A comparative assessment of mosquito trapping methods for vector surveillance in Scotland

While mosquito vector-borne disease (VBD) risk remains low in Northern Europe, surveillance is needed to monitor potential vector species. However, most mosquito trapping methods have been evaluated only in areas of high mosquito density, with limited knowledge of their sensitivity in low-abundance areas. Here, we assessed the relative performance of four commercially available traps in an urban setting in Scotland, where mosquito density is low.

Two trap evaluation experiments were conducted in an urban marsh in Glasgow City during August 2023. In experiment 1, the Biogents BG-Pro (BGP), Biogents BG-Sentinel (BGS), and CDC miniature light traps (LT) were compared over 15 days using a 3 × 3 Latin square design. A subsequent experiment incorporated the Mosquito Magnet (MM) trap to compare it with the other three traps over 12 days using a 4 × 4 Latin square design. Alongside these experiments, two CDC gravid traps (GT) were trialled across 24 days to target blood-fed and gravid mosquitoes. Mosquitoes were morphologically identified to species and species-group level, and polymerase chain reaction (PCR) assays were used to identify Culex pipiens s.l. biotypes.

Over the 96 trapping events, 150 mosquitoes were collected from eight species. Mosquito abundance was generally low (mean abundance: 1.61 per day ± 1.89). The most abundant species collected was Anopheles claviger (n = 63), followed by Culiseta morsitans (n = 28). In Experiment 1, there was no significant difference in mean mosquito abundance among the BGS, BGP, and the LT. In Experiment 2, there was a significant positive association between the MM and daily mosquito abundance. The MM also collected more species than the other trap types (6 compared to 1-4 species). Gravid traps collected 19 mosquitoes representing three species, of which 21% were gravid or blood-fed.

While the MM caught more mosquitoes than other methods, this was likely due to its more consistent and higher-volume CO₂ output. However, important potential vector groups (Culex) were present only in the BGS, BGP, and LT. No single method consistently captured all species, indicating that a combination of methods may be necessary for comprehensive vector surveillance in Scotland.