Barbara Hart

Habitat use by wood mice ( Apodemus sylvaticus ) in a changeable arable landscape

Wood mice Apodemus sylvaticus are potentially useful indicators of change in arable ecosystems. Here we focus on changes resulting from removal of land from arable production under the set-aside scheme. Wood mice were radio-tracked to compare: (a) their use of set-aside, crop and hedgerow before and after harvest; (b) set-aside configured as margins and as a 3 ha block; (c) cut and uncut 20-m wide set-aside margins. Males had larger home ranges, and were more mobile than females. Ranges were larger, and animals more mobile, before harvest than afterwards. There were no differences in range sizes of breeding and non-breeding animals after harvest, suggesting that changes in habitat use were not a function of cessation of breeding. Before harvest, wood mice used habitats within their ranges at random, and their ranges contained a high proportion of cropped area. After harvest they preferred hedgerow and avoided margin set-aside within their ranges, but did not similarly avoid the set-aside block. The proportion of cropped area within their ranges decreased after harvest, and the proportion of margin increased. Our evidence suggests wood mice avoided using the area adjacent to the hedgerow, perhaps to avoid predators. Uncut set-aside patches were favoured and cut patches avoided, possibly in response to differences in food availability and levels of protection from predators. These results confirm that wood mice are useful indicators of change in arable landscapes.

Managing set-aside for field voles (Microtus agrestis)

Abstract Set-aside is a potentially important habitat for field voles, ( Microtus agrestis ), populations of which may have declined in lowland Britain. We hypothesized that field vole abundance would increase with the length of time set-aside was left in situ. To test this we monitored development of field vole populations in the first 2 years after set-aside establishment, and on older set-aside we related abundance to set-aside age and vegetative characteristics. Voles were not recorded on set-aside until 9 months after establishment, and populations only began to increase after nearly 2 years. In set-aside fields 2–9 years old, vole abundances were not related to age, but increased with the proportion of grasses and litter in the sward. Management practices such as sowing with a grass seed mix, mowing at least once annually and leaving set-aside in place for >2 years are likely to benefit field voles.

Reproduction and Development of Laboratory and Wild House Dust Mites (Acari: Pyroglyphidae) and Their Relationship to the Natural Dust Ecosystem

Abstract Life histories of “wild” house dust mites, Dermatophagoides pteronyssinus (Trouessart) (Acari: Pyroglyphidae), were compared with laboratory cultures by using a diet consisting of skin and dust or a laboratory diet consisting of dried liver and yeast. Under constant conditions of 25°C and 75% RH, fecundity and rate of reproduction were higher in laboratory cultures on both diets compared with wild mites. There were also trends for a shorter prereproductive period and more rapid egg development of laboratory mites compared with wild mites. Overall, there was little effect of diet on either strain of mites at 75% RH. At low RH (64%), fecundity was significantly lower (for both strains on both diets), and there were also trends for longer prereproductive period, reduced rate of reproduction, reduced adult survival, prolonged egg and juvenile development, or a combination compared with 75% RH. Additionally egg and juvenile mortality were significantly higher on the liver and yeast diet. Overall, the skin and dust diet favored both strains of mites at 64% RH. On the liver and yeast diet at 64% RH, wild mite adults performed significantly better than laboratory mites, and egg mortality was lower. These results suggest that laboratory mites have stronger reproduction and development than wild mites, except when under environmental stress and that diet is a significant factor, particularly in suboptimal conditions. This could have important implications for predictive models of house dust mite populations in their natural habitat. Ideally, such models should be developed using data from wild dust mite populations reared on a natural diet.

Application of a transient hygrothermal population model for house dust mites in beds: assessment of control strategies in UK buildings

This article discusses the capabilities and the application of an innovative combined hygrothermal and population model to assess the impact of building design and occupant behaviour on house dust mite populations in a mattress. The combined model is the first of its kind able to predict the impact of hourly transient hygrothermal conditions within a 3-dimensional mattress on a population of ‘wild’ Dermatophagoides pteronyssinus mites. The modelling shows that the current drive for energy efficiency in buildings might lead to an increase in house dust mite infestations in UK dwellings. Further research is needed to accurately determine the size of these effects and to adequately evaluate any trade-offs between energy efficiency measures and health outcomes.

The biology of allergenic domestic mites : an update

ConclusionSince 1990 our knowledge of the biology of domestic mites has increased in a number of areas. Taxonomically, keys that are easier to use by nonacarologists have been made available and should help in clinical studies of mite populations in the home environment. From house dust surveys our understanding of the geographical distribution ofE. maynei andB. tropicalis has progressed. Detailed studies of mite populations in mattresses has clarified the distribution of mites within this habitat, which may eventually aid in targeting control of mites in mattresses. In relation to this, a clearer understanding of the influence of climatic factors on the mattress microhabitat has led to investigations into the potential use of ventilation as a means of domestic mite control. Our increased understanding of the survival of desiccation resistant protonymphs is important in this regard. More information on the biochemistry of mite enzymes has been obtained from studies to characterize potentially allergenic mite enzymes. Finally, the relationship between house dust mites and fungi has been resolved with respect to both nutritional ecology and allergen production. Our progress in all of these areas serves to demonstrate the invaluable contribution that biological research can make to clinical studies of domestic mite epidemiology, allergen production, and control.

How can field margin management contribute to invertebrate biodiversity

Farmland invertebrates are vital for healthy ecosystem functioning. Many groups have declined due to agricultural intensification. Arable field margins potentially can increase food resources and provide winter refuges for invertebrates. They might also buffer them from agrochemical applications and farm operations. This chapter describes a series of field and farm-scale experiments which show that ways in which arable field margins are established and managed can have profound effects on their invertebrate assemblages. Field margin swards established by sowing with a grass and wildflower seed mixture attracted more butterflies than naturally regenerated swards. In the short term, larger and more species-rich invertebrate assemblages were fostered on unmanaged margins than on those managed by cutting. The timing of cutting was critical, with mid-summer cutting having the most persistent, negative effects on invertebrates, while cutting in spring and autumn was generally less damaging and may help maintain sward species richness. Fallowed land (set-aside) configured as blocks rather than margins constituted qualitatively different habitats for invertebrates. Margin width had complex effects on invertebrate abundance and species richness. Boundary hedgerows increased numbers of most invertebrate groups in the adjacent margin. The chapter suggests that blanket management approaches for invertebrates at the farm scale are not optimal. A diverse farmed landscape, with margins of different sizes and different sward structures, will provide for the different ecological requirements of invertebrate populations, and promote their diversity in the characteristically unstable environment of arable systems.

The psychrometric control of house dust mites: a pilot study

This paper describes a pilot intervention study on the effectiveness of house dust mite allergen avoidance for 12 asthmatic children (two being controls). In addition to mite allergen removal, the study included tailored advice aimed at reducing mite population growth via changes in moisture production, heating and ventilation habits. This paper focuses on the effects of this advice on household behaviour, hygrothermal conditions and mite populations. The efficacy of monitoring and modelling techniques is also discussed. The study highlighted a number of interrelated confounding factors which have to be addressed in future similar larger scale studies, but the results are promising with regards to the effectiveness of such studies. Practical application: This study suggests that in temperate climates tailored advice on moisture production, heating and ventilation habits can lead to valuable changes in hygrothermal conditions, which in turn can result in reduced mite populations. However, pre-existing adverse building conditions may hinder such changes, and the effectiveness of tailored advice and of hygrothermal modifications is often difficult to assess. It is therefore recommended that any similar larger intervention study measures ventilation rates and adequately controls for a number of confounding variables — including the effect of changes in outdoor conditions and of the removal of existing mite populations. In this respect, hygrothermal population models can play a very useful role in the assessment of study effectiveness.