Inhibition of oviposition in the cattle tick Boophilus microplus by certain acaricides

Doses of ten acaricides, ranging from 2.5 to 10 μg, induced about 10-60% mortality and inhibited oviposition in engorged Boophilus microplus as well as preventing larval hatching from the eggs. The effects of the acaricides were dose dependent. The efficacy of acaricides in reducing the reproductive potential (inhibition of oviposition × inhibition of hatching/100) was in the following order: dimethoate > dioxathion > naled > diazinon > chlordimeform > carbaryl > trichlorphon > phosphamidon > gamma-HCH > fenitrothion. Most of the acaricides also retarded the oviposition cycle, delaying the peak activity by 4-8 days. The ovarian development in control ticks reached its peak between the 5th and 7th days before decreasing gradually and ceasing completely between the 16-20th days after engorgement. The protein content of the ovaries and the rate of incorporation of [¹⁴C]glycine into the tissues followed a similar pattern. Carbaryl, fenitrothion and naled inhibited these activities. Chlordimeform stimulated [¹⁴C]glycine incorporation and increased the ovarian protein content up to the 13th day before resorption of the oocytes. The eggs from treated ticks were mostly non-viable and contained more protein; those from dioxathion, carbaryl and chlordimeform treatments had a higher dry weight than the control.     

Oral vaccination of chickens with the V4 strain of Newcastle disease virus. Cooked and raw white rice as a vehicle

Summary Uncooked white rice and cooked white rice were tested as vehicles for the V4 strain of oral Newcastle disease vaccine. The results of feeding experiments were evaluated by the measurement of haemagglutination inhibition antibodies against Newcastle disease virus. Little of the virus applied to uncooked white rice could be recovered, even immediately after mixing, whereas when the virus was applied to cooked white rice most of it could be recovered. In 4 separate experiments, chickens failed to respond serologically to vaccine supplied on uncooked white rice. In all of 4 experiments with cooked white rice, there were serological responses in vaccinated chickens, from 45% to 100% of the chickens developing titres sufficiently high to indicate protection against challenge with virulent virus. Development of haemagglutination inhibition antibodies in some control chickens indicated the ability of the vaccine virus for lateral spread or persistence in the environment.

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Vacunacion Oral De Pollos Con La Cepa V4 Del Virus De La Enfermedad De Newcastle Utilizando Como Vehiculo Arroz Blanco Cocinado Y No Cocinado

Resumen Se utilizo arroz blanco sin cocinar y cocinado como vehículo para la vacuna oral con la cepa V4 de la enfermedad de Newcastle. Los resultados de los experimentos fueron evaluados mediante la determinación de los anticuerpos de inhibición-hemaglutinación contra el virus de la enfermedad de Newcastle. Poca cantidad del virus de la enfermedad de Newcastle pudo recuperarse en el arroz crudo, incluso inmediatamente despues de revolverlo, mientras que la mayoría del virus pudo recuperarse del arroz cocinado. En 4 experimentos separados, los pollos no respondieron serológicamente a la vacuna aplicada en arroz blanco crudo. En los 4 experimentos con arroz cocinado, se detectaron respuestas serológicas en los pollos vacunados; 45% a 100% de los pollos desarrollaron títulos suficientes como para resistir la descarga de virus virulento. El desarrollo de anticuerpos de inhibición-hemaglutinación en algunos de los pollos controles indicó la capacidad del virus vacunal para dispersarse lateralmente y persistir en el ambiente.

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Vaccination Par Voie Orale De Poulets Avec La Souche V4 Du Virus De La Maladie De Newcastle Avec Comme Support Du Riz Blanc Cuit Et Du Riz Blanc Cru

Résumé Du riz blanc crû et du riz blanc cuit ont été testés en tant que supports de la souche de virus V4 du vaccin contre la maladie de Newcastle. Les résultats de ces expériences d'alimentation ont été évalués par la mesure des anticorps d'inhibition de l'hémagglutination du virus de la maladie de Newcastle.Seule une petite quantité du virus mélangé dans le riz blanc crû a pu être récupérée même immédiatement après le mélange. Par contre la majeur partie du virus a pu être récupérée lorsqu'il s'agissait du riz blanc cuit.Dans 4 expériences séparées, ils n'y avait pas de réponses sérologiques chez les poulets recevant du vaccin ajouté au riz blanc crû. Dans toutes les 4 expériences avec du riz blanc cuit, les réponses sérologiques ont été positives chez les poulets vaccines, 45p. 100 à 100p. 100 des poulets développant des titres suffisamment élevés pour démontrer une protection contre l'épreuve avec du virus virulent. Le développement des anticorps d'inhibition de l'hémagglutination chez quelques poulets témoins a montré la capacité de diffusion latérale ou la persistance dans l'environnement du virus.

     

Implications of rising costs of registering agrochemicals

The increased number and complexity of the requirements for registration of agrochemicals are causing a steep rise in the costs of research and development and therefore in the price of agrochemicals. It now takes about 8–9 years for an agrochemical to be developed and marketed, at a probable cost of 10–20 million US dollars, and each of the individual tests required may cost up to US$ 500 000. A continuation of these trends would have serious consequences for industry, farmers, consumers and the developing countries. So far, the agrochemical industry has been able to continue to produce the new and improved materials necessary to combat changing pest attack: whether it can continue to do so may depend upon whether or not registration requirements are increased. Unnecessary requirements must be identified and eliminated, and any new demands must be fully justified in terms of the cost involved and of the ensuing benefits. However, if the search for greater safety were to be pushed to even greater lengths, so that costs exceed what the market will bear, the extra costs would have to be borne by the authorities and, ultimately, by the taxpayer.     

Characterization of Mannheimia (Pasteurella) haemolytica leukotoxin interaction with bovine alveolar macrophage beta2 integrins

Mannheimia (Pasteurella) haemolytica, the etiologic agent of bovine pneumonic mannheimiosis, produces an exotoxic leukotoxin. The leukotoxin (LktA) is a member of the RTX (repeats in toxin) family of bacterial cytolysins and is distinguished from other toxins by its unique target cell specificity to ruminant leukocytes occurring through binding to a specific receptor. We have demonstrated previously that the beta2 integrin LFA-1 is a receptor for LktA in bovine leukocytes and is involved in leukotoxin-induced biological effects. However the subunits within LFA-1 involved in binding to LktA, and post-binding signaling leading to cellular activation have not been well characterized. The purpose of our study was to pinpoint these precise subunits on bovine alveolar macrophages and to characterize their interaction with LktA. The results in this study indicate that although LktA can efficiently bind to the CD18 subunit of both LFA-1 and Mac-1, post-binding signaling events including elevation of intracellular calcium and CD18 tail phosphorylation are only observed through LFA-1. Furthermore, LktA also binds to the CD11a subunit of LFA-1. LktA binding to CD11a could be inhibited by a small molecule inhibitor of the I(inserted)-domain, the major ligand binding interface on CD11a. I-domain inhibition significantly blunts LktA-induced intracellular calcium elevation and tyrosine phosphorylation of the CD18 tail. Based on our results we suggest that LFA-1 serves as the functional leukotoxin receptor on bovine alveolar macrophages.     

A plant miRNA contributes to antibacterial resistance by repressing auxin signaling

Plants and animals activate defenses after perceiving pathogen-associated molecular patterns (PAMPs) such as bacterial flagellin. In Arabidopsis, perception of flagellin increases resistance to the bacterium Pseudomonas syringae, although the molecular mechanisms involved remain elusive. Here, we show that a flagellin-derived peptide induces a plant microRNA (miRNA) that negatively regulates messenger RNAs for the F-box auxin receptors TIR1, AFB2, and AFB3. Repression of auxin signaling restricts P. syringae growth, implicating auxin in disease susceptibility and miRNA-mediated suppression of auxin signaling in resistance.     

One-step fabrication of supramolecular microcapsules from microfluidic droplets

Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbit[8]uril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy.     

Metrics for quantifying antimicrobial use in beef feedlots

Accurate antimicrobial drug use data are needed to enlighten discussions regarding the impact of antimicrobial drug use in agriculture. The primary objective of this study was to investigate the perceived accuracy and clarity of different methods for reporting antimicrobial drug use information collected regarding beef feedlots. Producers, veterinarians, industry representatives, public health officials, and other knowledgeable beef industry leaders were invited to complete a web-based survey. A total of 156 participants in 33 US states, 4 Canadian provinces, and 8 other countries completed the survey. No single metric was considered universally optimal for all use circumstances or for all audiences. To effectively communicate antimicrobial drug use data, evaluation of the target audience is critical to presenting the information. Metrics that are most accurate need to be carefully and repeatedly explained to the audience.     

A description of local pig feeding systems in village smallholder farms of Western Kenya

We used face-to-face interviews to gather data on pig feeding practices in rural Busia District, Kenya. We visited 164 pig farms three times in the course of the study period. The pigs were weighed in kilograms during the visits. Feeds offered to pigs were described during the interviews. The most frequently fed feedstuffs were; ground maize or "ugali" (88%), kitchen leftovers (83%) and dried fish locally called "omena" (78%). Farmers provided pigs with water separately from the feeds. Sweet potatoes, "ugali" and cassava were available and could serve as good sources of energy for pigs in the district. Fruits and vegetables were also available and could potentially act as good sources of vitamins. Sweet potato vines, "omena" fish and slaughter blood were available and could provide pigs with proteins. The average daily gain (ADG) for pigs ≤ 5 months of age, pigs of 5.1-9.9 months of age and pigs of ≥ 10 months old was 94.5 (± 43), 127 (± 49.8) and 99 (± 92) g, respectively (p = 0.000). This study has outlined the different local pig feeds available in Busia district. We recommend two things: first, additional research on nutrient composition for the identified local feeds, and second, developing and validating simple local feed combinations that would achieve balanced local pig rations.     

Risk factors associated with occurrence of nematodes in free range pigs in Busia District,Kenya

Nematode infections are a serious constraint to pig production, especially where free range pig keeping is practiced. This study investigated the epidemiology of nematodes in free range pigs in Busia District, Kenya. Three hundred and six pigs from 135 farms were sampled for faeces that were analysed for nematode eggs per gram (EPG) of faeces using the McMaster technique. The nematode eggs were also identified to genus and species based on morphology. A questionnaire on risk factors was also administered to the pig owners. The overall prevalence and mean nematode EPG were 84.2% and 2,355, respectively. The nematode eggs were identified as those belonging to Oesophagostomum spp. (75%), Strongyloides ransomi (37%), Ascaris suum (18%), Metastrongylus spp. (11%), Trichuris suis (7%) and Physocephalus sexalatus (3%). The prevalence of nematodes was positively correlated (p < 0.05) with the amount of rainfall in the division of the pigs' origin (all nematodes except S. ransomi). The prevalence of nematodes was also associated with the age of the pigs. A lower burden of nematodes was associated (p < 0.05) with a history of deworming (A. suum) and the provision of night housing (S. ransomi and Metastrongylus spp.). In conclusion, this study has provided information on nematode infections and the associated risk factors for free range pigs in Busia District, which can be used when implementing integrated control measures.