Applied & Behavioural Ecology
Dr Ian C.W. Hardy
Dr Helen M. West
Our ecological studies span from individuals, through populations to communities and (agro-)ecosystems. At the level of the individual, we work to improve the functional understanding of behaviour. One of the most important components of an individual’s environment is the presence of other individuals. We study direct interactions (both behavioural and chemical) between competing individuals, such as fighting and dominance, and also mating interactions between males and females. We also study the consequences of mating and contest behaviour on the subsequent reproductive decisions of females, chiefly in terms of the number of sexes of offspring they produce. These behavioural decisions have further consequences at the population level and also for the composition of ecological communities. Research at these levels is chiefly applied to improving the performance of parasitoid wasps as agents of biological pest control and to conserving a number of species of large birds of prey and scavengers in southern Africa. The effects of veterinary residues on non-target insects are also pertinent to individual and community levels, and are of wide interest given the global use of these products. Understanding the lethal and sub-lethal effects of veterinary drugs in relation to farm management practices will provide farmers with information on which to base management decisions.
General Research Themes include:
• Behavioural Ecology: Contest behaviour, sex ratio and mating systems, clutch size decisions, social behaviour.
• Biological Pest Control: Biological control consequences of intra- and interspecific interactions between parasitoid wasps.
• Bird Conservation Ecology: Biology and ecology of African vultures, African Crowned Eagles and Marabou storks.
• Dung Ecology: Ecological and physiological effects of veterinary pharmaceuticals on non-target insects.
Contest and mating behaviour
Much of the empirical work on contest behaviour includes the identification of factors determining contest outcome in Bethylid wasps, particularly in the genus Goniozus. We have found that Goniozus females often emit volatile chemicals during contests. Such chemical emissions have been revealed (and chemically identified) using a mass spectrometer modified for direct analysis of volatiles in the gas phase, giving a time course profile of volatile release. This methodology is novel to the study of animal behaviour. We have also devised and pioneered a technique for chemically marking contestants using deuterium: coupled with real-time analysis this has shown that, without exception, it is the loser of a contest bout that emits the chemical. We are now using these techniques to assess chemical release behaviour during courtship, and rejection, interactions in further species of parasitoid wasps.
Biological Control Applications
Insect parasitoids are important natural enemies of agricultural pests. We use the understanding obtained from behavioural ecological studies to evaluate and improve the biocontrol potential of a number of parasitic wasp species. For instance, we have investigated interspecific behavioural and trophic interactions between three parasitoids from the same taxonomic family that are natural enemies of the same host species. This has shown that females aggressively contest paralyzed hosts and the loser is often killed in inter-specific but not intra-specific contests. This highlights the need to determine how many, and which, natural enemy species should ideally be present in agro-ecosystems.
Conservation ecology of birds of prey and scavengers
Working with the University of Swaziland we are studying various aspects of the biology and ecolog y of large scavenging and predatory birds across southern Africa. The work ranges from the development and evaluation of trapping methods, through behavioural studies to regional and trans-continental analyses of habitat use and generic evaluations of habitat selection modelling. The species under study are several species of vultures, marabou storks and the African Crowned Eagle. For instance, using statistical modelling, we have shown which factors affect nest site preferences in African White-backed vultures (human disturbance is a major negative influence). We have further shown that such habitat selection models are not transferrable between regions. Models can be constructed using multiple-region data but these then perform less well in any given region.
Monitoring Farm and Regional Scale Effects of Anthelmintics and Endectocides
Routine use of worming drugs may cause problems for non-target invertebrate species living in cattle dung, particularly in intensively managed grasslands. We are surveying ~80 farms in central England to evaluate veterinary drug use and monitor biodiversity of dung inhabitants. The outcomes of this project (funded by the Esmée Fairbairn Foundation) will include an update of patterns of drug use on farms, data sets of coprophilous insect abundance, a model to evaluate the risks of drug use and a computer-based decision aid aimed at the farming industry and conservationists. Collaborators are Sarah Martin, Neil Crout and Paul Wilson, University of Nottingham.
Sub-lethal Effects of Endectocides on Dung-flies
Most studies of the effects of cattle worming drugs on non-target insects focus on presence or absence from cow pats (i.e. insect survival), but effects may also be sub-lethal. We are investigating whether immunity of the non-target insect Scathophaga stercoraria is enhanced by use of veterinary pharmaceuticals. Preliminary work showed that egg-to-adult exposure to extremely low (and environmentally relevant) concentrations of ivermectin elevated activity of the enzyme phenoloxidase (a measure of potential immunity) in yellow dung flies. The aims of the project are to establish whether an increase in phenoloxidase enhances survival against microbial challenge and to determine the energetic costs of maintaining an ivermectin-related up-regulated immune response. The project is in collaboration with Dr Penny R Hirsch (Rothamsted Research) and is funded by the Lawes Trust.