Effects of mosquito resting site temperatures on the estimation of pathogen development rates in near-natural habitats in Germany

Abstract

Background Environmental temperature is a key driver for the transmission risk of mosquito-borne pathogens. Epidemiological models usually relate to temperature data from standardized weather stations, but these data may not capture the relevant scale where mosquitoes experience environmental temperatures. As mosquitoes are assumed to spend most of their lifetime in resting sites, we analysed mosquito resting site patterns and the associated temperatures in dependence on the resting site type, resting site height and the surrounding land use. Methods The study was conducted in 20 areas in near-natural habitats in Germany. Ten areas were studied in 2017, and another 10 in 2018. Each study area consisted of three sampling sites, where we collected mosquitoes and microclimatic data in artificial (= garden pop-up bags) and natural resting sites at three height levels between 0 and 6 m. Land use of the study sites was characterized as forest and meadows based on reclassified information of the CORINE (Coordination of Information on the Environment) Land Cover categories. The hourly resting site temperatures and the data from the nearest weather station of the German meteorological service were used to model the duration of the extrinsic incubation period (EIP) of mosquito-borne pathogens. Results Anopheles, Culex and Culiseta preferred artificial resting sites, while Aedes were predominantly collect in natural resting sites. Around 90% of the mosquitoes were collected from resting sites below 2 m. The mosquito species composition did not differ significantly between forest and meadow sites. Mean resting site temperatures near the ground were approximately 0.8 °C lower than at a height of 4–6 m, which changed the predicted mean EIP up to 5 days at meadow and 2 days at forest sites. Compared with temperature data from standardized weather stations, the resting site temperatures near the ground would prolong the mean estimated EIP 4 days at forest sites and 2 days at meadow sites. Conclusions The microclimate of mosquito resting sites differs from standardized meteorological data, which can influence the transmission of mosquito-borne pathogens. In a near-natural environment, colder temperatures at mosquitoes’ preferred resting sites near the ground would prolong the EIP of mosquito-borne pathogens relative to data from weather stations. Graphical Abstract

Effects of Temperature on Blood Feeding and Activity Levels in the Tiger Mosquito, Aedes albopictus

“…Dispersing to a more favorable microhabitat can be an effective tactic for reducing heat stress, as temperatures across microhabitats can vary tremendously and act as a buffer [ 65 , 66 , 67 , 68 ]. For instance, many insects will move towards shaded or cooler habitats towards the soil, which allow them to survive in an otherwise lethal environment [ 60 , 65 , 67 , 69 ]. Mosquitoes will commonly rest in well-shaded crevices of earth banks, stones and trees, or within vegetation or human structures as a refuge [ 61 ] (pp.…”

“…316–317). Adult mosquitoes of the genus Aedes most frequently rest in vegetation closer to the ground and in the shade and avoid resting sites with temperatures above 30 °C [ 69 , 70 , 71 ], all of which are behavioral thermoregulatory mechanisms.…”