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Mosquito Fungus Amongus, Novel Trapping Devices for Bed Bug Surveilance, and Bed Bug Histamines

Fairfax, VA – June 1, 2025

In this episode, the NPMA team presents on new research highlighting transgenic mosquito fungi, how some plants can be used to monitor for bed bugs, and the stability of bed bug excreted histamines. We're joined by special guests Courtney and Adam Carace with Pest-End. 

Featured Article Summaries

Mosquito Fungus Amongus

Transmission of Transgenic Mosquito-killing Fungi during Copulation   

There is a humungous fungus among us! …. Or soon to be. At least for mosquitoes.  

Entomopathogenic fungi, or fungi that are pathogenic to insects and other arthropods are a relatively recent introduction to pest management. Currently the most well-known entomopathogenic fungus that is currently on the market both in the agricultural and structural fields is Beuvaria bassiana, which causes White Muscardine Disease. According to the database EntomoFun 1.01, there are over 370 entomopathogenic fungi that are known to affect arthropods. Which begs the question: are we using all the fungal tools available in the integrated pest management toolbox? 

Introducing the fungus Metarhizium pingshaense, which is one of the many entomopathogenic fungi out in the world. To beef up the mortality potential, the researchers developed a transgenic, or genetically modified, fungus that feature genes that code for the neurotoxin in the venom of Australian funnel-web spiders. Previous studies demonstrated a 99% knockdown of mosquito populations when the mosquitoes came into direct contact with the spores. However, as we well know, different mosquitoes even within the same species have different resting behaviors, and some species may not encounter the spores directly. 

Enter the good ol’ birds and the bees. Well, the fungus and the mosquitoes in this case. The researchers used field-collected Anopheles colluzzii, a major vector of malaria that is known to show resistance to multiple pesticides. In both laboratory and semi-field experiments, meaning that the mosquitoes were exposed to a mock village outside within a netted environment, researchers tested whether this transgenic fungus could be passed on through mating encounters, and if it could be a successful means of mosquito management. 

The first experiment evaluated female survival after mating with males infected with the transgenic fungus, and the fungus that was typically found in the wild, or the wild-type. After 14 days, an average of 68% of females died following mating with males that featured the wild-type fungus, and an average of 89.33% of the females died following mating with males that featured the transgenic fungus. Female Anopheles colluzzii typically begin to lay eggs a few days post-mating and blood feed. Therefore, the fungus has the potential to not only kill off the females, but disrupt egg production. In addition, the males that featured the transgenic fungus remained infectious for up to 24 hours, meaning that multiple mates could potentially be infected. However, after 48 hours, the male mosquitoes begin to succumb to the effects of the fungus as well.  

In the semi-field experiments, both male and female mosquitoes were released into a netted outdoor environment, again with the males being infected. This time, the fungus was tagged with a fluorescent marker for the researchers to determine the exact spread of the pathogenic fungus throughout their “mini-colony”. They found that female morality closely matched the estimated mating rates, meaning that every female that mated was brought to an early end thanks to the sexually-transmitted fungus.  

While Sterile Insect Technique is not a new kid on the block, a sexually transmitted fungus is. Sterile Insect Techniques are those where sterile males are released into the environment to mate with wild females. However, few of these techniques additionally affect adults, which is what makes this fungus so special. With the potential to affect multiple species, this fungus, which affects not only the adults, but the next generation by potentially disrupting egg production, could be an awesome breakthrough in mosquito management. While there is much more research to go on this front, it not only provides a potential window for further understanding mosquito mating behavior, but also a potential new weapon in the battle against the number one public health pest.  

Article by Laura Rosenwald, BCE

References

Bilgo, E., Lovett, B., Millogo, A.S. et al. Transmission of transgenic mosquito-killing fungi during copulation. Sci Rep 15, 2181 (2025). https://doi.org/10.1038/s41598-024-83242-5

  1. De Wint, F.C., Nicholson, S., Koid, Q.Q. et al. Introducing a global database of entomopathogenic fungi and their host associations. Sci Data 11, 1418 (2024). https://doi.org/10.1038/s41597-024-04103-4
  2. Image: Locusts affected by Metarhizium spp. source: CSRIO

Novel Trapping Devices for Bed Bug Surveilance

A Novel Leaf-Derived Trapping Material Is More Effective at Capturing Common Bed Bugs (Hemiptera: Cimicidae) than Selected Commercial Monitoring Devices   

Just like an episode of Wipeout, bed bug traps do their best to thwart the efforts of bed bugs to get where they want to go. This article looked at some new innovations in physical bed bug trapping. 

Detecting and monitoring bed bug infestations is critical for all sorts of customers both residential and commercial. This study looked at the traps used for such monitoring to see how effective they were and proposed a new idea for a trap design.  

Early detection of bed bug infestations or reinfestations is critical to a successful management plan and is the start in turning the bed bugs, into dead bugs.  Many IPM plans utilize different types of traps to catch bed bugs such as pitfall or sticky cards. Sticky cards are one you are probably very familiar with where the bug is caught in a sticky material on a piece of cardboard or paper.  In this experiment they used both open and folded traps. Pitfall traps are the kind where the bug walks over it then falls to their doom and cannot get back out. Typically, these pitfall traps work better for bed bugs. The one they used in the experiment was volcano brand. 

Currently, pest control companies use either type despite pitfalls being generally more effective. Sticky traps are less expensive and require less frequent checks. The researchers took a look at different cultural practices around the world to gain ideas on what to try next. Southeastern europeans used common bean leaves, (that’s kidney beans as you may be more familiar with.) The leaves were treated to preserve them and their bug trapping qualities. They were then glued flat to a surface for testing. Basically, the leaves have fuzz on them that traps the bed bugs little feet and keeps them there to eventually die. Check out how the leaf hairs can trap bed bugs.  

They called this the leaf derived trapping material or ldtm. In the setup they had an arena with bed bugs placed in the center. They put the ldtm in two corners and one of the other commercial traps in the other two corners. They also shaded the corners to replicate the environment that the traps would be underneath something.  They released bed bugs of both sexes and varying ages from nymph to adult in these arenas and then assessed the findings after 24 hours, seeing how many bugs and of what demographic had fallen into these various traps.  

Here’s what they found. The leaf derived traps outperformed the other trap types by quite a margin.  A key point was that more of the bed bugs interacted with the leaf material, more gave it a try, than they did with the other sticky or pitfall traps. It is also important to note that these traps were compared over 24  hours and other styles have previously been compared over a longer time frame of several days to several weeks. The researchers also observed that the leaf material was better at catching nymphs, the younger bed bugs, and that accounted for a lot of the differences. Nymphs make up a majority of the bed bug population by numbers so catching them would be just as important as the adults if not more. This proof of concept shows that indeed, the ldtm is effective in the short term and is certainly worth testing over a longer period of time to ensure effectiveness longer term.  So, in the end, in our gameshow of bug antics, the young guns were overtaken by the newest obstacle.  

Article by Ellie Sanders, BCE

References

Bustamante, J., Jr., Liu, P., Campbell, K., Sutherland, A. M., Choe, D.-H., & Loudon, C. (2025). A Novel Leaf-Derived Trapping Material Is More Effective at Capturing Common Bed Bugs (Hemiptera: Cimicidae) than Selected Commercial Monitoring Devices. Insects, 16(4), 362. https://doi.org/10.3390/insects16040362

Bed Bug Histamines

Effects of Aging and Cleaning on Bed Bug (Hemiptera: Cimicidae)-Derived Histamine 

The common bed bug is a notorious pest known for its thirst for human blood. But, despite its vampiric nature, this insect doesn’t vector dangerous pathogens, so it’s often overlooked as a serious health threat. But, for the past few years, Dr. Zach Devries and his team at the University of Kentucky have been working to better understand how chronic exposure to bed bug infestations could threaten public health.  

It’s well documented that cockroach saliva, feces, and caste skins contain harmful allergens that can accumulate in the environment. Repeated exposure to these allergens can lead to respiratory illness and other serious negative health outcomes. Much like cockroaches, bed bugs also leave behind feces and shed skins that can accumulate over time during an infestation. But, up until a few years ago, it wasn’t exactly clear what effects, if any, a bed bug infestation may have on an indoor environment. Thanks to Dr. DeVries, we have some answers. 

Past studies led by DeVries and his team have demonstrated that bed bugs excrete histamines that can accumulate in an environment during an infestation. Importantly, unlike cockroach allergens that decline in the environment over time after a cockroach infestation is resolved, bed bug histamines persist in the environment for months. Even after a bed bug problem has been resolved. Research is still ongoing to fully understand exactly what chronic exposure to these histamines means for public health, but exposure to histamines generally isn’t ever a good thing so it’s widely assumed that chronic exposure to bed bug excreted histamines isn’t translating improving health.  

In the most recent study out of the DeVries lab led by Simona Principato, the team wanted to further explore the stability of bed bug excreted histamines in the environment and what effects mitigation measures such as cleaning and pest control treatments would have on histamine levels. To do so, they first measured histamine levels on two different surfaces (unfinished wood and fabric) over 9 months in the laboratory. They found that there was no significant difference in histamine levels over the 9-month period on either surface.  

In a second experiment, Principato measured the effects of multiple cleaners and treatments on histamine levels using the same unfinished wood and fabric surfaces. The cleaning treatments included soft cleaning, deep cleaning, a laundry cycle, steaming, and vacuuming. Soft cleaning involved using a paper towel saturated with a cleaning solution of either water, vinegar, bleach, enzyme cleaner, steri-fab, hydrogen peroxide, or a multi-purpose cleaner. The paper towel was forcibly rubbed on bed-bug-exposed surface 3 times. The deep cleaning method was similar to soft cleaning, but the process involved forcibly rubbing the surface 30 times which equated to a 10x increase in rubbing.  

What Principato found in the second study was that cleaning using bleach, hydrogen peroxide, and a laundry cycle were the most effective cleaning methods at reducing histamines on fabric. On the unfinished wood surface, a multipurpose cleaner, bleach, and hydrogen peroxide were the most effective cleaning methods. For all cleaning types and surfaces, only bleach and hydrogen peroxide reduced histamine levels below detectible levels. Interestingly, pest control interventions using heat or a pesticide (Demand) did not significantly reduce the amount of histamine on either surface.   

Collectively, this study demonstrated that bed bug excreted histamines are incredibly stable and will be slow to degrade naturally. And, that some level of cleaning intervention is required to mitigate residual histamines left behind by these blood sucking pests.  

What this means for pest management professionals as protectors of public health is that the job isn’t over when all the bed bugs in a structure are dead. The blood spots and cast skins left behind in the infestation all contain histamines that contaminate the indoor environment. Additional sanitation measures to remove dead bugs and cast skins as well as residual fecal spots will need to be implemented, either by you or the homeowner, to restore the health of the indoor environment to pre-infestation levels

Article by Mike Bentley, PhD, BCE

References

Principato S, DeVries ZC. Effects of aging and cleaning on bed bug (Hemiptera: Cimicidae)-derived histamine. J Med Entomol. 2025 May 13;62(3):495-500. doi: 10.1093/jme/tjaf042. PMID: 40221908; PMCID: PMC12076141. 

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