the rRNA genes revealed high polymorphism not only among the isolates but even within the isolates, and the presence of two types of the ITS2 in every isolate was confirmed. A dendrogram based on ITS2 sequences showed that the Swiss isolate was most closely related to a Spanish isolate but no sequences of the isolate from Switzerland were identical to any of the other isolates. The isolate from Italy was not positioned in the same cluster as the Swiss and the Spanish isolate. This had been anticipated as the nearest known endemic area of B. bigemina in Central Italy. Sequence analysis of the rhoptry-associated protein-1c gene (rap1c) confirmed the similarity of the Swiss and Spanish isolate. Hence, our molecular analyses of the Swiss B. bigemina isolate did not unequivocally track its geographical origin and the way of introduction remains obscure.     

Control of tsetse flies in Uganda by dipping cattle in deltamethrin

Summary The effect of treating cattle with deltamethrin to control tsetse flies and ticks was investigated on 2 ranches 8 km apart in central Uganda where there is a high risk of trypanosomosis. This area had a moderate challenge ofGlossina pallidipes. The cattle had very low challenge ofRhipicephalus appendiculatus, Amblyomma variegatum, Boophilus decolaratus andRhipicephalus evertsi evertsi, due to regular treatment with dioxathion. On one ranch a dip was charged with deltamethrin to treat cattle regularly for 3 months. The other ranch was used as a control for the tsetse population, but the animals continued to be treated regularly with dioxathion using hand sprays. On the ranch using deltamethrin treatment a reduction of 96.9% in the tsetse population was recorded after 2 treatments at 2 week intervals. Total (100%) control of tsetse was achieved from the fourth treatment up to the end of the trial period. The ranch with dioxathion treatment experienced an overall tsetse reduction of 19.15% during the thirteenth to fifteenth weeks and the factors contributing to this are discussed. However, the mean apparent tsetse density of 4.83 flies/trap/day recorded at the control ranch was significantly different from the mean of 0.81 flies/trap/day (P<0.001) at the ranch using deltamethrin treatment. It was difficult to assess the effect of this product on ticks because of lack of controls. However, there are indications that deltamethrin can also reduce tick populations and the incidence of tick-borne diseases. The possible limitations and practical implications associated with large scale use of this product in the country are discussed.

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Control De Moscas Tsetse En Uganda Mediante La Inmersion De Ganado En Deltametrin

Resumen Se investigó el efecto de tratar ganado condeltametrin para controlar moscas tsetse y garrapatas, en dos ranchos 8 km aparte en Uganda Central, donde prevalece un alto riesgo de tripanosomosis. Esta área tenía un desafio moderado del vectorGlossina pallidipes. El ganado tenía una descarga muy baja deRhipicephalus appendiculatus, Amblyomma variegatum, Boophilus decoloraturus yRiphicephalus evertsi evertsi, debido al tratamiento regular con dioxation. En un rancho el baño de inmersión fue cargado con deltametrin, para bañar el ganado regularmente por tres meses. El otro rancho fue usado como control para evaluar la población de tsetse, pero el ganado siguió siendo tratado regularmente con dioxation, utilizando aspersores de mano. Se alcanzó una reducción de 96.9% en la población de tsetse en el rancho donde el ganado fue tratado con deltametrin, después de dos tratamientos con intervalo de dos semanas. Un control total (100%) de la mosca tsetse fue alcanzado después del cuarto tratamiento, hasta el final del ensayo. El rancho donde el ganado fue tratado con dioxation experimentó una reducción general del 19.15% durante las semanas 13 a 15. Se discuten los factores que contribuyeron a estè reducción. Sin embargo, la media aparente de densidad de tsetse, 4.83 moscas/trampa/día obtenida en el rancho control, fue significativamente differente de la media obtenida en el rancho donde se baño con deltametrin, la que fue 0.81 moscas/trampa/día (P<0.001). Fue dificil detectar el efecto de estè último producto sobre las garrapatas, debido a que no hubo controles. Sin embargo, existen indicaciones de que el deltametrin puede reducir la población de garrapatas y la incidencia de enfermedades hematozoáricas. Se discute las limitaciones posibles e implicaciones prácticas de la utilización en gran escala de este producto en el país.

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Luttre Contre Les Mouches Tse-Tse En Ouganda Par Utilisation De Bains De Deltamethrine Pour Le Traitment Des Bovins

Résumé L'effet du traitement des bovins à la deltamethrine pour lutter contre les mouches tsé-tsé et les tiques a été observé dans 2 ranchs distants de 8 km dans le centre de l'Ouganda où existait un risque élevé de trypanosomose. Cette région présente une densité modérée de glossines. Les bovins étaient très peu infestés parRhipicephalus appendiculatus, Amblyomma variegatum, Boophilus decoloratus etRhipicephalus evertsi evertsi à cause du traitment régulier au dioxathion auquel ils étaient soumis. Dans un des ranchs, les animaux ont été traités régulièrement pendant 3 mois dans un bain de deltamethrine. Ceux de l'autre ranch ont servi de témoins pour les tsé-tsé, mail ils ont continué à être traité régulièrement par des aspersions manuelles de dioxathion. Dans le ranch ayant traité les animaux à la deltamethrine, une réduction de 96,9 p. 100 de la population des tsé-tsé a été relevée après 2 traitements à 2 semaines d'intervalle. L'éradication totale des tsé-tsé a été obtenue à partir due 4e traitement jusqu'à la fin de la période d'experience. Dans le ranch aux animaux témoins, la réduction des tsé-tsé a atteint 19,15 p. 100 de la 13e à la 15e semaines et les facteurs en cause sont discutés. Cependant, la densité moyenne apparente de 4,83 mouches/piège/jour relevée dans le ranch témoin était significativement différente de la moyenne obtenue dans l'autre ranch (0,81 mouches/piège jour) (P<0,001). Il était difficile d'évaluer l'effet de ce produit sur les tiques à cause du manque de témoins. Cependant certaines indications font penser que la deltamethrine peut aussi réduire la population de tiques et l'incidence des maladies transmises par les tiques. Les limites possibles et les implications pratiques associées à une utilisation à grande échelle de ce produit sont discutées.

     

Simulium jenningsi Malloch (Diptera: Simuliidae): a vector of Onchocerca lienalis Stiles (Nematoda: Filarioidea) in New York

Biting flies were collected from the umbilical areas of Onchocerca lienalis-infected cattle in New York (state) from June through September of 1980. Of the 766 flies collected, 705 were Simulium jenningsi. Microfilariae were detected in the midguts of 37 (50%) of 73 females dissected immediately after the flies had fed. The mean number of larvae per positive fly (fly with microfilariae) was 15.2. Third-stage larvae were recovered from 25 (21.9%) of 114 S jenningsi dissected 8 to 13 days after they had fed on the infected cattle; the mean number of 3rd-stage larvae per positive fly was 3.5. Dissections of flies performed on days 1 through 7 after feeding yielded various numbers of 1st and 2nd-stage larvae from the thoracic muscles. Ovarian dissections performed on 304 S jenningsi attacking cattle indicated an overall parous rate of 58%. Naturally occurring infections with filarial larvae indistinguishable from O lienalis were found in 7.3% of the parous females. Three of these flies, or 1.7% of the parous collection, harbored 3rd-stage larvae. The onset of naturally occurring filarial infections in the population of S jenningsi coincided with a peak in the parous rate in late June. Thereafter, filarial infections were generally detected when the parous rate was above 50%.