Wow… DDT residues have been killing mosquitoes for 40 years

The greatest manmade chemical of all time — still working despite being banned in 1972.

ddt_weapon_of_mass_survival_against_malaria

The media release is below.

Read the study.

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Growing mosquito populations linked to urbanization and DDT’s slow decay

Rising temperatures due to climate change were found to have less influence on mosquito populations than land use changes and the decay of residual DDT in the environment

UNIVERSITY OF CALIFORNIA – SANTA CRUZ

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Mosquito populations have increased as much as ten-fold over the past five decades in New York, New Jersey, and California, according to long-term datasets from mosquito monitoring programs. The number of mosquito species in these areas increased two- to four-fold in the same period.

A new study finds the main drivers of these changes were the gradual waning of DDT concentrations in the environment and increased urbanization. The findings were published December 6 in Nature Communications.

The potential effects of climate change on the spread of insect-borne diseases is a major public health concern, but this study found little evidence that mosquito populations in these areas were responding to changes in temperature or precipitation.

“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,” said corresponding author Marm Kilpatrick, associate professor of ecology and evolutionary biology at UC Santa Cruz.

Kilpatrick explained that the effects of climate change are expected to be seen at the edges of species’ geographic ranges, as species adapted to warm climates move further north and cold-adapted species retreat from the southern parts of their ranges. So a tropical species like Aedes aegypti, which transmits Zika, dengue, and other human diseases, could expand its range northward in the United States as temperatures warm.

“On the cold edge of a species’ distribution, temperature matters a lot. In Washington D.C., for example, where Aedes aegypti is not common now, it might become more common if the winters get milder. Whereas in Florida, urbanization and mosquito control efforts are more likely to be the dominant drivers of mosquito populations,” Kilpatrick said.

Urbanization is an important factor because it changes the species composition in an area, favoring the types of mosquitoes that live near and feed on people, such as Aedes aegypti, and causing other species to decline, such as those adapted to wetlands and other natural habitats.

Mosquito control programs continue to help limit mosquito populations in many areas, but currently available techniques are not nearly as effective as DDT was, Kilpatrick said. “Everyone knew DDT was an extremely effective insecticide, but I was surprised by how long-lasting its effects were. In some areas, it took 30 to 40 years for mosquito populations to recover,” he said.

More than a billion pounds (600 million kilograms) of DDT were used in the United States from the 1940s through the early 1970s. Its use was curtailed in the 1960s and finally banned in the United States in 1972 because of adverse environmental effects, especially on birds and other wildlife, as well as potential human health risks. Yet DDT was still detectable in soil cores as recently as 2000 in New York state, where DDT use was much higher than in New Jersey and California.

In all three regions, both mosquito abundance and the number of species decreased dramatically during the period of DDT use, then steadily increased as the amount of DDT in the environment declined. In New York, the researchers found, patterns of DDT use and its concentration in the environment could explain most of the long-term trends in mosquito populations. In New Jersey and California, however, the analyses showed that urbanization was also an important factor.

Average annual temperatures showed surprisingly little correlation with mosquito population trends. “Precipitation was more important than temperature, but land use was more important than either of those factors,” Kilpatrick said. “The long-term impacts of land use changes on ecosystems are sometimes underappreciated.”

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The coauthors of the paper include Ilia Rochlin and Dominick Ninivaggi at Suffolk County Vector Control in New York; Ary Faraji at the Salt Lake City Mosquito Abatement District; and Christopher Baker at UC Davis.

8 thoughts on “Wow… DDT residues have been killing mosquitoes for 40 years”

  1. The UN banned DDT? I’m not sure about that. I know there was an effot by the UN to do so, but my understanding was that effort didn’t succeed. However, my understanding is there’s only one company in India that manufactures DDT currently, and they closed one of their three plants. This may become a defacto ban based on a lack of production.

  2. Brian,
    the rest of the world including sub Saharan Africa stopped using DDT entirely. The UN banned it. UN handouts were often predicated on a third world country stopping use of DDT.

    It is only just recently that a _few_ African nations started using DDT again. The deaths of children in Africa shot up from Malaria and associated diseases. It is slowly but surely coming down again as the use of nets and spraying of houses/huts with DDT progresses.

  3. Quite a few years ago, my wife and I were living in Mexico when we both were infested by crab lice (yes, I know all the jokes) we found some DDT soap at the local Pharmacy which they told us was for dogs. We used it in the shower for a couple of days and no more lice, no ill effects. Now living in Malaysia, I wish DDT was available now just to keep the mozzies and other pests at bay, none of the expensive, professional chemicals now available seem to be as effective.

  4. A few years ago Gore was warning of suburban sprawl being a real danger to resources and land use. Now urbanization is a danger in that it may increase the mosquito population. HA!

    Malaria is not strictly a tropical disease. In the 1920 the NYT wrote of millions in Russia, not exactly a tropical paradise, infected with malaria.

    A solution exists as this article demonstrates, DDT.

  5. Bernard,

    Your postulation that 70 million malaria deaths could have been prevented by the continued use of DDT is a misinterpretation of reality. In fact, according to CDC malaria was eliminated from the US in 1950, where few of these malarial deaths and novel infections occur. The banning of DDT in the US has limited impact on its continued use in malarial hotzones. Furthermore, the aforementioned hotzones, many reside in sub-saharan Africa, have continued use of DDT despite the US ban. This implies that simply using DDT may not be sufficient to prevent malaria. Perhaps, more community driven efforts are needed as crucial supplements to DDT use such as; bed nets, window screens and proper education. This is a rebuking of simply taking a “panacea pill”.

  6. Logic of the PC crowd: If it works, is very beneficial , harmless and affordable, BAN IT!!!
    If it doesn’t work, is harmful, dangerous and very costly, make it mandatory and subsidize it.

  7. Excerpt from ‘What is the Primary Fundamental Right?’

    “Prior to 1937 hemp was one of the most versatile crops in America. Not only could it be used as a clothing material but its production tons per acre for paper pulp was better than that for trees. There are many reasons given why it had a prohibitive tax placed on it which stopped its profitable production including competition from oil based plastics producers to stopping black men giving it to white girls and then having sex with them. What ever it was the effect was to promote cotton production.

    Cotton, unlike hemp, requires massive amounts of pesticides and herbicides in its production. In the late forties and fifties cotton farmers found the benefits of cheap DDT which they then used excessively. Mainly because of this over use DDT went on trial. In 1972 the EPA Administrative Law Judge Edmund Sweeney after a lengthy hearing stated that “DDT is not a carcinogenic hazard to man. … The uses of DDT under the regulations involved here do not have a deleterious effect on freshwater fish, estuarine organisms, wild birds, or other wildlife. … The evidence in this proceeding supports the conclusion that there is a present need for the essential uses of DDT.”

    In what looks like a purely political strike the then EPA Chairman, William Ruckelshaus, a protoenvironmentalist, went against his own judges findings and banned DDT with very little evidence showing there was any danger to anything or anybody. Since then over 70 million people have died from malaria, mainly children and young mothers. Their deaths could possibly be attributed to a now discredited book ‘Silent Spring’ written by super hypermaternal Rachel Carson.

    If hemp hadn’t been ‘banned’ and if cotton production hadn’t increased consequently and if Ruckelshaus hadn’t done what he did, then the West Nile Virus probably would not be a problem today in 46 American, 6 Canadian and 5 Mexican states. Government by hysterics.”
    http://www.primaryfundamentalright.org/index.php?pageName=pfrWhatIs

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