Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission

Authors: FOTAKIS, M - UNIVERSITY OF GREECE - CRETE; CHASKOPOULOU, ALEXANDRA - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); GRIGORAKI, L - UNIVERSITY OF GREECE - CRETE; TSIAMANTAS, A - AGRICULTURAL UNIVERSITY OF ATHENS; KOUNADI, S - UNIVERSITY OF GREECE - CRETE; GEORGIOU, L - GENERAL DIRECTORATE OF PUBLIC HEALTH, REGION OF EASTERN MACEDONIA AND THRACE; VONTAS, J - AGRICULTURAL UNIVERSITY OF ATHENS

Submitted to: ACTA TROPICA
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2017
Publication Date: 6/6/2017
Citation: Fotakis, M., Chaskopoulou, A., Grigoraki, L., Tsiamantas, A., Kounadi, S., Georgiou, L., Vontas, J. 2017. Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission. ACTA TROPICA. 174:29-37. doi: 10.1016/j.actatropica.2017.06.005.

Interpretive Summary: Mosquitoes are an important pest of humans that are annoying and that transmit serious diseases. They pose a serious and increasing problem in Greece, which is aggravated by an influx of immigrants, a weak economy and significant tourist industry. The West Nile Virus (WNV) outbreak in Thessaloniki in 2010 foreshadows problems likely to occur in other regions. The broad objective of this study was to increase our understanding on the ecology of important mosquito vectors and the mechanisms of insecticide resistance. Specifically through this work we aimed to a) identify the mosquito species, and determine their seasonal abundance, and b) measure the level of resistance to insecticides of the major species, and determine the underlying mechanisms of resistance (genetic target site, metabolic resistance). We concluded that mosquito surveillance programs including species identification, population dynamics and resistance analysis is essential for guiding sustainable and efficient mosquito control strategies. Furthermore, with pyrethroids being the most dominant group of insecticides in both vector control and agriculture, it is increasingly important to invest in development of new insecticidal groups with novel modes of action that will help to expand the currently very limited vector control toolbox.

Technical Abstract: Greece has been recently affected by several mosquito borne diseases, with the West Nile Virus (WNV) outbreak in 2010 being one of the largest reported in Europe. Currently at the epicenter of an economic and refugee crisis, and as a country which is visited by over 16 million tourists a year, the integrated management of diseases transmitted by mosquitoes is a public health and economic priority. Vector control programs rely mainly on insecticides but a major problem hindering their effectiveness is the development of insecticide resistance. In Greece, data on insecticide resistance and the mosquito fauna present in areas of interest is limited. In this study we determined the mosquito species composition and population dynamics in areas of increased vulnerability to vector borne disease transmission, as well as investigated the resistance status of major nuisance and disease vectors to insecticides including the underlying mechanisms of resistance. High mosquito densities were recorded in Thessaloniki and Evros, with Aedes caspius, a nuisance species, Culex pipiens, a known vector of WNV, and Anopheles hyrcanus a potential vector of malaria being among the most prevalent species. Both vector species peaked in late summer. Aedes albopictus was recorded at high densities in Thessaloniki, but not Evros. Notably, Cx. pipiens hybrids, which show an opportunistic biting behavior and are suspected to be involved in the transmission of the WNV, were recorded in considerable numbers in Thessaloniki and Attica. Cx. pipiens and An. hyrcanus, but not Ae. caspius mosquitoes, showed moderate levels of resistance to deltamethrin a product used in vector control programs. The presence of resistance in areas not exposed to vector control indicates that other factors could be selecting for resistance, i.e. pesticide applications for agriculture. Both L1014F and L101C kdr mutations were detected in Cx. pipiens populations, with the majority of the mosquitoes being homozygous for the resistant mutation L1014C, which is however not well characterized. An. hyrcanus resistance could not be associated with mutations at the L1014 site. The Ace-1 mutations conferring insensitivity to organophosphates and carbamates were detected at low frequencies in all Cx. pipiens populations, indicating a low selection pressure. Increased activity of P450s and esterases was found in Cx. pipiens individuals from Thessaloniki. Our study contributes evidence for the application of sustainable and efficient vector control strategies and the prevention of disease outbreaks.