Entomologists call for eternal vigilance against a resurgent foe
SAN DIEGO – Amid the high-tech science showcased at the Entomological Society of America’s annual meeting, bedbug specialists repeatedly called for a low-tech defense: More people need to learn what a bedbug looks like.
Today’s bedbug strains often carry considerable resistance to the widespread pyrethrin-based pesticides licensed for indoor use, said Dini Miller of Virginia Tech in Blacksburg. Heat treatments, sniffer dogs or repeated courses of spraying get costly and don’t prevent repeat infestations. Do-it-yourself options, often based on vague, wishful or outright wacky notions of bedbug biology, have their perils too. “Technology alone is not going to save us,” Miller said.
What will? “Eternal vigilance,” according to a December 14 presentation by Michael Potter of the University of Kentucky in Lexington.
Headlines about the resurgence of bedbugs in the industrialized world have alarmed people about the fiercely itching bites and creepy stealth of the crevice-loving bugs. But as far as practical matters like recognizing a bedbug, “people are clueless,” Potter lamented.
So go Google photographs of the bugs and learn the signs of infestation. Pictures typically show the adults, reddish-brown and roughly as long as a pencil eraser is thick. The earlier stages are smaller and often paler.
Black smudges from bug excrement along mattress or couch seams may be easier to spot than the bugs themselves. And in spite of the name, bedbugs thrive in crevices that aren’t the least bedlike, such as the crannies of electronics. Again and again in the symposium, researchers warned against impulsive adoption of computer monitors (or comfy chairs or anything else) set out on a curb for free.
Speakers told of infested ambulances, theaters, fancy New York stores, libraries, subways, planes and even corpses. (The bedbugs didn’t appear to be feeding on the corpses but were ready to taste their living attendants.)
Yet even as entomologists lament the public’s inability to recognize the pests, researchers themselves may have missed something in the bedbug-identification department. Specialists may not have recognized another species among all the Cimex lectularius bedbugs in the United States, suggested Gale Ridge of the Connecticut Agricultural Experiment Station in New Haven.
Having revised her talk during the previous week to include the idea, she brandished a plastic disk holding a bedbug. A colleague had sent it to her as a token, but when she admired it under a microscope, the bug looked hairier and somewhat different in shape around the front. A small percentage of other bedbugs that have crossed her desk recently have resembled it, and another bedbug taxonomist is consulting with her over possibly naming a new species.
Many researchers are waiting to go back and look at their bugs and to hear the results of DNA analyses before embracing the idea, Miller said. “If it’s true, she said, “it’s amazing.”
Ridge originally signed up to talk about trying a bug-killing fungus, Metarhizium anisopliae, as a possible control for bedbugs. She zipped through a report on her first round of tests: In the lab, bugs died, but probably not fast enough to satisfy a besieged homeowner.
To combat pesticide resistance, other researchers are harnessing a technique called RNAi, administering snippets of genetic material that gum up an organism’s insides at the molecular level. Fang Zhu of the University of Kentucky presented results from experiments that treated resistant strains of bedbugs with RNA to disrupt the enzyme known as cytochrome P450 reductase. The treated bedbugs became more susceptible to the pesticide deltamethrin, so Zhu and her colleagues propose that a detoxification process involving the cytochrome P450 enzyme is one way that bedbugs resist insectides.
RNAi itself might someday become part of a treatment, says Kenneth Haynes, also of the University of Kentucky. In his own talk on resistance, he decried a persistent hope for bedbug control.”There is no doubt in my mind that DDT would not be a solution for us in the modern day,” he said.
DDT resistance in bedbugs, recorded in 1948, was among the first warning signs of insect powers to evolve ways to dodge DDT. Some modern lab work shows they can still do it.
G.L. Ridge and A. Bharadwaj. Cimex lectularius L. (Heteroptera: Cimicidae) control using the entomoppathic fungus Metarhizium anisopliae. Presented December 12, 2010 at the annual meeting of the Entomological Society of America, San Diego, Calif.
MUVE Section Symposium: Bed Bugs, People, and Politics. Eight speakers presenting December 14, 2010 at the annual meeting of the Entomological Society of America, San Diego, Calif.
F. Zhu et al. Molecular analysis of NADPH-cytochrome P450 reductase in the bed bug, Cimex lectularius (Hemiptera: Cimicidae). Presented December 12, 2010 in San Diego at the annual meeting of the Entomological Society of America.
VL Saenz. Population genetic structure within and among aggregations of bed bugs (Cimex lectularius). Presented December 12, 2010 at the annual meeting of the Entomological Society of America, San Diego, Calif.