Community and network ecology of biting Diptera-host interactions

Keywords: blood meal
zoology
ecological network
Culicidae
metabarcoding
biting Diptera
mosquito
ecology

Biting flies (Diptera) are responsible for the transmission of a wide range of pathogens that infect humans and animals. Biting Diptera are highly taxonomically and ecologically diverse and display a range of blood-feeding behaviours. Most species are generalist and have the potential to take blood meals from hosts of different species through opportunistic feeding. However, some Diptera species also display a consistent host preference at the class or species level. These patterns of host use are not thoroughly documented and have important implications for the transmission of disease within and between host species, and pathways for the emergence and spread of current and novel diseases. Interactions between Diptera and their hosts can now be reliably identified using DNA barcoding and metabarcoding of Diptera blood meals. However, most biting Diptera research has focused on individual species and their interactions with specific hosts. In this thesis I investigate the community and network ecology of biting Diptera – host interactions. First, using a database of Diptera-host interactions compiled from the literature, I highlight the potential insights that can emerge from using ecological interaction networks to examine biting Diptera community composition, interaction structure, and associated disease transmission risks, and how these can change in response to perturbations. Using the same dataset, I then applied a network approach to investigate the effects of macroecological and local anthropogenic factors on biting Diptera-host network structure. I found that the evenness of biting Diptera-host interactions was higher in Village/Urban habitats, but evenness or the overall specialism of the biting Diptera-host networks did not vary on a global scale with latitude. Interaction networks should be populated with the most complete data possible. In compiling my interaction database, I found a gap in the current understanding of how the degradation of host DNA in blood meals as a result of digestion and storage conditions reduces blood meal identification success. I investigated the effect of digestion time and storage condition on the identification success of biting midge blood meals. I found that increased blood meal digestion time, but not the storage condition, reduced the success of host identification. Finally, using biting Diptera collected in Ghana, I examined empirically the effect of anthropogenic landscape modification on biting Diptera community composition and structure. Biting Diptera community composition differed little across an anthropogenic landscape modification gradient, indicating a shared community. In addition, network structure differed across different levels of habitat modification. I then identified interactions between Diptera competent of vectoring a range of pathogens and susceptible hosts, which may have the potential to act as disease transmission events. The findings reported in this thesis highlight the potential application of ecological networks to research on biting Diptera and provide new insights into the impact of anthropogenic landscape modification on biting Diptera-host community and interaction structure.