Bed bugs, mosquitoes, cockroaches. Are any insects more reviled? Earlier this year the "Ask Marilyn" column in Parade Magazine took a swipe at the first pest and backhanded the second.
Responding to the question “Would the elimination of bedbugs affect our planet?” the column’s maven, Marilyn vos Savant, ultimately responded “no” after touting the virtues of DDT. But before getting into bed bugs, she exclaimed, “Readers usually ask this question about mosquitoes!” and then opined “complete eradication of these flying disease vectors would be a boon to mankind.”
Many Alaskans would agree.
For example, in June 1847 Alexander Hunt Murray, who established Fort Yukon for the Hudson’s Bay Company, noted in a journal entry, “I must say, as I sat smoking my pipe and my face besmeared with tobacco juice to keep at bay the d—d mosquitos still hovering in clouds around me, that my first impressions of the Youcon were anything but favourable.”
It’s okay to whine about mosquitoes. Who doesn’t? But advocating complete eradication is humming a completely different tune. Marilyn vos Savant was listed in the Guinness Book of World Records as having the “Highest IQ” in the world. But she’s not being very smart about DDT.
Bed bug populations climbing
Mosquitoes have been tormenting Alaskans for tens of thousands of years. Bed bugs are the new pest on the block. One problem with cheerleading for DDT is that the insecticide is no longer an effective treatment for bed bugs.
The common bed bug infests chickens and bats in addition to humans. In fact, prehistoric humans may have first encountered bed bugs when they occupied caves with infested bats. People proved to be ideal hosts.
Bed bugs have been crawling out of dark crevices in Anchorage and other parts of Alaska in recent years. The pests are easily spread by luggage and clothing. Some apartments and hotels have experienced infestations. Anchorage schools and dorms at the University of Alaska Anchorage have also reported outbreaks.
According to Ken Perry, general manager for Pied Piper Pest Control in Anchorage, when “you walk in and there’s bed bugs all over the walls ... you know they have a very serious problem.” Several websites encourage victims to report close encounters with bed bugs in local hotels.
As creepy as these reports are to those who live here, Alaska’s bed bugs are slackers compared with their hard-working relatives in other cities, large and small. Articles from sources as disparate as the New York Times and the conservative think tank, The Heartland Institute, have ascribed some or all of the pest’s resurgence to the banning of DDT in 1972.
Conservatives have blamed the usual suspects – environmentalists, government, illegal immigrants, and liberals – for the DDT ban, and many have called for reauthorizing its use in the United States. In voicing support for DDT, Marilyn vos Savant appears to be scratching the same itch as her fellow New Yorker, Howard Stern, the self-proclaimed “King of All Media,” who can be seen exercising his right to free speech regarding bed bug control in a YouTube video (parental advisory - explicit content).
Risks of DDT outweigh the rewards
Contrary to the assertions of vos Savant and others, reinstating DDT is unlikely to stop the resurgence of bed bugs. Bed bugs were developing resistance to DDT several decades before the insecticide was banned in the United States. A few years ago DDT was found to be the least effective of 12 insecticides tested on bed bugs overrunning poultry farms. Since the 1960s bed bugs have also developed resistance to other formerly effective insecticides – malathion and pyrethroids – largely because they disrupt bed bug physiology in ways similar to DDT.
Spraying more DDT could, however, wreak havoc on ecosystems and human health. While deniers claim bald eagles and other species were unaffected by the use of DDT, people who know what they are talking about know otherwise. Rachel Carson raised serious concerns about DDT – enough to get the insecticide banned – after her book “Silent Spring” was published 50 years ago. Carson’s book spurred scientific research on the environmental impacts of DDT. Enough evidence had accumulated 30 years ago to confirm many of her concerns.
I’ll cite only three examples from hundreds of studies. In 1970, D.A. Ratcliffe published an exhaustive review of eggshells from British birds.
Eggshells collected from various parts of Britain during the past century showed a significant, widespread and unprecedented decrease in eggshell thickness and density among some species. Species that consumed other birds or fish were most susceptible. Widespread eggshell thinning was first observed in the late 1940s, a few years after the commercial release of DDT in Britain. Almost simultaneously, a couple of American scientists, J.J. Hickey and D. W. Anderson, found a similar unprecedented decrease in eggshell thickness by examining museum specimens of over 23,000 eggshells of 25 North American species. Other studies have confirmed the presence and involvement of DDE, a substance produced by the metabolism of DDT. A controlled laboratory experiment by Jeffrey Lincer, published in the Journal of Applied Ecology, showed eggshells of a small raptor, the American kestrel, were thinned by miniscule doses of DDE.
Proponents like to say that no humans have been harmed by DDT. For instance, the entomologist who ate spoonfuls of the pesticide in the early 1970s to prove it was harmless remained a staunch advocate until his death -- of a heart attack -- in 2004. It’s true that DDT doesn’t appear to be acutely toxic to humans. However, there’s growing evidence that DDT and DDE may be associated with breast cancer, diabetes, decreased semen quality, spontaneous abortion, and impaired neurodevelopment in children. Some of these maladies take decades to express themselves. Because of this, many experts – those who haven’t consumed spoonfuls of the toxin – advise using DDT for mosquito and other pest control only as a last resort.
Breaking the food chain
When she defended DDT in her Ask Marilyn column, vos Savant admitted, “I hear from people who worry about the food chain. They say that if it weren’t for mosquitoes, certain other animals — those who feed on them — may die off.” However, she rationalized, “Bedbugs were gone for decades and didn’t reappear until almost the new millennium. Did anything bad happen to the food chain in these parts of the world? No.”
I’m not nearly as smart as vos Savant claims to be, but I can think of three reasons why she’s fumigating the wrong swamp. First, bed bugs were never “gone.” They may have been decimated or eliminated in parts of North America, but they were still around, still building up their immunity to DDT and its successors.
Second, lots of bad things started happening to the environment when DDT was broadcast over forests, agricultural fields, and wetlands from the 1940s through the 1960s. Because DDT and DDE become increasingly concentrated as they move through food chains and because they are stored in fats, their effects are magnified over time in birds and mammals. DDT didn’t become the disaster some predicted because the Environmental Protection Agency listened to scientists and the public and banned the pesticide in the United States before its effects became even more obvious and irreversible.
Finally, it’s disingenuous of vos Savant to cite bed bugs as an example of how eliminating a pest doesn’t disrupt a food chain. There’s only one species of bed bug typically found inside human habitation. Bed bugs cowering in mattresses and sofas aren’t particularly susceptible to predation and, occupying a specialized niche at the top of the food chain, they aren’t as likely to be a critical link.
Mosquitoes are completely different. There are more than 3,500 species, over 3,000 of which don’t bother humans. Unlike bed bugs, adult mosquitoes and their larvae are eaten by numerous species of birds, bats, reptiles, amphibians, fish, and other invertebrates. Mosquitoes also pollinate plants. Eradicating all mosquitoes – vos Savant’s “flying disease vectors” – would almost certainly not be a boon to humankind.
Mosquitoes vs. humankind
Many proponents of DDT are legitimately concerned about the loss of human life to mosquito-borne diseases, like malaria. More than a million people die from mosquito-borne diseases every year.
A less drastic method to control mosquitoes with DDT, sanctioned by the World Health Organization, is currently practiced in Africa and Asia. Spraying indoor walls with low doses of DDT kills and repels mosquitoes and reduces incidence of mosquito-borne diseases. It appears to be a relatively safe method of reducing human suffering while avoiding, or at least postponing, severe environmental and health problems. Although some mosquito populations have developed resistance to DDT applied outdoors, indoor application of low doses is less likely to do so.
Nevertheless, some DDT proponents seem to be equally peeved by government regulations and the so-called “chemophobic indoctrination” and “eco-myths” perpetrated by environmentalists.
The anti-mosquito hype isn’t limited to news media and conservative bloggers. An article in the journal Nature, which concluded that eradicating mosquitoes would not have serious consequences for ecosystems, has been cited as gospel by some bloggers. The intern who wrote the piece, Janet Fang, claimed to have interviewed “scientists who explore aspects of mosquito biology and ecology.” She cited 13 scientists, an impressive number of experts for an article in a popular journal, although it’s hardly a quorum for the scientific community.
Even more disappointing, her selection of scientists was biased. Seven of the scientists were medical entomologists who studied mosquito-borne diseases and methods of treatment and control. Three of the scientists were entomologists who have worked on mosquito control methods. An insect ecologist Fang interviewed had studied mostly invasive species of mosquitoes. I’ve dissected Fang’s sources in detail because it’s highly misleading to imply widespread scientific support for eradicating mosquitoes when you’ve primarily cited scientists specializing in mosquito-borne diseases and pest control.
Nature is all about change … and other things
Vos Savant concluded her pro-DDT column with a platitude: “In short, nature is all about change.” Okay. Here’s another platitude: Nature is all about diversity. Pesticides tend to reduce biological diversity, which is not normally considered a change for the better.
I can agree with vos Savant that not every organism fills a critical niche and the balance of nature is not as delicate as some environmentalists think. Some species are clearly more crucial than others. For example, the world did just fine for millions of years without humans, and it would probably function better today without us than without mosquitoes. Of course, like most of my fellow humans, I have a vested interest in my species, and I’d like to keep our collective foot in the door. The best way to do that is to try to do what is best for all species, not just our own.
Despite vos Savant’s anthropocentric view, reinstating DDT and eradicating every mosquito would be a bad move for the world as we know it. Aldo Leopold, the founding father of modern wildlife management, wrote “If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.”
The Guinness Book of World Records retired the category of “Highest IQ” more than 20 years ago, after vos Savant had held the title for five years. The editors of Guinness decided intelligence was too difficult to measure, so no one person should claim to have the highest IQ.
So don’t ask Marilyn. She’s not even the smartest person in the world anymore.