Insect Attack

mediterranean fruit fly, or the medfly. Photo by Scott Bauer/ USDA Agricultural Research Service

Friday, October 26th, 2007--

As the Department of Homeland Security surveys our borders and monitors our shampoo bottles, some entomologists are wondering whether there is another overlooked avenue for a terrorist attack--bugs. As disease-vectors and crop destroyers, experts say that bugs could be harnessed as weapons of mass destruction. "It's not been given its proportional level of attention. I don't know that we want to overreact, but I think we've dangerously under-reacted," says Jeffrey Lockwood, an entomologist at the University of Wyoming.

Insect warfare is not new. It dates back thousands of years, according to Lockwood, who is the author of a forthcoming book on insects and war. "During the times of the Greeks and Romans, war ships were often equipped with fragile earthen beehives that were plugged with grass. They would launch them onto the enemy ship. Boy it was a great way to clear the decks," Lockwood says.

More recently--during World War II-- the Japanese military had a insect vector disease program that churned out millions of diseased fleas and flies, according to Lockwood. "They had this gigantic plague and flea production facility. They could produce 50 million plague-infected fleas a month."

Today some entomologists are concerned that insects could be a cheap biological weapon for terrorists. Lockwood says that for the cost of a plane ticket and some basic insect catching- and growing-equipment, a terrorist could import mosquito eggs carrying the viral disease Rift Valley Fever (RVF) from Africa, for example. RVF affects both humans and animals. And according to the Centers for Disease Control and Prevention (CDC), there is no established course of treatment for the disease.

Establishing a RVF outbreak in this country would require: catching mosquitos, letting them feed on an animal that has the disease (there is an outbreak in Africa every few years, Lockwood says), re-collecting the mosquitos, putting them in a cage and waiting for them to lay eggs, and then taking the eggs to the U.S. and dropping them in water. "You could put thousands and thousands [of eggs] in a match box," Lockwood says. "So that would be very easy to do."

In theory, establishing a new disease, like RVF, would require only one insect. "In the case of Rift Valley Fever, if a single infected mosquito bites a susceptible sheep, or goat, cow or human--they can create the disease in that individual. These animals could then circulate the virus in their blood stream and all the other mosquitos that fed on that animal could become infected and perpetuate the disease quite rapidly," says Charles Bailey, a medical entomologist and head of the National Center for Biodefense and Infectious Diseases at George Mason University.

Our track record with invasive species that have come here (presumably) accidentally makes it clear that new insects, disease-carrying or otherwise, can successfully colonize this country without the help of evil-doers. Marjorie Hoy, an entomologist at University of Florida, Gainesville, says that an average of twelve new species of insects come to Florida and establish a population in that state every year.

Hoy attributes the naturally-occuring bug surge to leaky borders. "Only a small fraction of the U.S. mail, or shipments of freight or fruits or flowers that come into our ports, our airports, seaports are ever inspected. Those people who are sneaking in plant material, fruits, vegetables meats--are potentially accidental bioterrorists," she says. In the case of intentional insect warfare, border control for this kind of weapon would be nearly impossible, says Bailey, who served in the U.S. Army for 25 years. "If somebody is intent on introducing some of these exotic species, I don't know how you'd stop it, I really don't."

Once an insect is introduced eradication options for insects are not extensive. "It's not going to be possible for airplanes to be flying over the whole eastern seabord and spraying pesticides out to eradicate insects. It isn't going to happen," says Hoy.

In dealing with invasive pests in the past, there has been some success with other methods of control. For example, the Mediterranean fruit fly has been expunged (although it has come back a few times) with the release of sterile male fruit flies. This is paired with regularized checks for the species, Hoy says. "In medical veterinary entomology, we do had some successes. But we've had an awful lot of failures too," says Strickman. The Asian Tiger mosquito has established and spread in this country--something Strickman counts as a "horrible failure."

Given that a bug-based weapon would be hard to prevent, and hard to deal with once it happened, some bug experts are calling for better preparation. "It's a difficult problem--that's the reason we need vaccines and we need therapies in the case of an outbreak. We have to have ways in which we be prepared to treat the population," says Bailey, adding that even vaccinating would be hard given that we wouldn't know where to vaccinate or what to vaccinate for.

Lockwood and others point to West Nile virus as evidence that the U.S. is not well-prepared for bug biowarfare. Strickman says: " West Nile really got me thinking. I'll tell you before 1999 I would have said it was impossible for that to happen. But not only did it happen, it happened quickly and violently."

--Flora Lichtman

Sources

Daniel Strickman
National Program Leader for Veterinary, Medical, and Urban Entomology Agricultural Research Service U.S. Department of Agriculture

Jeffrey Lockwood
Entomologist Professor of Natural Sciences and Humanities University of Wyoming

Charles Bailey
Distinguished Professor of Biology Executive Director National Center for Biodefense and Infectious Diseases George Mason University Manassas, VA

Marjorie Hoy
Eminent Scholar and Davies, Fischer and Eckes Professor of Biological Contro Department of Entomology and Nematology University of Florida, Gainesville