Master Thesis

The importance of habitat structure and environmental variables for the distribution, abundance, and composition of mosquito larvae within the Donaumoos, Bavaria

Maria Umlauf (06/2022-12/2022)

Support: Stephanie Thomas, Carl Beierkuhnlein, Ellen Kiel

Global change causes temperatures to rise and extreme events such as droughts to occur more frequently and intensely. These changes have caused concern, as they are often believed to be associated to higher mosquito abundances and in consequence more frequent outbreaks of mosquito-borne diseases. In addition to climate change mitigation methods such as the rewetting of peat bogs for instance, mosquito populations might undergo significant changes in their distribution, abundance, and composition. Understanding mosquito populations and their drivers is the key to a successful management strategy upon the occurrence of mosquito-borne diseases. This study investigated the larval populations of mosquitoes within the Donaumoos, a drained peat bog in Bavaria. Amidst drought conditions, only 33 larvae were found, belonging to the species Anopheles maculipennis (n = 28), Anopheles messeae (n = 2), Anopheles claviger (n = 1) and to the genus Culex (n = 2). Highest counts were found in agricultural areas (n = 23) and amongst emergent vegetation (n = 24), especially grasses (n = 24). Anopheline larvae dominated over culicines in most land uses and habitats, except vegetated areas and habitats characterized by floating vegetation, which presented on culicine larvae and zero anopheline larvae. Area coverage of the respective sub-habitat was positively associated with anopheline larval abundances, while water turbidity was negatively associated with anopheline abundances. The low abundances of mosquito larvae can be both explained by drought conditions over throughout 2022, as well as the presence of Gammarus spp. (n = 1407), of which some species are known to feed on mosquito larvae.