It’s July and mosquito field season is in full swing. As an introductory post, I thought it would be fun to show you all my daily field work routine.
My day started off around 8:00 am collecting mosquito traps. The afternoon before, I had set up these traps at a mix of suburban and wild sites around Wake County. The traps involve a battery powered fan that pushes mosquitoes down into a canister and are baited with solid carbon dioxide, or dry ice. Mosquitoes are attracted to carbon dioxide, as humans and other host animals emit this chemical as a waste product.
Once back in the lab, I began sorting through all of the traps. Although our target organism is the mosquito, we do occasionally catch other blood-feeding insects, like tabanids (horse flies).
All of the caught mosquitoes are identified to species. This step is important in characterizing what types of mosquitoes are common in different habitats. The mosquito below is Aedes albopictus (although a little beat up and missing some legs), the Asian tiger mosquito, an invasive species that is now very common in this area.
After identification, each mosquito is dissected so that we can look for heartworm larvae. In the dissection below, the bright white rope-like structures are the malpighian tubules, which house the developing L2 heartworm stage. The two protruding structures are the ovaries.
The ovaries are mounted onto a slide for us to determine if the female is parous, or if she has laid eggs before. This gives us a general idea of how old a mosquito is (relatively young if she hasn’t; older if she has).
We sorted, identified, and dissected mosquitoes until 6:30 pm, ending a successful day of field work. Next time I post, I’ll chat more about parity determination.
In the spirit of July 4th, I’ll leave you with this unintentionally patriotic snapshot from a blood-feeding trial today. We have found a simple way to dye blood so that feeding preference can easily be assessed by the difference in colors. Squished mosquitoes yield red and blue blood! But more on that another time…
