Mosquitoes are found in extremely large numbers in the lower parts of the River Dalälven. In the year 2000 the Mosquito nuisance was especially high, resulting in foundation of the Biological Mosquito control project. Since 2001 Mosquito larvae are controlled by using a biological pesticide BTI (Bacillus thuringiensis ssp israelensis). The Mosquito fauna in the area is dominated by flood water Mosquitoes, a group of Mosquitoes that are very aggressive and form new generations of Mosquitoes during every single flooding event during the summer. To be able to efficiently control the Mosquitoes it is essential to know the extension and locality of the flooding.

Francisella tularensis, the causative agent of the zoonotic disease tularaemia, is highly contagious and potentially fatal for a wide range of wildlife species of the northern hemisphere, also humans. Although recognized as a pathogen for over 100 years, much still remains to be elucidated concerning the ecology and transmission of the bacterium, hence this literature overview aims at compiling data regarding the aquatic association and the role of Mosquitoes in transmission of Francisella tularensis subspecies holartica, the sole subspecies in Sweden. While a linkage between the bacterium and natural waters stands beyond dispute, there is no consensus in the literature concerning its potential as a reservoir. However, two prevailing theories can be distinguished; one proposes the water association being mammaldependent and thus merely the result of contamination from semi-aquatic mammals living in close vicinity to the water source. The other, quite contrary, suggests mammal-independence and hence that water, possibly in association with protozoa, serves as an environmental reservoir for the bacterium.

Japanese encephalitis virus (JEV) is a significant vector-borne zoonotic pathogen, causing devastating encephalitis in humans. Its geographical range includes a majority of Asian countries and has also been recognized in some western Pacific areas. The main vectors of JEV are Mosquitoes belonging to the genus Culex. Birds and pigs function as hosts and virus amplifiers, whereas humans are accidental hosts. Japanese encephalitis is commonly regarded as a rural disease.

Rift Valley Fever (RVF) is a disease caused by Rift Valley Fever virus (RVFV), which is an arbovirus. An arbovirus is a virus that is transmitted by an arthropod vector, in this case a Mosquito. The virus is a member of the Phlebovirus genus in the family Bunyaviridae. It was first identified in the Rift Valley in Kenya in 1930. The disease is a zoonosis but mainly affects domestic ruminants inducing massive abortions and a high mortality among young animals.

The virus-mediated disease Rift Valley fever (RVF) was discovered during an outbreak in Kenya in the 1930s. Since then it has spread to most parts of Sub-Saharan Africa, and in the last decades several outbreaks have caused economic and health issues in Africa, Yemen and Saudi-Arabia. The disease mainly affects domestic livestock, causing abortions, but is also a zoonosis. To be able to control the spread of the disease it is important with surveillance for better knowledge about the distribution and virus circulation even in inter-epidemic/epizootic periods. The human population is growing, and people and their livestock constantly move closer to areas with wild animals which act as reservoirs for different viruses. Also, humans and their animals often get within reach for arthropod vectors, hosting or carrying viruses.