Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor

The American beekeeping industry continually experiences colony mortality with annual losses as high as 43%. A leading cause of this is the exotic, ectoparasitic mite, Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae). Integrated Pest Management (IPM) options are used to keep mite populations from reaching lethal levels, however, due to resistance and/or the lack of suitable treatment options, novel controls for reducing mites are warranted. Oxalic acid for controlling V. destructor has become a popular treatment regimen among commercial and backyard beekeepers. Applying vaporized oxalic acid inside a honey bee hive is a legal application method in the U.S., and results in the death of exposed mites. However, if mites are in the reproductive stage and therefore under the protective wax capping, oxalic acid is ineffective. One popular method of applying oxalic is vaporizing multiple times over several weeks to try and circumvent the problem of mites hiding in brood cells. By comparing against control colonies, we tested oxalic acid vaporization in colonies treated with seven applications separated by 5 d (35 d total). We tested in apiaries in Georgia and Alabama during 2019 and 2020, totaling 99 colonies. We found that adult honey bees Linnaeus (Hymenoptera: Apidae), and developing brood experienced no adverse impacts from the oxalic vaporization regime. However, we did not find evidence that frequent periodic application of oxalic during brood-rearing periods is capable of bringing V. destructor populations below treatment thresholds.     

Soybean meal alters autochthonous microbial populations, microvilli morphology and compromises intestinal enterocyte integrity of rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout were fed either a diet containing fishmeal (FM) as the crude protein source or a diet containing 50% replacement with soybean meal (SBM) for 16 weeks. An enteritis-like effect was observed in the SBM group; villi, enterocytes and microvilli were noticeably damaged compared with the FM group. The posterior intestine microvilli of SBM-fed fish were significantly shorter and the anterior intestine microvilli significantly less dense than the FM-fed fish. Electron microscopy confirmed the presence of autochthonous bacterial populations associated with microvilli of both fish groups. Reduced density of microvilli consequently led to increased exposure of enterocyte tight junctions, which combined with necrotic enterocytes is likely to diminish the protective barrier of the intestinal epithelium. No significant differences in total viable counts of culturable microbial populations were found between the groups in any of the intestinal regions. A total of 1500 isolates were tentatively placed into groups or genera, according to standard methods. Subsequent partial 16S rRNA sequencing revealed species that have not been identified from the rainbow trout intestine previously. Compared with the FM group levels of Psychrobacter spp. and yeast were considerably higher in the SBM group; a reduction of Aeromonas spp. was also observed.     

Soil fertility ‐ crop genotype associations and interactions 1

This paper discusses the opportunities to combine the efforts of plant geneticists and soil scientists to develop crop varieties adapted to the existing soil conditions and techniques used for production. Such research should result in improved varieties for the best as well as poorest of soil and production situations.     

Short-term effects of nitrogen on methane oxidation in soils

 The short-term effects of N addition on CH₄ oxidation were studied in two soils. Both sites are unfertilized, one has been under long-term arable rotation, the other is a grassland that has been cut for hay for the past 125 years. The sites showed clear differences in their capacity to oxidise CH₄, the arable soil oxidised CH₄ at a rate of 0.013 μg CH₄ kg^–1 h^–1 and the grassland soil approximately an order of magnitude quicker. In both sites the addition of (NH₄)₂SO₄ caused an immediate reduction in the rate of atmospheric CH₄ oxidation approximately in inverse proportion to the amount of NH₄ ⁺ added. The addition of KNO₃ caused no change in the rate of CH₄ oxidation in the arable soil, but in the grassland soil after 9 days the rate of CH₄ oxidation had decreased from 0.22 μg CH₄ kg^–1 h^–1 to 0.13 μg CH₄ kg^–1 h^–1 in soil treated with the equivalent of 192 kg N ha^–1. A ¹⁵N isotopic dilution technique was used to investigate the role of nitrifiers in regulating CH₄ oxidation. The arable soil showed a low rate of gross N mineralisation (0.67 mg N kg^–1 day^–1), but a relatively high proportion of the mineralised N was nitrified. The grassland soil had a high rate of gross N mineralisation (18.28 mg N kg^–1 day^–1), but negligible nitrification activity. It is hypothesised that since there was virtually no nitrification in the grassland soil then CH₄ oxidation at this site must be methanotroph mediated. Received: 31 October 1997     

Causes of death and illness in the native sheep of North Ronaldsay, Orkney. I. Adult sheep

Post-mortem examinations on 71 native sheep found dead on the island of North Ronaldsay, Orkney in four visits between April 1983 and July 1985 were carried out. The sheep in this almost feral flock have access to a small area of unmanaged moorland pasture but are otherwise restricted to the foreshore where they subsist largely on Laminaria spp. and other seaweeds. Young adult animals died largely of heavy parasite burdens combined with inadequate nutrition, while the older sheep often starved because of severe dental disease precipitated by heavy deposits of tartar on the cheek teeth--rarely seen in sheep on a more conventional diet. Other underlying metabolic conditions, such as the extensive mineralization of the kidney medulla in many mature sheep, may be debilitating. The pathological findings suggest that adaptation to the peculiar environmental rigours and dietary restrictions on North Ronaldsay is less complete than has previously been assumed.     

Grey seal (Halichoerus grypus) milk composition and its variation over lactation

Analysis of 56 samples of grey seal milk produced a mean composition of 50% fat, 36.2% water, 12% protein, 0.7% lactose and 0.8% ash. For the first 3 days of lactation the fat content was particularly low while the water content was high, but during lactation the fat content increased whilst the water content fell. No trends were seen in protein, lactose or ash content.     

Pronuclear Embryo Yield in Canindé and Saanen Goats for DNA Microinjection

The objective of this study was to examine the effect of donor breed on pronuclear‐stage embryo yield to be used for DNA microinjection in a transgenesis goat program. Twelve Canindé and twelve Saanen goats were heat synchronized using a progestagen‐cloprostenol treatment. Forty‐eight hours before the sponge removal, superovulation was induced with a total administration of 4.4 mg/kg bodyweight NIH‐FSH‐P1, given twice daily in decreasing doses over 3 days. In addition, goats received 100 μg of GnRH and they were hand‐mated at 36 and 48 h after progestagen removal. Embryo recovery was performed by oviduct flushing at 72 h after sponge removal. Embryos were microinjected with a DNA construct and noticeable swelling of the nuclei was the criterion for successful microinjection. The total diameter, cytoplasm diameter, zona pellucida thickness and pronuclei diameter were measured for each microinjected embryo. A higher (p < 0.05) percentage of fertilized ova was observed in Canindé (89.9%) than Saanen (36.2%) goats. In addition, Canindé donors produced a higher percentage of pronuclear embryos when compared with Saanen: 72.5% vs 20.6% (p < 0.05), respectively. Successful microinjection was verified in 96.7% and 73.3% of times in Canindé and Saanen embryos, respectively (p < 0.05). Significant differences were observed for all morphometric parameters except for cytoplasm diameter. In conclusion, under our study experimental conditions, Canindé were more efficient than Saanen goats concerning the pronuclear embryo yield and manipulation. The use of Canindé goats in transgenesis programs could be increase the interest in their breeding and could be contribute to saving them from extinction.     

Use of dual energy x-ray absorptiometry for noninvasive body composition measurements in clinically normal dogs

OBJECTIVE: To determine quantitative values for components of body composition in clinically normal dogs of various breeds by use of dual energy x-ray absorptiometry (DEXA) and validate the precision and accuracy of DEXA technology in dogs. ANIMALS: 103 clinically normal sexually intact adult dogs. PROCEDURE: In a cross-sectional study, Beagles, Pembroke Welsh Corgis, Golden Retrievers, Great Danes, Pointers, Rottweilers, and nonpurebred dogs received total body DEXA scans. For the validation portion of the study, the results of DEXA scans of 6 dogs were compared with values obtained by chemical analyses of tissues from euthanatized dogs to determine the accuracy of this modality in dogs. RESULTS: Results (coefficient of variation) of the precision tests ranged from 0.10% for lean tissue to 5.19% for fat tissue, whereas accuracy tests revealed a difference between percentage bone mineral content and ash values. Body composition differed by sex, such as higher lean tissue and bone mineral content in males within some breeds, and among breeds. Regardless of body size or weight, the percentage of body weight that was bone mineral ranged from 3 to 4.0% [corrected]. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this cross-sectional study provide valuable body composition data for clinically normal adult dogs, which may have research and clinical applications.