Vertical Distribution of Culicoides Biting Midges in Temperate Forests

Abstract

Culicoides biting midges are small dipterous insects known as biological vectors of arboviruses, protozoa, and filaria parasites worldwide. Many studies on Culicoides focus on trapping them at ground level, without considering the best trap heights for different vector species. This implies that we might overlook insects positioned higher in the canopy. From June to August, we used UV traps to catch Culicoides biting midges at three different heights in three temperate mature forest areas in east Lithuania, Baltic region of Europe. We conducted this study to test the differences in midge numbers, male and female proportions, and female parity at each height. We caught the majority of biting midges (80.6%) at the mid-canopy and high-canopy. A higher number of female Culicoides midges than males was caught, with the proportion of males varying based on height and reaching its lowest point at ground level. No significant difference between the proportion of nulliparous and parous females caught at different height was detected. Culicoides pictipennis and C. festivipennis were the most common species of biting midge we found. They were found in the mid-canopy (86.8%) and the high-canopy (50.0%), respectively. Culicoides kibunensis was next, found at ground level (66.2%), and C. punctatus was found at the high canopy strata (63.0%). Each species’ abundance was seasonal dependent. Information on the vertical distribution of vector species in the temperate forest ecosystem is an important step in understanding patterns of vector borne disease transmission in wildlife.