The Role of the Bark Beetle, Hylastes ater (Coleoptera: Scolytidae), as a Sapstain Fungi Vector to Pinus radiata Seedlings: A Crisis for the New Zealand Forestry Industry?

The role of the bark beetle Hylastes ater in the re-establishment of Pinus radiata forest in New Zealand is discussed. H. ater was found to be a dominant factor in seedlings mortality in the first year following planting. However, seedling mortality is usually relatively low. In contrast, it was found the large numbers of seedlings were sub-lethally damaged by H. ater feeding attempts, particularly in high risk sites. High risk sites were identified as sites that were harvested during March and April (autumn) when the peak flight activity of H. ater occurred, and subsequently planted with P. radiata seedlings the following winter. H. ater was found to vector sapstain fungi to seedlings during feeding attempts, and a strong relationship between the severity of damage and presence of sapstain fungi was identified. The role of H. ater as a vector of these fungi and the potential implications to the New Zealand forest industry are discussed.     

Internal fixation of a greater tubercle fracture in an adolescent horse: A case report

This report describes the diagnosis of a fracture of the greater tubercle of the humerus and successful repair with 2 cancellous bone screws in a 420 kg adolescent horse.     

Demographic network and multi-season occupancy modeling of Rana sylvatica reveal spatial and temporal patterns of population connectivity and persistence

Many populations are spatially structured with frequent extinction–colonization events. A clear understanding of these processes is necessary for making informed and effective management decisions. Due to the spatially and temporally dynamic nature of many systems, population connectivity and local extinction–colonization processes can be difficult to assess, but graph theoretic and occupancy modeling approaches are increasingly being utilized to answer such vital ecological questions. In our study, we used 6 years of egg mass counts from 34 ponds for Rana sylvatica to parameterize spatially explicit demographic network models. Our models revealed that the studied populations have spatial structure with strong source–sink dynamics. We also assessed the colonization and persistence probability of each pond using multi-season occupancy modeling. We observed extreme fluctuation in reproductive effort among years, resulting in variable levels of connectivity across the landscape. Pond colonization and persistence were most influenced by local population dynamics, but colonization was also affected by precipitation. Our demographic network model had moderate ability to predict reproductive effort, but accuracy was hindered by variation in annual precipitation. Source populations had higher colonization and persistence rates as well as a greater proportion of ravine habitat within 1,000 m than sink populations. By linking a spatially explicit connectivity model with a temporal occupancy/persistence model, we provide a framework for interpreting patterns of occupancy and dispersal that can serve as an initial guide for future habitat management and restoration.     

Landscape-level interactions between topoedaphic features and nitrogen limitation in tallgrass prairie

Transects across watersheds with varying fire histories and remotely-sensed data were used to study vegetation-resource interactions in a tallgrass prairie in Kansas. Paired plots (fertilized, control) were established along these transects and sampled for grass and forb biomass during the 1989 and 1990 growing seasons. Fertilization resulted in significant production responses in grass and total biomass on the west slopes of the annually burned (ID) and infrequently burned (N4) watersheds for both years (p = 0.05). In 1989, fertilization also produced a significant increase in grass biomass on the west slope of the unburned transect (p = 0.05), however, total production was not significantly increased. East slopes were insensitive to nitrogen additions. Differences in production response along these transects were assessed by testing the interaction between fertilization response and slope position. Significant interactions occurred on both 1D and N4, but only in 1990.Production data for both years were also compared to Normalized Difference Vegetation Index (NDVI) values derived from thematic mapper (TM) images for 1989 and 1990. When differences among transects or watersheds were statistically different, a positive relationship between NDVI and biomass was observed. NDVI values accurately reflected the spatial patterns of production along these transects for both years although not necessarily the magnitude.     

What is your diagnosis? Biopsy impression smear of a hepatic mass in a yearling Thoroughbred filly

A 1-year-old Thoroughbred filly was presented to the Cornell University Hospital for Animals with a 10-day history of fever, diarrhea, inappetance, and hypodipsia. Clinical pathology abnormalities found by the referring veterinarian included erythrocytosis, hyperproteinemia, and increased serum gamma-glutamyltransferase and lactate dehydrogenase activities. At Cornell University, the laboratory abnormalities were confirmed and also included thrombocytosis and hypoglycemia. Erythrocytosis persisted despite vigorous fluid therapy. Ultrasound examination revealed an extremely enlarged liver with abnormal echogenicity and a 21 x 25-cm hepatic mass with varied echogenicity. Imprints of an ultrasound-guided biopsy of the mass revealed a neoplastic epithelial population of uncertain origin, although the cells did not resemble hepatocytes. Together with the presenting signs, signalment, ultrasonographic findings, and persistent erythrocytosis, the cytologic findings were considered to be most consistent with hepatoblastoma. Histopathologic examination of the mass at necropsy confirmed the diagnosis and findings also included bone marrow erythroid hyperplasia. Serum erythropoietin concentration was 28.0 mU/mL (reference interval 1.0-11.8 mU/mL), supporting erythropoietin production by the tumor and secondary inappropriate erythrocytosis. To our knowledge, this report is the first to document secondary erythrocytosis with increased erythropoietin concentration in a horse with hepatoblastoma, and also the first to describe the cytopathologic features of this rare tumor.     

Salinomycin toxicosis in horses

CASE DESCRIPTION: A 4-month-old American Paint filly was evaluated because of sudden onset of ataxia that progressed to recumbency. Five additional horses from the same and neighboring premises developed signs of poor performance, generalized weakness, ataxia, and recumbency; 2 of those horses were also evaluated. A new batch of a commercial feed supplement had been introduced to the horses' diet on each farm within the preceding 3 days. CLINICAL FINDINGS: Other than recumbency, findings of physical and neurologic examinations of the foal were unremarkable. The other 2 horses had generalized weakness and mild ataxia, and 1 horse also had persistent tachycardia. The foal had mild leukocytosis with neutrophilia, hyperglycemia, and mildly high serum creatine kinase activity. Results of cervical radiography, CSF analysis, and assessments of heavy metals and selenium concentrations in blood and vitamin E concentration in serum were within reference limits. Feed analysis revealed high concentrations of the ionophore antimicrobial salinomycin. TREATMENT AND OUTCOME: The 5 affected horses survived, but the foal was euthanized. At necropsy, a major histopathologic finding was severe vacuolation within neurons of the dorsal root ganglia, which was compatible with ionophore toxicosis. The surviving horses developed muscle atrophy, persistent weakness, and ataxia. CLINICAL RELEVANCE: In horses, ionophore toxicosis should be considered as a differential diagnosis for acute weakness, ataxia, recumbency, or sudden death. Furthermore, ionophore toxicosis should be considered as a cause of poor performance, weakness, muscle wasting, and cardiac arrhythmias in horses. Surviving horses may have impaired athletic performance.     

Determination of cotton nitrogen status with a handheld chlorophyll meter

The ability of a hand‐held chlorophyll meter (SPAD‐502 Chlorophyll Meter³, Minolta Camera Co., Ltd., Japan) to determine the N status of cotton (Gossypium hirsutum L.) was studied at field sites in Alabama and Missouri. Meter readings on the uppermost fully‐expanded leaf were compared to leaf‐blade N and petiole NO₃‐N at first square, first bloom and midbloom as to their seed cotton yield predictive capability. Nitrogen was applied at rates of 0, 45, 90, 135, 180 and 225 kg ha^‐1 to establish a range of cotton chlorophyll levels, tissue N concentrations, and seed cotton yields. A typical curvilinear cotton yield response to N fertilizer was observed in Alabama experiments.

Because of adverse weather conditions, cotton yield in Missouri experiments did not respond to N. Chlorophyll meter readings were significantly correlated to leaf‐blade N concentration at all three stages of growth for all experiments. In Alabama, chlorophyll meter readings compared favorably to leaf‐blade N and petiole NO₃‐N with respect to their seed cotton yield predictive capability at all three stages of growth. It appears that hand‐held chlorophyll meters would be as reliable as leaf‐blade N and petiole NO₃‐N for predicting supplemental N fertilization requirements of cotton. However, more research will be required prior to use of chlorophyll meter readings for routine cotton‐N recommendation purposes.