PCOC - Fall 2015 - (Page 12)

German Cockroach Control: Are Baits the Silver Bullet? By Jules Silverman, Ph.D., North Carolina State University The German cockroach, Blattella germanica, is a widespread pest found throughout the world. Interestingly, unlike just about every other insect pest, it is almost never found apart from human-built dwellings. This cockroach depends on us for its sustenance: it eats what we eat. Though there is evidence that cockroaches can spread human pathogens, it is most notably a health hazard due to the production of allergens that trigger asthma, which have particularly serious affects on inner-city youth. These allergens can build up rapidly due to the high reproductive capacity of cockroaches, therefore it is imperative to eliminate these pests when detected. Liquid residual spray insecticides were used almost exclusively by pest management professionals to control German cockroaches until the mid-1980s. These were primarily organophosphate, carbamate or pyrethroid formulations that had varied impacts on their cockroach target. Some were repellent, avoided by the insects, while cockroach populations developed resistance to others. Then baits, beginning with the active ingredient (AI) hydramethylnon, were introduced to the professional and consumer markets. The toxicant was mixed with food ingredients. Insects would detect, then consume the food, while unwittingly ingesting a lethal dose of insecticide. Other insecticides incorporated within baits that are both very active and that go largely undetected by the cockroach include fipronil, indoxacarb, abamectin, dinotefuran and clothianidin. Baits have another advantage over liquid residual sprays: they kill cockroaches both directly and indirectly (secondary-kill, Domino Effect™). Here, cockroaches directly consuming bait return to hiding areas, excreting insecticide-laden feces, before dying. Other cockroaches will consume these excretions and they, in turn, die. This is an effective way of delivering insecticide to locations harboring large cockroach numbers. The hydramethylnon-based baits were initially very effective, reducing cockroach populations by more than 90 percent. This excellent performance continued throughout nearly all accounts in the United States. However, in some locations, bait efficacy declines became evident: despite persistent bait applications, cockroach populations were increasing rather than declining. After an exhaustive search by the manufacturer to determine the cause of this product performance decline (AI resistance?, AI and inert ingredient repellency? other), we determined that surviving insects from these accounts avoided eating the sugar glucose - the primary feeding stimulant in the bait. Glucose aversion is a heritable trait, and thus, we were skewing the populations toward glucose-averse individuals by applying bait with glucose as the feeding stimulant. We later determined that glucose-averse cockroaches perceive glucose as a deterrent, much like caffeine. Substituting fructose for glucose in the baits improved product performance considerably. There is recent evidence that certain populations of German cockroaches have become resistant to the active ingredients in some bait products. We have identified field-collected cockroach strains with individuals that are both insecticide resistant and glucose-averse. In addition, secondary kill is compromised in these resistant strains. www.pcoc.org / Fall 2015 12 http://pcoc.org/

Table of Contents for the Digital Edition of PCOC - Fall 2015

President’s Message
Martyn’s Corner
PCOC 2015 Pictorial Highlights
German Cockroach Control: Are Baits the Silver Bullet?
Is Bed Bug Heat Treatment Hot Enough for Multi-Unit Housing?
Federal Update
Insurance : Get the Facts Before They Get You: Accident Investigations & Employee Safety
State Capitol Report Do You Feel the Sunshine?
Firm Profile North American Home Services
Index to Advertisers

PCOC - Fall 2015