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Mosquito population growth in US driven by decay of DDT, urbanization
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New research suggests a growth in mosquito populations in the United States has been driven by the decay of residual DDT in the environment and urbanization, not climate change.
A. Marm Kilpatrick, PhD, assistant professor in the department of ecology and evolutionary biology at the University of California, Santa Cruz, and colleagues found mosquito populations had increased by as much as 10-fold in some areas amid concerns over the emergence of mosquito-borne diseases such as Zika, dengue and chikungunya viruses.
Aedes aegpyti — the primary vector for Zika virus.
Source: James Gathany/CDC
“At first glance, recent increases in mosquito populations appear to be linked to rising temperatures from climate change, but careful analyses of data over the past century show that it’s actually recovery from the effects of DDT,” Kilpatrick said in a news release.
The practice of spraying DDT to control mosquito populations was banned in 1972 due to concerns about its impact on the environment and animals, but not before more than a billion pounds of the insecticide were used, according to the release.
“Everyone knew DDT was an extremely effective insecticide, but I was surprised by how long-lasting its effects were,” Kilpatrick said. “In some areas, it took 30 to 40 years for mosquito populations to recover.”
Kilpatrick and colleagues analyzed previously unpublished datasets dating back eight decades from New York, New Jersey and California, and found that changes in mosquito communities were “strongly correlated with changes in DDT concentration increases and urbanization.”
Mosquito populations and species declined in all three regions during the time DDT was used. In New York, where DDT was still detectable in soil cores in 2000, use of the insecticide explained most of the long-term trends in mosquito populations, according to the release. In New Jersey and California, urbanization was shown to also be an important factor.
Average annual temperatures showed little correlation with mosquito population trends, the release noted, and Kilpatrick said precipitation was a more important factor.
“These results illustrate the far-reaching impacts of multiple anthropogenic disturbances on animal communities and suggest that interactions between land use and chemical use may have unforeseen consequences on ecosystems,” Kilpatrick and colleagues concluded. – by Gerard Gallagher
Disclosures: The researchers report no relevant financial disclosures.
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