Thromboembolic meningocephalitis caused by Haemophilus somnus infection in a bull calf-a new disease in New Zealand

Thromboembolic meningoencephalitis (TEME) caused by Huemophilus somnus infection was diagnosed for the first time in New Zealand in an eight month old bull calf. Clinical signs included pyrexia, excessive salivation, recumbency, opisthotonus and rigidity of the front legs. Multiple red, malacic foci (1-10 mm in diameter) were visible grossly on the surface of the cerebrum and cerebellum, and were scattered throughout the brain parenchyma. Histologically these lesions consisted of focal haemorrhage, necrosis and neutrophilic infiltration. Fibrin thrombi and colonies of gram negative bacteria were present in many small blood vessels within necrotic foci. An organism with the morphological and biochemical characteristics of Haemophilus somnus was cultured from the brain. Although TEME is an important disease of feedlot cattle in North America and Europe it is relatively uncommon in cattle grazing pasture and is therefore unlikely to become a major problem in New Zealand.     

Spatial epidemiology of the Asian honey bee mite (Varroa destructor) in the North Island of New Zealand

We describe the spatial epidemiology of Varroa destructor infestation among honey bee apiaries in the greater Auckland area of the North Island of New Zealand. The study population was comprised of 641 apiaries located within the boundaries of the study area on 11 April 2000. Cases were those members of the study population declared Varroa-infested on the basis of testing conducted between April and June 2000. The odds of Varroa was highest in apiaries in the area surrounding transport and storage facilities in the vicinity of Auckland International Airport. A mixed-effects geostatistical model, accounting for spatial extra-binomial variation in Varroa prevalence, showed a 17% reduction in the odds of an apiary being Varroa infested for each kilometre increase in the squared distance from the likely site of incursion (95% Bayesian credible interval 7–28%). The pattern of spatially autocorrelated risk that remained after controlling for the effect of distance from the likely incursion site identified areas thought to be ‘secondary’ foci of Varroa infestation initiated by beekeeper-assisted movement of infested bees. Targeted investigations within these identified areas indicated that the maximum rate of local spread of Varroa was in the order of 12 km/year (interquartile range 10–15 km/year).     

Extraction of newly immobilized n from an illinois mollisol using aqueous phenol

Studies were conducted on an ¹⁵N-enriched Illinois Mollisol (Flanagan silt loam) to determine the extractability of newly immobilized N with aqueous phenol (45%, v/v). In comparison to mild extradants proposed as indexes of plant available N (i.e. 10 mw NaHCO₃ and hot 10 m CaCl₂), phenol showed the highest selectivity for the immobilized N, both with regard to the amount of biomass N extracted and the magnitude of the extractability ratio (ER). Aqueous phenol was also more selective in removing the immobilized N than reagents used for extraction of soil organic matter (i.e. 150 m Na₄P₂O₇ and 100 m KOH). Results with soils incubated for up to 120 days showed that the amount of ¹⁵N extracted with aqueous phenol fluctuated with time and was related to changes in the soil microbial population, e.g. ER was highest when the bacterial population was maximal. Aqueous phenol shows promise as a selective extradant of potentially-available (labile) organic N in soils.