Drive聽through the countryside in summer and you will inevitably end up with a windscreen plastered with dead bugs. The messy聽ritual has now聽inspired聽an innovative new study designed to look at what effect traffic has on the abundance of local insects.
Amanda Martin, at Canada鈥檚 Environment and Climate Change Canada (ECCC) department, says that the inspiration for the study came from the apparent downward trend in global insect numbers.
鈥淭here are a number of possible explanations for insect declines over time, like increased use of insecticides or declining availability of wetlands and ponds for breeding,鈥� says Martin. But the potential effect of car vs. insect collisions on increasingly聽busy roads hadn鈥檛 been well-studied.
Advertisement
Bring out the flypaper
To test this relationship, Martin and her colleagues needed to compare flying insect presence between roads with differing traffic levels. But how do you accurately sample thousands of flying insects along a roadway?
鈥淲e thought, wouldn鈥檛 it be great if we could collect insects as they were hitting the car?鈥�, she says.
So聽the team turned聽its research vehicle into a giant, mobile piece of flypaper, outfitting it with large sticky trap panels on the grill and roof. The vehicle was driven on ten segments each of high and low traffic roads in southwestern Ontario. The team then counted and categorised the insects stuck to the traps.
They found that there were 23.5 per cent fewer insects on high-traffic roads than on low-traffic roads.
Martin notes that this doesn鈥檛 necessarily show that more insects are being splattered on busy roads. For example, it鈥檚 possible that greater car emissions on high-traffic roads are killing nearby insects, or that busy roads encourage ride-hitching, non-native plants to spread and beat out roadside vegetation more suitable as habitat and food for insects.
Whatever the direct cause, the drop in abundance is concerning. Insects play a pivotal role in terrestrial food webs, and provide services for humans by pollinating crops, says Martin.
