Preventing introduction and spread of Dermanyssus gallinae in poultry facilities using the HACCP method

Preventing the establishment of ectoparasitic poultry red mite (Dermanyssus gallinae) populations is key in ensuring welfare and egg production of laying hens and absence of allergic reactions of workers in poultry facilities. Using the Hazard Analysis and Critical Control Point method, a panel of experts identified hazards and associated risks concerning the introduction and spread of this mite in poultry facilities. Together we provide an overview of possible corrective actions that can be taken to prevent population establishment. Additionally, a checklist of the most critical control points has been devised as management tool for poultry farmers. This list was evaluated by Dutch and British poultry farmers. They found the checklist feasible and useful.     

Cardiovascular and respiratory responses associated with limb autotomy in the blue crab, Callinectes sapidus

Cardiovascular and respiratory variables were recorded in the blue crab, Callinectes sapidus, during injury and subsequent autotomy of a chela. Cardiac function and haemolymph flow rates were measured using a pulsed-Doppler flowmeter. Oxygen uptake was recorded using an intermittent flow respirometry system. Crabs reacted to the loss of a chela with a rapid increase in heart rate, which was sustained for 2 h. Stroke volume of the heart also increased after the chela was autotomized. A combined increase in heart rate and stroke volume led to an increase in cardiac output, which was maintained for an hour after the loss of a chela. There was also differential haemolymph perfusion of various structures. There was no change in perfusion of the anterolateral arteries or posterior and anterior aortae, during injury of the chela or subsequent autotomy. Haemolymph flow rates did increase significantly through the sternal artery during injury and immediately following autotomy of the chela. This was at the expense of blood flow to the digestive gland: a sustained decrease in haemolymph flow through the hepatic arteries occurred for 3 h following autotomy. Fine-scale cardiac changes associated with the act of autotomy included a bradycardia and/or associated cardiac pausing before the chela was shed, followed by a subsequent increase in cardiac parameters. Changes in the cardiovascular physiology were paralleled by an increase in oxygen uptake, which was driven by an increased ventilation of the branchial chambers. Although limb loss is a major event, it appears that only acute changes in physiology occur. These may benefit the individual, allowing rapid escape following autotomy with a subsequent return to normal activity.     

Densitometry from digitized images of X-radiographs: Methodology for measurement of coral skeletal density

Skeletons of massive coral colonies contain annual density bands that are revealed by X-radiography of slices cut along growth axes. These bands allow measurement of skeletal growth parameters such as annual extension rate and annual calcification rate. Such measurements have been important in understanding coral growth, in assessing environmental impacts and in recovering proxy environmental information. Measurements of coral calcification rate from annual density banding require measurements of skeletal density along tracks across skeletal slices and, until now, such density measurements have depended upon specialized and expensive equipment. Here, we describe a straightforward, inexpensive and accurate technique for measuring skeletal density from digitized images of X-radiographs of coral skeletal slices. An aragonitic step-wedge was included in each X-radiograph of a coral slice together with two aluminium bars positioned along the anode-cathode axis. Optical density was measured along tracks across the X-ray images of these different objects. The aragonite step-wedge provided a standard for converting optical density to skeletal density. The aluminium bars were used to correct for the heel effect—a variation in the intensity of the X-ray beam along the anode-cathode axis that would, otherwise, introduce large errors into measurements of skeletal density. Exposure was found to vary from X-radiographs to X-radiograph, necessitating the inclusion of the calibration standards in each X-radiograph of a coral slice. Results obtained using this technique compared well with results obtained by direct gamma densitometry of skeletal slices.     

Diet and feeding habits of predatory fishes upstream and downstream of a low-level weir

A study investigating the influence of a low-level weir on the diets of three migratory percithyid species was undertaken on the Murrumbidgee River, Australia. A combination of fish community sampling and stomach flushing determined that Yanco Weir substantially impacted upon the abundance and feeding habits of golden perch Macquaria ambigua , Murray cod Maccullochella peelii peelii and trout cod Maccullochella macquariensis . The relative abundance of all three species was significantly greater downstream of the weir, where individuals attempting upstream migrations were obstructed. In areas of fish aggregations, some species displayed altered feeding strategies and exploited different prey taxa upstream and downstream of the weir. Diet overlap, and the proportion of individuals with empty stomachs, was also substantially greater from downstream zones. These results suggest that competition among species may be greater in areas of increased predator abundance and some species could be partitioning resources to minimize competitive interactions. Reducing accumulations of predatory species, by providing suitable fish passage facilities, would be an effective means to prevent such trophic interactions occurring at other low-level weirs.     

Geographical variation in the potential of mice to constrain an ant-seed dispersal mutualism

Pre‐ and post‐dispersal Helleborus foetidus (Ranunculaceae) seed predation by mice Apodemus sylvaticus as well as post‐dispersal seed removal by ants was studied, during two years, in six plant populations within three geographical regions (Caurel, Cazorla and Mágina) of the Iberian Peninsula. An observational approach revealed strong interregional differences in seed predation by mice during the pre‐dispersal phase, with high and similar rates of predation in Cazorla and Mágina and much lower rates in Caurel. There were also significant inter‐annual variations on pre‐dispersal seed predation by mice, while the existing habitat‐related differences (of lower magnitude) were not consistent across regions. Field experiments based on seed‐offering exclosures, showed that, despite some interregional variation, post‐dispersal seed removal by ants was consistently high through all spatial and temporal scales considered, with most seeds being removed within 48 h. Conversely, post‐dispersal seed predation by mice was highly variable among regions, being very high in Cazorla and minimal or absent in Caurel and Mágina. Interestingly, in Cazorla, in presence of mice, the number of seeds removed was rather independent of the presence/absence of ants, while under mice exclusion, it was determined by the presence/absence of ants. Conversely, in Caurel, the number of seeds removed by each remover agent (ants or mice) was independent of the presence/absence of the other agent. Thus, though uniquely in Cazorla, mice limited the number of seeds available to ants and, therefore, in this region could potentially have interfered on the development of seed traits that enable ants to efficiently harvest them. Our results support the notion that geographical variation over the Iberian Peninsula of mice seed predation may have promoted a mosaic of well‐matching and mismatching situations between H. foetidus diaspore traits and the characteristics of ant communities, which is consistent with some recent theories on the geographical structure of interactions.     

The first record of Misgurnus anguillicaudatus in Germany

Oriental weatherfish Misgurnus anguillicaudatus , from southern China, have been imported to Germany in large numbers for the garden pond trade. The first record of M. anguillicaudatus from Central Europe, a population that has been established for at least 14 years in a small nature reserve in Germany, is detailed.     

The incidence of the parasitic disease trichomoniasis and its treatment in reintroduced and wild Pink Pigeons Columba mayeri

The recovery programme for the endangered Pink Pigeon Columba mayeri Prévost, 1843 of Mauritius has involved intensive management to promote rapid population growth. As the Pink Pigeon population has increased in size and distribution, disease problems have emerged that have affected wild and reintroduced birds. Trichomoniasis first appeared in the remnant wild population in 1992, and became established in a reintroduced subpopulation on the offshore island of Ile aux Aigrettes. We aimed to control the disease by treating individuals and, on Ile aux Aigrettes, by routinely treating the population with medicated drinking water. On Ile aux Aigrettes, 49% of squabs were clinically diseased and only 27% of all squabs survived without treatment. Treatment of squabs that were not clinically diseased improved survival from 36 to 82%, suggesting that subclinical infections also affected survival. Subclinical infections were demonstrated by microscopy in 22% of Pink Pigeons and 17% of exotic doves on Ile aux Aigrettes. Clinical disease was observed in 4.5% of adults and 3.1% of juveniles, but more juveniles than adults died from the disease. It is likely that Trichomoniasis and other diseases will continue to affect the Pink Pigeon's recovery and the species may require long-term management to counteract the effects of disease and other limiting factors.     

The urticating setae of Ochrogaster lunifer,an Australian processionary caterpillar of veterinary importance

The bag‐shelter moth, Ochrogaster lunifer Herrich‐Schaffer (Lepidoptera: Notodontidae), is associated with a condition called equine amnionitis and fetal loss (EAFL) on horse farms in Australia. Setal fragments from O. lunifer larvae have been identified in the placentas of experimentally aborted fetuses and their dams, and in clinical abortions. The gregarious larvae build silken nests in which large numbers cohabit over spring, summer and autumn. The final instars disperse to pupation sites in the ground where they overwinter. Field‐collected O. lunifer larvae, their nests and nearby soil were examined using light and electron microscopy to identify setae likely to cause EAFL and to determine where and how many were present. Microtrichia, barbed hairs and true setae were found on the exoskeletons of the larvae. True setae matching the majority of setal fragments described from equine tissue were found on third to eighth instar larvae or exuviae. The number of true setae increased with the age of the larva; eighth instars carried around 2.0–2.5 million true setae. The exuvia of the pre‐pupal instar was incorporated into the pupal chamber. The major sources of setae are likely to be nests, dispersing pre‐pupal larvae and their exuviae, and pupal chambers.