Bats in an Afrotropical agricultural landscape: foraging ecology and implications for insect pest control services

Abstract

Overwhelming evidence of detrimental impacts of anthropogenic activity on the environments in which we live, has instigated global efforts to curb the biodiversity and climate change crises. One such activity is agriculture, which serves to illustrate the clash between meeting the needs of growing human populations, and addressing these crises. The role that biodiversity plays in the provision of ecosystem services in agriculture, needs to be considered for production to be sustainable in the long term. As such, we need to understand the ecological functions and requirements of species assemblages in agricultural landscapes, to design and implement conservation management strategies. Insectivorous bats have been shown to suppress insect populations, including crop pests, to an extent that can constitute an insect pest regulation service. However, such research has lagged behind in the Afrotropical region, with only a handful of studies investigating the pest regulating contributions made by bats as natural predators. This PhD project set out to build on the understanding of species assemblages, habitat use and insect predation by bats in the agroecological context in an Afrotropical commercial agricultural landscape. Firstly it addresses one limitation to the use of bioacoustics methodology to study bats in the region, by presenting the first acoustic call library of its scale for Zambia, an Afrotropical country in the ecological transition zone between southern and central African habitats, where many bat species ranges cross country borders. Secondly, bioacoustic methods were used to study the foraging activity of functional groups of bats utilising commercial agricultural landscapes in Zambia, and to explore local and landscape scale factors that may influence this. Functional groups recorded acoustically in these agricultural landscapes, responded differently to woodland cover within the local habitat and across the landscape. Thirdly, molecular methods were employed to explore diet to build understanding of the relationships between bat predators and their insect prey in these agricultural habitats. Consumption of insect pests was a confirmed and results demonstrate the importance of maintaining populations of multiple functional groups in species assemblages, which aids in the regulation of the range of insect orders and suppress crop pests present. Finally, potential prey abundance in different crops was determined. Bat foraging activity did not differ between maize, soya and tobacco crops, and this was supported by the finding that potential prey taxon abundance was similar in these crops. The combined results of this thesis lay the foundations for research into the role that bats play in commercial agricultural landscapes in this Afrotropical context. In addition to considering functional groups, future studies should conduct species-specific research, and should go into further detail exploring the ecology and behaviour of bats in these agricultural landscapes by taking advantage of advances in bioacoustic, genetic and telemetry technology. By gaining a better general understanding of this understudied group of mammals, on the understudied African continent will be of great benefit to both bats and people.