Surveillance and control of invasive aedes species in the eastern black sea area of Turkey

Abstract

Objective: Invasive mosquito species are a huge problem world-wide and can cause serious mosquito borne disease epidemics. Recent surveys in Europe revealed that many autocthonous cases of chikungunya are related to the invasive Aedes albopictus and Aedes aegypti species. Extensive surveillance of these species and other invasive Aedine mosquito species is required for the prevention and timely response to possible outbreaks. This study focuses on surveillance and control operation success in the Eastern Black Sea region of Turkey. Methods: This surveillance study was performed during the 2016-2017 vector active season. Three cities were surveyed according to ECDC and CDC guidelines. Control operations were performed during the second half of the 2017 active season under the supervision of the Turkish Ministry of Health's Zoonotic and Vector-borne Diseases Department. IGR, a Bti/Bs mix and liquid Bti were used for larval control. Different pyrethroids, nicotine mimics and natural products were used for adult control. Six areas of Ae. albopictus and four areas of Ae. aegypti were selected for assessment of population fluctuations and control operations success. Results: Twenty-two widely established and two locally established Ae. albopictus populations were detected in 2016. Four widely established and ten locally established Ae. aegypti populations were detected in that the same year. In 2017, 544 potential larval breeding sites were tested in three cities. Persistent infestations of Ae. albopictus were discovered in 194 of these locations. Ae. aegypti was detected in only 25 locations throughout the area. Population densities fluctuated during the season with two population peaks (June-minor, September-major) of Ae. albopictus in 2016. In contrast, population peaks were seen in August and October in Ae. aegypti. The average larval control success was 69%, but adult control success was only 46% for all areas throughout the season for Ae. albopictus. Similar results were observed for Ae. aegypti, with larval control success at 61% and adult control success at 37% after control operations were performed. Conclusion: The study revealed the persistent rapid expansion and high population density of two invasive mosquito species in the infested areas. Control success was achieved at over 60% for larvae and around 40% for adults despite the limited time of this study. The low level of control operation success may be explained by many factors, but the principal factors are the geographical features of the region, climatic variations and restrictions on insecticide usage in tea plantation areas. Therefore, an urgent strategic plan is essential for integrated control strategies.