Cockroaches are serious threats to human health. They carry dozens of types of bacteria, such as E. coli and salmonella, that can sicken people. Additionally, the saliva, feces and body parts they leave behind may not only trigger allergies and asthma but could cause the condition in some children.
A Purdue University study led by Michael Scharf, professor and O.W. Rollins/Orkin Chair in the Department of Entomology, now finds evidence that German cockroaches (Blattella germanica L.) are becoming more difficult to eliminate as they develop cross-resistance to the pest management industry’s insecticides. The problem is especially prevalent in urban areas and in low-income or federally subsidized housing where resources to effectively combat the pests aren’t as available.
“This is a previously unrealized challenge in cockroaches,” said Scharf, whose findings were published in the journal Scientific Reports. “Cockroaches developing resistance to multiple classes of insecticides at once will make controlling these pests almost impossible with chemicals alone.”
Each class of insecticide works in a different way to kill cockroaches. Most PMPs will use insecticides that are a mixture of multiple classes or change classes from treatment to treatment. The hope is that even if a small percentage of cockroaches are resistant to one class, insecticides from other classes will eliminate them.
Scharf and his study co-authors set out to test those methods at multi-unit buildings in Indiana and Illinois over six months.
In one treatment, three insecticides from different classes were rotated into use each month for three months and then repeated. In the second, they used a mixture of two insecticides from different classes for six months. In the third, they chose an insecticide to which cockroaches had low-level starting resistance and used it the entire time.
In each location, cockroaches were captured before the study and lab-tested to determine the most effective insecticides for each treatment, setting up the scientists for the best possible outcomes.
“If you have the ability to test the roaches first and pick an insecticide that has low resistance, that ups the odds,” Scharf said. “But even then, we had trouble controlling populations.”
Rotating three insecticides, the researchers were able to keep cockroach populations flat over a six-month period, but they could not reduce them. The two-insecticide mixture did not work, and cockroach populations flourished.
In one of the single-insecticide experiments, Scharf and colleagues found that there was little starting resistance to the chosen insecticide, and they were able to all but eliminate the cockroach population. In the other, there was about 10 percent starting resistance. In that experiment, populations grew.
In later lab tests of the remaining cockroaches, Scharf and the team found that cross-resistance likely played a significant role. A certain percentage of cockroaches would be resistant to a particular class of pesticide. Those that survived a treatment — and their offspring — essentially gained immunity to that insecticide and resistence to other classes of insecticide; even if they hadn’t been exposed to the insecticides and did not have previous resistence.
“We would see resistance increase four- or six-fold in just one generation,” Scharf said. “We didn’t have a clue that something like that could happen this fast.”
Female cockroaches have a three-month reproductive cycle during which they can have up to 50 offspring. If even a small percentage of cockroaches is resistant to an insecticide, and those cockroaches gain cross-resistance, a population knocked down by a single treatment could explode again within months.
That’s why an integrated pest management approach is critical, Scharf said. He recommends combining chemical treatments with traps, improved sanitation and vacuums that can remove cockroaches.
“Some of these methods are more expensive than using only insecticides, but if those insecticides aren’t going to control or eliminate a population, you’re just throwing money away,” Scharf said. “Combining several methods will be the most effective way to eliminate cockroaches.”
The U.S. Department of Housing and Urban Development the O.W. Rollins/Orkin endowment in the Purdue Department of Entomology supported this research.
Source: Brian Wallheimer, Purdue University
WEST LAFAYETTE, Ind. - Low-moisture products, such as flour, dried fruit and nuts, are often perceived as safe from food pathogens in consumer’s eyes despite recent bacteria outbreaks. Like other raw food commodities, these low-moisture food products are at risk for foodborne bacteria if there isn’t a “kill step” or heating process to eradicate bacteria during harvest or processing.
ROSEMONT, Ill. — BNP Media announced today that the 2020 Food Safety Summit will be a virtual experience instead of an in-person event. The Summit team is working closely with the Educational Advisory Board to offer an in-depth conference program offering real world business solutions for today and planning for tomorrow. The virtual Summit will feature the world's leading authorities examining the most up-to-date innovations in the food industry. The education program, access to participating exhibitors, and networking opportunities will be live online from Monday, October 19 - Thursday, October 22. To register to attend visit www.foodsafetysummit.com.
"Given the continued uncertainty around travel and the importance of health and safety for the entire food safety community, the difficult decision has been made to transition the upcoming in-person Food Safety Summit event in Rosemont, IL to a fully virtual event October 19 - 22, 2020," said Scott Wolters, Chief Events Officer, BNP Media, producers of the Summit. "We have refocused our efforts on our newly launched virtual platform, providing an opportunity for food safety professionals to have access to world class education, expert insights, valuable content, networking, appointment making and the newest food safety solutions in the industry."
The Summit will start on Monday, October 19 with an opening session on COVID-19: The New Normal for the Food Industry and will offer four days of educational sessions along with presentations from exhibitors in the Solutions Stage and Tech Tent as well as networking with attendees.
The education program will offer four 2-hour workshops and 21 one hour sessions as well as a four general sessions including the Keynote presentation by Will Daniels, President, Produce Division, IEH Laboratories and Consulting Group who will discuss Back to Basics: Consumer Focused Food Safety. In addition, the Summits annual Town Hall discussion with leaders from the FDA, AFDO, CDC and USDA and a general session focused on Foodborne Illness Outbreak Mock Criminal Trial - A View from the Jury Box featuring Shawn Stevens, Food Industry Counsel LLC, will be offered.