A serological survey of cattle in the Thames-Coromandel district of New Zealand for antibodies to Ross River virus

AIM: To determine if cattle exposed to the southern saltmarsh mosquito (SSM), Aedes camptorhynchus, in the Thames-Coromandel district of New Zealand had been exposed to Ross River virus (RRV).

METHODS: A purposive sampling design was used to test cattle from seven farms located in close proximity to four sites infested with A. camptorhynchus in the Thames-Coromandel district. Sera from 207 cattle were tested for antibodies to RRV, using an ELISA and confi rmatory virus neutralisation test (VNT) as the gold standard.

RESULTS: All 207 cattle tested negative for antibodies to RRV using the ELISA and VNT.

CONCLUSIONS: This study found no evidence of exposure to RRV in cattle in locations in the Thames-Coromandel district of New Zealand where populations of SSM were present.     

Forest fires: An example of self-organized critical behavior

Despite the many complexities concerning their initiation and propagation, forest fires exhibit power-law frequency-area statistics over many orders of magnitude. A simple forest fire model, which is an example of self-organized criticality, exhibits similar behavior. One practical implication of this result is that the frequency-area distribution of small and medium fires can be used to quantify the risk of large fires, as is routinely done for earthquakes.     

Spatial relationship between biodiversity and geodiversity across a gradient of land-use intensity in high-latitude landscapes

Context

‘Conserving Nature’s stage’ has been advanced as an important conservation principle because of known links between biodiversity and abiotic environmental diversity, especially in sensitive high-latitude environments and at the landscape scale. However these links have not been examined across gradients of human impact on the landscape.

Objectives

To (1) analyze the relationships between land-use intensity and both landscape-scale biodiversity and geodiversity, and (2) assess the contributions of geodiversity, climate and spatial variables to explaining vascular plant species richness in landscapes of low, moderate and high human impact.

Methods

We used generalized additive models (GAMs) to analyze relationships between land-use intensity and both geodiversity (geological, geomorphological and hydrological richness) and plant species richness in 6191 1-km² grid squares across Finland. We used linear regression-based variation partitioning (VP) to assess contributions of climate, geodiversity and spatial variable groups to accounting for spatial variation in species richness.

Results

In GAMs, geodiversity correlated negatively, and plant species richness positively, with land-use intensity. Both relationships were non-linear. In VP, geodiversity best accounted for species richness in areas of moderate to high human impact. These overall contributions were mainly due to variation explained jointly with climate, which dominated the models. Independent geodiversity contributions were highest in pristine environments, but low throughout.

Conclusions

Human action increases biodiversity but may reduce geodiversity, at landscape scale in high-latitude environments. Better understanding of the connections between biodiversity and abiotic environment along changing land-use gradients is essential in developing sustainable measures to conserve biodiversity under global change.

     

Using EM and VERIS technology to assess land suitability for orchard and vineyard development

Orchard and vineyard producers conduct preplant site evaluations to help prevent planting permanent tree and vine crops on lands where the crop will not perform to its highest potential or attain its full life expectancy. Physical soil characteristics within specific soil profiles and spatially throughout an orchard influence decisions on land preparation, irrigation system selection, horticultural choices, and nutrient management. Producers depend on soil surveys to help them understand the soil characteristics of the land and may be interested in technology that provides additional information. Electromagnetic induction (EM38) and four-probe soil resistance sensors (VERIS) are being used in combination with global positioning systems to map spatial variability of soils using apparent soil electrical conductivity (ECa). The hypothesis evaluated in this study is whether rapid, in situ, and relatively low-cost methods of measuring ECa (EM38 and VERIS) can effectively identify and map physical soil variability in non-saline soils. The supposition is that in non-saline soils, ECa levels will relate well to soil texture and water-holding capacity and can be used to map physical soil variability. In turn, the information can be used to guide decisions on preplant tillage, irrigation system design, water and nutritional management, and other horticultural considerations. Two sites in the Sacramento Valley were mapped each with EM38 and VERIS methods. Site-specific management zones were identified by each provider on ECa maps for each site, and then soil samples were collected by University of California researchers to verify these zones. Results showed that on non-saline soils, ECa measured with both EM38 and VERIS correlate with physical soil properties such as gravel, sand, silt, and clay content but the relationship between conductivity and these physical soil properties varied from moderately strong to weak. The strength of the correlation may be affected by several factors including how dominant soil texture is on conductivity relative to other soil properties and on methods of equipment operation, data analysis and interpretation. Overall, the commercial providers of ECa surveys in this study delivered reasonable levels of accuracy that were consistent with results reported in previous studies. At one site, an ECa map developed with VERIS provided more detail on physical soil variability to supplement published soil surveys and aided in the planning and development of a walnut orchard. At a second site, almond yield appeared to correlate well with distinctly different soil zones identified with EM38 mapping.     

Serratospiculosis in a New Zealand Falcon (Falco novaeseelandiae)

CASE HISTORY: An adult New Zealand falcon was presented with metacarpal fractures in the left wing.

CLINICAL FINDINGS: In addition to the fractures, radiographs revealed an area of opacity in the air sacs. A few days after hospitalisation and initiation of treatment of the fractures, the bird developed signs of respiratory disease; the area of opacity was found to have increased in size and density. Treatment with antibiotics and nebulisation was commenced; the bird initially responded but respiratory signs subsequently worsened and the bird died. At necropsy, air sacculitis and bronchopneumonia were associated with numerous nematodes in the air sacs, which were morphologically consistent with Serratospiculum guttatum.

DIAGNOSIS: Serratospiculosis

CLINICAL RELEVANCE: The discovery of this parasite and the associated disease for the first time in New Zealand indicates that it should be considered in the differential diagnosis of respiratory disease in falcons and possibly other raptors in New Zealand.     

Importance of Staphylococcus hyicus ssp hyicus as a cause of arthritis in pigs up to 12 weeks of age

Lame pigs, up to 12 weeks of age, were necropsied to establish a diagnosis. Of 175 pigs examined, 165 were confirmed to have arthritis by histopathological examination of joint tissues. Lesions were most common in the elbow and tarsal joints and least common in the joints of the feet. Typically, there was severe fibrinopurulent inflammation of synovial membranes regardless of the bacteria isolated. A bacterial aetiology was found in 114 (69%) of the 165 pigs. In arthritic pigs in which an aetiology was established the causative agents were Staphylococcus hyicus ssp hyicus (24.6%), Streptococcus equisimilis (26.3%), Actinomyces pyogenes (13.2%), Staphylococcus aureus (7.9%) and Haemophilus parasuis (7.9%). While gender did not affect the prevalence of arthritis, there was an age influence, most of the pigs culled for arthritis being under 6 weeks of age.     

Spur behaviour in almond trees: relationships between previous year spur leaf area, fruit bearing and mortality

In mature almond (Prunus dulcis) orchards, the majority of crop is borne on spurs (short, proleptic shoots) that can live for several years and can produce from one to five fruits. Previous research has led to the hypothesis that spur longevity is related to spur light exposure, cropping and age. However, limited quantitative data are available to substantiate these hypotheses. The objective of this study was to determine spur characteristics that were most highly correlated with spur productivity and longevity in mature, bearing almond trees. Previous year spur leaf area was strongly related to spur viability and flowering; the greater the leaf area in the previous year, the higher the probability of spur survival into the next year and the higher the probability for the spur to bear one or more flowers. Previous year bearing also appeared to influence viability and return bloom, especially in spurs with low leaf area. These results suggest that spur source-sink balance is basic to the life cycle of almond spurs. Furthermore, the results are consistent with the hypothesis that spurs are semi-autonomous organs with respect to carbohydrate balance for much of the growing season. Finally, this information provides general thresholds for maintaining spur viability and productivity that will be useful for developing and evaluating tree training systems and orchard management practices.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.