What Warming Means for 4 of Summer’s Worst Pests

Summer may mean it’s time for outdoor fun in the sun, but it’s also prime time for a number of pests.  All that extra time outdoors can bring everything from poison ivy rashes to exposure to Lyme disease from tick bites.  And of course there’s that ubiquitous summer menace, the mosquito.

With the rising temperatures brought about by global warming, the risks posed by these pernicious pests could also be increasing.  A warmer climate can mean expanded habitats for many pest species, as well as increases in their numbers.  Here’s what research suggests will happen with four key summertime pests as the world warms:

• Mosquitoes
  While some are merely an itchy nuisance, others come with the risk of spreading diseases like malaria, West Nile virus and dengue fever, including the invasive Asian Tiger mosquito, which first appeared in the U.S. in 1985.
  
  As temperatures around the country rise, the areas that are conducive to such mosquitoes could expand, and the insects could start to emerge earlier in the year, meaning more opportunities for bites that could spread disease.
• Poison IvyThe impacts of climate change on poison ivy have more to do with the cause behind rising temperatures than the warming itself.  Plants need carbon dioxide — the key heat-trapping greenhouse gas — to fuel photosynthesis. Experiments that exposed poison ivy plants to different levels of CO2 have found that “poison ivy grows faster when there’s more CO2” and it produces more leaves that carry the plant’s toxic oil, Doug Inkley, a NWF scientist, said.
  
  Those oils, which put the “poison” in poison ivy, can vary in their chemical structure, and high CO2 levels also cause the plants to produce a more toxic form, “so climate change is not doing us any favors there,” Inkley said.
• Deer Ticks
  As temperatures rise, there is concern that ticks could spread into newly suitable habitat and bring Lyme disease and other pathogens with them.  They have already expanded northward into Canada, where the number of reported cases of Lyme disease doubled between 2009 and 2012, according to Canadian government figures
• Red Fire Ants
  With warming, those low temperatures don’t get as cold, meaning colonies could be less inhibited.  Lloyd Morrison, a National Park Service ecologist who has studied them, did a study in 2005 that modeled the potential expansion of the imported red fire ant with climate change and found that warming temperatures would expand suitable habitats by about 5 percent by mid-century and then by 21 percent towards the end of the century.  This would mean imported red fire ants could be found as far north as Nebraska, Kentucky and Maryland.
  
  And while these ants can certainly provide an unpleasant encounter for any unwitting humans who come across them — their en masse bites inject their victims with venom that produces a burning sensation and raises blisters that can become infected — they are actually more of a threat to local wildlife.  Swarms of ants can easily overwhelm young birds in ground nests and small animals like mice, Inkley said.

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