Pestology Blog
Cockroach Gel Baits, Termite Corpses, and Highly Pathogenic Avian Influenza
Fairfax, VA – May 1, 2025
In this episode, the NPMA team discusses new research on consumer and professional grade cockroach baits, what termite corpse management means for termiticide performance, and insights into the USDA's dataset on Highly Pathogenic Avian Influenza. We're joined by two special guests, Adam Brashier and Del Lawson of Modern Pest Control!
Featured Article Summaries
Termite Corpse Management
The Impact of Termiticides on Termite Corpse Management
Termites are some of the most destructive pests against property that we manage as pest management professionals. Recent estimates suggest that termites cause up to $6.8 billion dollars in damage in the United States alone each year. Luckily for us, there are several products on the market that feature several different active ingredients that can be applied in different ways. But given the intricate ways that termites can interact with each other in their colonies, it brings up several questions about how these termites may be responding to the treatments that we are throwing their way.
This study exposed Reticulitermes flavipes, or the Eastern Subterranean Termite to several different chemical control strategies, including both soil treatments and baiting. The repellent termiticide included bifenthrin, the non-repellent termiticides included fipronil, imidacloprid, chlorantraniliprole, and chlorfenapyr. The baits included hexaflumuron, and sulfluramid. The researchers then examined the death-related chemicals released by termites who succumbed to these various active ingredients and examined the behavioral responses of the live termites to the corpses.
The release of the death-related chemicals differed immensely based on what termiticide the termites were treated with. Those that were treated with bifenthrin and fipronil featured spikes of “early death cues”, which included 3-octanol and 3-octanone. Despite these early spikes, these cues rapidly dropped off after about 2 hours. All the other termiticides tested featured gradual release of these same early death cues. However, interestingly, there was no difference noted between the late death cues, which were phenol, indole, and oelic acid, across the different termiticides.
However, when the researchers compared the use of the active ingredients in baiting devices versus soil treatments, there was no obvious difference in how the termites reacted to the bodies. Typical termite behavior in undertaking duties normally involves retrieving the corpse to bring back to the main nest to eventually cannibalize, or eat the body of the dead worker. In other words, the researchers observed that termite workers still performed their undertaking duties despite the treatments that were being applied, except for bifenthrin.
The early death cues, or 3-octanol and 3-octanone, are often what triggers the other individuals in the colony to address the body in the room. However, as we mentioned, this study found that those termites treated with bifenthrin and fipronil saw a high spike of these early death cues. As a result, workers were more likely to “wall-off” or close the tunnel to the body for those treated with bifenthrin. Bifenthrin acts as a repellant, so it makes sense that the termite workers wanted to just hold the funeral and be done. However, with the fipronil-treated corpses, workers responded to those treated with fipronil by eventually retrieving them but with a distinct delay. One of the theories for this delay with fipronil points to behavioral resistance, as fipronil is known to induce immobilization, where the termites remain alive, but unable to move. This immobilization and delay in undertaking of these fipronil-killed corpses may result in the accumulation of corpses in treated areas, thus leading to the healthy termites avoiding that area. Therefore, termite response time differed for fipronil, but the termite workers overall still performed their undertaking behaviors as expected.
Despite the differences in the chemical cues released by termites who were killed by these termiticides, there were generally little differences in the behavioral response to the corpses by the still-healthy workers. Understanding undertaking behavior in termites is crucial, as it can dictate the effectiveness of the product. The clean-up and potential cannibalization of the corpse has the potential to pass the product on to the next individual in the colony, which highlights how important it is to consider how these pests are interacting with the products that we use. Overall, this study highlights that while termiticides can influence termite behavior, it is not the only factor that termites use to implement undertaking behavior. More research is needed to understand these cues that dictate these behaviors, but this is a great first step in making the products that we use more effective.
Article by Laura Rosenwald, BCE
References
Shi, J., Merchant, A., & Zhou, X. (2025). The Impact of Termiticides on Termite Corpse Management. Insects, 16(2), 208. https://doi.org/10.3390/insects16020208
Cockroach baits
Laboratory and In-home Evaluations of Consumer- and Professional-grade Cockroach Baits
A few months ago, I covered a similar article that looked at residual insecticides for consumers. This article takes the findings a step further and looks into baits and their efficacy against German cockroaches.
German cockroaches are a pest we are all very familiar with. They are a threat to public health through their effects both physically and psychologically. There is lots of research that goes into detail about the allergens that can occur with German cockroach presence as well as the diseases they can mechanically vector to humans they live nearby.
Based on this and the general consensus of how unliked they are, the need to get rid of them is clear. Consumers may attack their cockroach infestations on their own before calling a pest management professional. There are many different products available off the shelf for consumers to use in their homes. While all these products claim to be effective against pests of course, the researchers here decided to put them to the test. How well would these products work compared to the products that professionals have at their disposal?
The baits tested were gel bait formulations which had different active ingredients including dinotefuran, fipronil, indoxacarb, clothianidin, pyriproxyfen for anyone who happens to be interested. The brands you may know these consumer available baits as are: combat gel bait, combat bait stations, and hot shot liquid bait stations. The professional grade products you may recognize are Vendetta Nitro, Advion Evolution, and Maxforce FC Magnum.
This study used a few different cockroach populations to test. They took some from a known susceptible strain called Orlando normal, as well as 8 different populations from actual apartments aka the real world that probably have some resistance going on. For the in-lab studies, they took cockroaches and starved them for 24 hours before exposing them to the bait. The gel baits used 500mg of each placed with the roaches, and the containerized products were placed one with the roaches. They also made sure to use only male roaches in this part as they feed more regularly and do not experience the same physiological fluctuations as females might.
The in-home part was set up in actual homes with voluntary participants. They found 32 homes to take part. These were apartments from 1-3 bedrooms within apartment buildings. The study took place over 5 months with multiple evaluations during that time. They applied the baits according to label instructions for both consumer and professional grade. The professional grade application used multiple different baits applied at different times over the course of treatment. Replicating what an actual PMP would be able to do. Sticky traps were used to measure cockroach populations throughout this study to show them as staying the same, increasing, or decreasing.
They found that all baits both consumer and professional grade showed some efficacy, meaning anything is better than nothing, and the treatments vs control made a difference. Amongst the consumer vs professional, they found in-lab efficacy of more than 80% mortality over 14 days against home collected roaches in all cases. However, the in-home efficacy of the consumer baits was inconsistent with the in-lab findings.
The in-home studies used average number of cockroaches per day as their efficacy metric since they could not track every roach. The professional gel bait staggered application resulted in far fewer cockroaches per day than the hot shot, combat, or containerized stations. The most effective consumer option was the Hot Shot containerized bait stations.
So, what does this all mean? The findings of this experiment corroborate those of the previous one. It seems to be the case that consumer available products may pass tests in the lab and are therefore allowed to be marketed as they are, however they do not do the job as needed in the home aka real life. Key takeaways are that as we expected, that professionally grade products and professional application beat out the consumer available options. While using consumer available products may be cheaper in the short term, they are ultimately less effective. The moral of the story here is don’t try to DIY, call a pro.
Article by Ellie Sanders, BCE
References
Johnalyn M Gordon, Angela J Sierras, Daniela V Jackson, Simona Principato, Zachary C DeVries, Laboratory and in-home evaluations of consumer- and professional-grade cockroach baits, Journal of Economic Entomology, 2025;, toae291, https://doi.org/10.1093/jee/toae291
APHIS Data on Avian Flu in Mammals
USDA’s APHIS Report - Detections of Highly Pathogenic Avian Influenza in Mammals
The USDA’s Animal and Plant Health Inspection Service, also known as APHIS, is an important agency responsible for a long list of programs and activities that all aim to protect animal health, animal welfare, and plant health in the US. Among those essential programs is the agency’s role in animal disease surveillance and reporting. The critical need for this service has been underscored over the past few months as APHIS has provided transmission data and directed response efforts for combating the spread of the H51N1 strain of highly pathogenic avian influenza (HPAI) that has been devastating US poultry and dairy farms. One of the agency’s surveillance reports recently made national news after it published findings that 4 black rats (Rattus rattus), also known as roof rats, tested positive for the virus in Riverside County, California. The concern here was that roof rats could serve as a new pathway of exposure for the virus that may put more animals, pets, and people at risk. Given the potential implications for these findings, I wanted to dive into the USDA’s report to talk about what the data showed, what we know about rodents and avian flu, and what we don’t yet know about the implication of these reports.
I’m an entomologist not a virologist so I’m not going to get into the weeds on avian flu and how it works, but it is worth a quick review of the virus so we’re all on the same page. Avian influenza, AKA “bird flu,” is a contagious disease spread among wild and domestic birds and is generally divided into two categories: low pathogenic and highly pathogenic avian influenza. The low pathogenic variant occurs naturally in wild birds and can impact poultry, but it doesn’t typically kill these birds the same way the highly pathogenic strain does. As a result, some control options are available beyond depopulation. The highly pathogenic strain, however, is far more lethal and depopulation is required to stop its spread.
In February 2025, the APHIS report, Detections of Highly Pathogenic Avian Influenza in Mammals, published that 4 black rats tested positive for HPAI. The roof rat data was notable because this was the first detection of HPAI in rats since 2021. The broader concerns from these findings were that roof rats commonly enter structures and farms, and that infected rats could increase the transmission risk of this virus where infestations occurred.
This transmission risk is based on the assumption that infected rats could competently spread the virus to others. But, are roof rats competent vectors of the disease? Some articles discussing the transmission risk of roof rats cited a study published in 2024 that tested the susceptibility of the roof rat (Rattus ratus), the Norway rat (Rattus norvegicus) and the house mouse (Mus musculus) to HPAI. The purpose of this study was to measure the rodent’s vulnerability to HPAI infection. The researchers exposed the rodents to the virus via intranasal inoculation and collected oral and rectal samples over several days. They found that virus could be recovered from oral swabs several days after infection, while little to no virus was recovered from fecal or rectal swabs. The infected rodents were later dissected and HPAI was also detected in respiratory tract tissues. From these data, the authors concluded that the rodents are susceptible to the virus and that infected rodents could contaminate food, water, and the environment in poultry facilities.
What these researchers showed in this study was important. But what they DIDN’T show is equally important. The study confirmed that virus could be recovered from infected rodents, but it didn’t actually demonstrate transmission from rodents to other individuals. And, that’s an important factor in the broader picture. I’m not pointing this out to discredit or take away from the importance of the study, because their findings are impactful. But, a lot of variables go into making something a good vector of a disease, and it’s important to note that transmission wasn’t demonstrated in that publication. That’s not to say that a future study won’t show this, but we didn’t get that result from this study here.
It may sound like I’m trying to make the case that rodents aren’t a concern when it comes to HPAI, which I’m not. And I’m not suggesting in any way that media reports were not correct in suggesting that roof rats could be a concerning new pathway for exposure for HPAI. Because they could be. I’m only pointing out a hole we have in published data that we need to fill to complete the picture.
I want to go back to the APHIS data because there is a lot of information from these detections that haven’t been talked about much. And, that’s the other mammals that have tested positive. As of April 1, 2025 the APHIS report returned 591 positive tests from 44 different mammals. House cats topped the list, with 130 positive detections, while house mice ranking third with 97 positive detections. That’s 16% of the total data pool. And, deer mice weren’t far behind in 6th place, with 27 positive detections representing 5% of the total data pool. Roof rats made headlines, but they only represented 1% of the total counts of positive results. Roof rats, Norway rats, and house mice were all tested in the previously mentioned study, demonstrating their susceptibility to HPAI. And, house mice are a common pest of dairy farms.
So where am I going with all this? I think we may not have enough data yet to confirm the exact role that these rodents play in spreading HPAI. But collectively, what this information does is further underscore the public health concerns of these rodents as a whole. HPAI isn’t the only pathogen rats and mice are susceptible to, and we have decades of hard data to show the risk they pose to food and public health from the dozens of other diseases they can spread. Their potential to vector yet another dangerous disease is just another reason why professional pest management is so important, and why our access to all the tools in the PMP tool belt are needed to allow us to respond quickly and safely when the need arises.
Listen to the Episode!
Have questions or feedback for the BugBytes team? Email us at training@pestworld.org, we'd love to hear from you!
