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Guest Scientist Blog: Mosquito Larvae Hide and Seek in a Chapparal Ecosystem

SEES Mosquito Mapper intern Lindsay W. in the field, sampling a mosquito larvae habitat site in her study area. Photo credit: Author.

California has recently emerged from a multi-year drought, but I live at the edge of a town in the chaparral where water is typically scarce. I often travel miles by car to find potential mosquito habitats, only to find no larvae in those water sources.

I eventually contacted Vector Control in hopes that they could direct me to potential breeding sites, and they sent me a few locations. As of yet, most sites I’ve visited have had water and no mosquitoes. However, one site, Aubrey Pond in Old Poway, had neither mosquitoes nor water. Possibly this condition is the result of the drought, when many ornamental ponds and fountains were drained.

In addition to conserving water, San Diego County is also vigilant about applying larvicide to standing bodies of water. Larvicide is regularly sprayed roughly every three weeks, further lowering the county’s mosquito populations and the number of mosquito bites.

Ironically, the one place I have found mosquito larvae in is a creek in my neighborhood. The creek’s residents include coyotes, rattlesnakes, and poison oak, but also large panfish, ducks, bee colonies, mourning doves, and hummingbirds. To get to the mosquito habitat, I hike down a one-mile trail along this creek to an area with rock pools and dense tree cover. At this point I need to leave the trail, so a hiking stick comes in handy in case I find a rattlesnake hiding under the rocks. Because the water was out of my reach, I needed acreative solution, and taped a paper cup to the end of the hiking stick to scoop up water with mosquito larvae.

After collecting water here, I go to check my traps, which are attracting ants instead of mosquitoes. A possible reason for this is that the mosquitoes I have identified nearby, such as those in the Culex or Culiseta genera, prefer cooler temperatures better sustained by rocks and soil than the plastic bottle traps that are more exposed to air temperatures. I am learning that the ecology relating to mosquitoes is complex—poorer water quality does not necessitate the presence of mosquitoes, and, while many biting mosquitoes are most active in hotter temperatures, there are other mosquitoes that thrive just as well if not better when it is a little bit cooler. Completing field studies such as this will help us to better understand what makes mosquitoes thrive and what keeps their populations in check.

Last week I collected many larvae at the creek, but they died almost immediately after. The next day my neighborhood got sprayed, and now there are no mosquito larvae. I will be checking back on this site to determine how long larvicide can keep the creek habitat mosquito-free.

Lindsay W. is a high school student from California who is working on a research project this summer using the GLOBE Observer Mosquito Habitat Mapper. Her virtual internship is part of a collaboration between GLOBE Mission Mosquito and the NASA  Texas Space Grant Consortium (TSGC) to extend the TSGC Summer Enhancement in Earth Science (SEES) internship for U.S. high school (http://www.tsgc.utexas.edu/sees-internship/). She shares her experience so far this summer in this guest blog post.

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