Determination of the toxic effects of some herbicides used in paddy agriculture on Aedes aegypti and Culex pipiens mosquito species

Mosquitoes (Culicidae) are creatures with high adaptability to different ecological conditions, which are distributed in almost every region of the world except the poles. Due to the diseases they vector both in public health and veterinary field, an intensive fight against mosquitoes is carried out. Among the insecticide groups used in the control of mosquitoes, synthetic pyrethroids, neonicotinoids and carbamates are generally preferred. Although these products are very effective in many parts of the world, the resistance detected in mosquitoes makes it difficult to suppress populations in some regions. In addition, these insecticides can adversely affect the environment and human health. Agricultural products are used to meet the basic needs of humans and animals such as clothing, nutrition and shelter, and high amounts of pesticides are used in their production. Agricultural areas can be environments where many creatures can live together due to the habitat diversity they have. The areas where paddy (rice) plants, which meet the nutritional needs of more than 50% of the world's population, are grown also offer favorable environments for the life of many vertebrates and invertebrates. Different pesticide groups are used against pests in paddy cultivation. Especially the consumption of herbicides used for weed control is quite high. The fact that the areas where paddy is grown are aquatic environments allows these areas to be used by mosquitoes as a development environment. Mosquitoes developing in paddy fields where larval development occurs are exposed to the pesticides used. The aim of this thesis was to investigate the toxic effects of different application doses of bentazone+MCPA, bispyribac sodium, cyhalofop butyl, quinclorac, oxadiazon and clomazone herbicides on the larvae of Culex pipiens and Aedes aegypti mosquitoes which are important for public health. The toxic effects of herbicide doses were investigated in the laboratory on early (1-2) and late (3-4) larval stages of each mosquito population. To determine the toxic effects of herbicides on mosquitoes, larval mortality, larval to pupal transition rates and pupal to adult rates were recorded daily throughout the exposure period. The data obtained were analyzed in SPSS statistical analysis program. According to the application doses tested, oxadiazon was found to be more toxic to mosquitoes than other herbicides in all populations and stages of both mosquito species and mortality rates increased as the application dose of oxadiazon increased. For other herbicides, the toxic effect was low. In addition, early stage larvae were found to be more susceptible to herbicides. The results indicate that some herbicides applied in paddy growing areas may be toxic to mosquitoes developing in this environment.