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Understanding the role of subterranean ants in maintaining healthy soils for agroecosystems

Primary Supervisor: Dr Heather Campbell, Crop and Environmental Sciences

Secondary supervisor: Dr Simon Segar or Dr Simon Jeffrey

External collaborator: Caswell Munyai

PhD project title: Understanding the role of subterranean ants in maintaining healthy soils for agroecosystems

University of Registration: Harper Adams University

Global impacts on biodiversity and ecosystem services are driven primarily by habitat loss and degradation as a result of deforestation and conversion to agricultural land use. Modification of natural systems leads to changes in above and below ground biodiversity, which may then impact the function and stability of the transformed agroecosystems. Soil is an essential component of sustainable ecosystems, but below-ground diversity is less well-studied than the equivalent above-ground organisms. Such is the importance of soil health that the Intergovernmental Platform on Biodiversity and Ecosystem Services have now incorporated it into their regional assessments of biodiversity.

Ants fulfil a range of functions in natural and agricultural systems, including nutrient cycling, seed dispersal and pest control. Additionally, they are abundant in soil communities where they play an important role in soil aggregation and aeration; mineralization of litter and organic residues; and modifying soil chemistry through changes in PH and microbial activity. It has been suggested that ants could be a potential candidate as bioindicators of soil-based ecosystem services, but this requires a better understanding of subterranean ant diversity and their specific roles in soil ecology. In cool, wet systems of temperate regions earthworms are considered to be the main soil ecosystem engineers. However, the majority of future agricultural intensification will take place in tropical and subtropical regions of the world. In these drier and hotter habitats ants and termites replace earthworms as the main driver of soil health, with one study demonstrating their presence led to a 36% increase in wheat yield.

Subterranean ants – those living and foraging below ground – have been referred to as the “final frontier” in the study of ant biodiversity. This project will examine multiple soil taxa but primarily aims to explore methods for sampling subterranean ant diversity, identifying the functional and trophic role of these ants and then assessing their contribution to ecosystem function in forestry or agricultural systems. Depending on the interests of the student the project may be tailored to include more field or lab-based methods incorporating a combination of traditional biodiversity sampling, experimental field-scale experiments, DNA barcoding, and DNA-gut-content or stable isotope analysis. The role of ants in soils is limited by the ability of scientists to study below-ground diversity and interactions. Currently, baited subterranean traps are used to collect specimens, followed by a lengthy process of morphological identification of species. Identification requires a high level of expertise and is hampered by the small size and cryptic morphology of subterranean ants. The project will aim to optimise molecular methods for identifying specimens in order to provide a rapid method for characterising soil ant communities. Following this, lab or field-based approaches, including microcosm experiments, will be used to understand the functional role and ecosystem provision of services by ants in soils. In particular their trophic interactions will be characterised. Ultimately, field-scale experiments will be used to study the contribution of ants to soil ecosystem services in crop systems. Given the importance of subterranean ants in tropical systems there may be opportunities to conduct fieldwork in either coffee agroforestry systems in Mozambique or in agricultural or forest plantation systems in South Africa. Applicants should have a broad interest in ecology, preferably with some experience in entomology.

References:

  1. Sanabria, C. et al. (2014) Ants as indicators of soil-based ecosystem services in agroecosystems of the Colombian Llanos. Applied Soil Ecology 84, 24-30.
  2. Evans, T.A. et al. (2011) Ants and termites increase crop yield in a dry climate. Nature Communications 2, 262-262.
  3. Janion-Scheepers, C. et al. (2016) Soil biota in a megadiverse country: Current knowledge and future research directions in South Africa. Pedobiologia 59 (3), 129-174.

BBSRC Strategic Research Priority: Sustainable Agriculture and Food: Plant and Crop Science

Contact: Dr Heather Campbell, Harper Adams University