Attitudes and practices of Queensland dairy farmers to the control of the cattle tick, Boophilus microplus

Objective To determine practices for the control of cattle ticks on dairy farms in Queensland, the attitudes of farmers to tick infestations and to identify opportunities for and barriers against the introduction of non-chemical methods of tick control.
Design A survey of 199 dairy farmers from tick-infested parts of Queensland was undertaken by 20 dairy advisers and stock inspectors from October 1996 to June 1997. The sample was a proportional, random selection of dairy farms from four regions. A personal interview was conducted with each farmer and answers to 134 questions were obtained.
Results and conclusions Most farmers were not concerned by cattle ticks on their own farms, although they believed that ticks are important to the dairy industry. They were most concerned about the development of chemical resistance by cattle ticks. Inadequate facilities and lack of motivation appeared to be the factors most limiting to improving the methods of control. Most farmers claimed to have only small numbers of ticks at worst. Although a control program recom mended by the Queensland Dairyfarmers' Organisation was well regarded by farmers, few had adopted it. Many farmers saw no need to implement a strategic control program.     

The influence of citrus rootstocks on the relationship between the mite Brevipalpus phoenicis and citrus leprosis disease

BACKGROUND: Leprosis is one of the most serious citrus plant diseases. Leprosis‐affected plants, especially sweet orange [Citrus sinensis (L.) Osbeck], which is the most widely cultivated citrus fruit worldwide, show reduced photosynthetic capacity and severe defoliation. The aim was to evaluate the relationship between the Brevipalpus phoenicis (Geijskes) vector mite and citrus leprosis disease in Pera sweet orange plants grafted on different rootstocks. Data were analysed using numerical classification and conventional statistical analysis (ANOVA). RESULTS: Both viruliferous and non‐viruliferous B. phoenicis populations increased in number on plants maintained at low soil water content. Among the evaluated rootstocks, Sunki mandarin proved least favourable for mite population increase. Furthermore, the viruliferous mite population increased more rapidly than the non‐viruliferous mite population. CONCLUSION: The Cleopatra rootstock showed low variability in leaf nitrogen content, low mite number and low leprosis severity, thereby producing the most favourable results. Under appropriate moisture conditions, the Sunki rootstock produced the best results, showing the least severe leprosis. Rangpur lime rootstock grown in soil with varying water content showed the greatest variation in foliar nitrogen content, mite number and severity of leprosis and is considered to be the most difficult rootstock to manage. Copyright © 2012 Society of Chemical Industry     

Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.     

Seminal Leucocytary Profile in Beef Bulls

Despite evidences that seminal leucocytes could affect semen quality, references for the frequency and concentration of these cells in bulls are not available. The aim of this study was to determine the normal concentration of leucocytes in beef bulls and to correlate this characteristic with semen quality. First, 57 bulls from artificial insemination centres were evaluated to obtain the normal leucocytary profile values. Next, 382 bulls were subjected to breeding soundness evaluation. The average concentration of leucocytes in bovine semen was 4.73 × 10⁶/ml. Unsatisfactory bulls showed a higher number of leucocytes/field than that in the satisfactory ones. Logistic regression analysis revealed that the unsatisfactory bulls showed 6.5‐fold more chances of having higher leucocyte counts than satisfactory ones. Values of up to 1 leucocyte/field in the bull ejaculate are considered physiologically normal, whereas >5 leucocytes/field is associated with poor semen quality.     

Tibial osteomyelitis caused by Rhodococcus equi in a mature horse

A 7‐year‐old Paint mare presented for evaluation of a swollen right hindlimb of approximately 6 weeks' duration. Ultrasonography and radiography suggested a severe osteomyelitis and abscessation of the right tibia. Previous treatment included systemic antimicrobial therapy using procaine penicillin G (22,000 u/kg bwt, q. 12 h, i.m.) and gentamicin sulfate (6.6 mg/kg bwt, q. 24 h, i.v.) initially followed by oral doxycycline (10 mg/kg bwt, q. 12 h, per os) and rifampin (5 mg/kg bwt, q. 12 h, per os). Based on the poor prognosis the mare was subjected to euthanasia. Necropsy results subsequently revealed a severe, chronic, focal, necrotising osteomyelitis with localised cellulitis and abscessation. Rhodococcus equi was isolated from the tibia, subcutaneous abscess and from a pectoral abscess found at necropsy. Immunological testing of blood samples obtained ante mortem revealed normal blood lymphocyte phenotyping, but markedly increased IgG and IgM concentrations, indicating an active humoural response. While there have been reports of Rhodococcus equi infection in mature horses this is an area previously unreported in the literature.     

Heliotropium europaeum poisoning of sheep with low liver copper concentrations and the preventive efficacy of cobalt and antimethanogen

In a field experiment in the Mallee district of Victoria, Merlno xBorder Leicester ewes and wethers grazed Heliotropium europaeum (heliotrope) over periods of 3 to 4 months in 4 successive years. By the end of the second year 12% (14 of 120) of the sheep had died; after 4 years the loss attributable to heliotrope was between 18% and 35%. Mortality was not affected by intraruminal treatment with cobalt or antimethanogen. At the end of the experiment the highest concentration of copper in the liver was 1.95 mmol/kg wet weight (approximately 413 micrograms/g dry weight). The relatively low mortality from primary heliotrope poisoning and the low concentration of copper in the liver of sheep grazing the plant are discussed in relation to the contrasting situation that prevails in the Riverina area of New South Wales. The importance of local environmental factors in the management of heliotrope grazing by sheep is emphasised, particularly in relation to the number of seasons in which the plant may be a major component of the diet.