Study Highlights Diversity of Arthropods

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Distribution of dust mites detected in door trim dust from inside homes across the United States (purple) compared with the range where they are predicted to be most abundant (tan). Image credit: Anne A. Madden.

Researchers from North Carolina State University and the University of Colorado Boulder used DNA testing and citizen science to create an “atlas” that shows the range and diversity of arthropods found in homes across the continental United States.

Scanning electron micrograph of home dust including dust mites, animal fur, fibers, and pollen. Image credit: Anne A. Madden, with the assistance from Robert Mcgugan at the University of Colorado, Boulder Nanomaterials Characterization Facility. False-coloring done by Robin Hacker-Cary. Click to enlarge.Scanning electron micrograph of home dust including dust mites, animal fur, fibers, and pollen. Image credit: Anne A. Madden, with the assistance from Robert Mcgugan at the University of Colorado, Boulder Nanomaterials Characterization Facility. False-coloring done by Robin Hacker-Cary. Click to enlarge.

Previous research found a significant diversity of arthropods in homes in one part of North Carolina – we wanted to use advanced DNA sequencing-based approaches to get a snapshot of arthropod diversity in homes across the country,” says Anne Madden, a postdoctoral researcher at NC State and lead author of a paper on the new work. “This work is a significant step toward understanding the ecology of our own homes, with the goal of improving our understanding of how those organisms in our homes may affect our health and quality of life.”

To collect nationwide data, the researchers recruited more than 700 households across all 48 states in the continental United States. Study participants swabbed dust from the top of a doorway inside their house or apartment. The swab was then sealed and sent to the research team, which used high-throughput DNA analysis to identify every genus of arthropod DNA found in the dust samples.

“We found more than 600 genera of arthropods represented inside people’s homes – not including food species, such as crabs and shrimp, which also showed up,” Madden says. “That’s an incredible range of diversity from just a tiny swab of house dust.”

After analyzing the data, researchers identified several variables that were associated with greater arthropod diversity: having cats or dogs in the home; having a home in a rural area; or having a home with a basement.

“Greater diversity does not necessarily mean greater abundance,” Madden says. “We’re talking about more types of arthropods, not necessarily larger populations of arthropods.”

Researcher Anne Madden, looking at trays of samples containing DNA samples from homes. Image Credit: Adrianne A. Madden.
Researcher Anne Madden, looking at trays of samples containing DNA samples from homes. Image Credit: Adrianne A. Madden.

These findings expand on previous work that found pet ownership also increased the biodiversity of microbial organisms, such as bacteria and fungi.

“We were surprised to see that these three variables – which we have some control over – were more powerful predictors of biodiversity than climate,” Madden says. “We had expected environmental factors associated with regional climate to play a larger role than they actually did.”

However, the scope of the study data also allowed the researchers to create a national atlas they can use to track the range of specific arthropod genera. And, depending on the genus, climate factors were seen to play a significant role in determining the range of some arthropods.

For example, dust mites can be serious allergens in homes and the team found that they were more often associated with homes in humid regions of the country.

In addition, researchers were able to use the atlas to identify genera that had significantly expanded their range – but no one had previously noticed.

For example, the Turkestan cockroach (Shelfordella lateralis) was previously thought to be found only in the southern and western regions of the United States – but the data from this study showed that it had expanded as far as the Northeast.

“We’re just scratching the surface of how we can use this data set and the arthropod atlas,” Madden says. “What can it tell us about the food webs in our own homes? What can it tell us about how arthropod populations expand and contract across the country? What emerging allergens can it reveal? We’re just getting started.

“Also, we want to stress that this was a citizen science project,” Madden says. “This study would not have been possible without the participation of people from across the country who volunteered to be actively involved in the work.” [Note: anyone interested in participating in future citizen science projects with this research team can visit]

The paper, “The diversity of arthropods in homes across the United States as determined by environmental DNA analyses,” is published in the journal Molecular Ecology. The paper was co-authored by Albert Barberán and Noah Fierer of the University of Colorado Boulder; Matthew Bertone and Holly Menninger of NC State; and Rob Dunn of NC State and the University of Copenhagen. The work was done with support from the Alfred P. Sloan Foundation.

Note to Editors: The study abstract follows.

“The diversity of arthropods in homes across the United States as determined by environmental DNA analyses”

Authors: Anne Madden, North Carolina State University and University of Colorado, Boulder; Albert Barberán and Noah Fierer, University of Colorado, Boulder; Matthew A. Bertone and Holly L. Menninger, North Carolina State University; Robert R. Dunn, North Carolina State University and University of Copenhagen

Published: Nov. 1, Molecular Ecology DOI: 10.1111/mec.13900

Abstract: We spend most of our lives inside homes, surrounded by 3 arthropods that impact our property as pests and our health as disease vectors and producers of sensitizing allergens. Despite their relevance to human health and well-being, we know relatively little about the arthropods that exist in our homes and the factors structuring their diversity. Since previous work has been limited in scale by the costs and time associated with collecting arthropods and the subsequent morphological identification we used a DNA-based method for investigating the arthropod diversity in homes via high-throughput marker gene sequencing of home dust. Settled dust samples were collected by citizen scientists from both inside and outside more than 700 homes across the United States, yielding the first continental-scale estimates of arthropod diversity associated with our residences. We were able to document food webs and previously unknown geographic distributions of diverse arthropods—from allergen producers to invasive species and nuisance pests. Home characteristics, including the presence of basements, home occupants, and surrounding land-use, were more useful than climate parameters at predicting arthropod diversity in homes. These non-invasive, scalable tools and resultant findings not only provide the first continental-scale maps of household arthropod diversity, our analyses also provide valuable baseline information on arthropod allergen exposures and the distributions of invasive pests inside homes.

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Ants Need Work-Life Balance

By | Carpenter Ants, Fire Ants, Pests | No Comments
Credit: © corlaffra / Fotolia

Credit: © corlaffra / Fotolia

As humans, we constantly strive for a good work-life balance. New findings by researchers at Missouri University of Science and Technology suggest that ants, long perceived as the workaholics of the insect world, do the same. In fact, according to these researchers, it is imperative that some ants rest while others work to conserve food, energy and resources for the colony. And the larger the colony, the more important this work-rest balance becomes.

“It has been a long-standing question in the field as to why large colonies of ants use less per-capita energy than small colonies,” says Dr. Chen Hou, assistant professor of biological sciences at Missouri S&T and research team lead. “In this work, we found that this is because in large colonies, there are relatively more ‘lazy workers,’ who don’t move around, and therefore don’t consume energy.

“We found that the portion of inactive members of a group increases in a regular pattern with the group size,” Hou says.

The research team consistently observed that 60 percent of workers were not moving around in a 30-ant group, whereas this percentage increased to 80 percent when the group size increased to 300 ants.

“The simultaneous energetic measurements showed that the per capita energy consumption in the 300-ant group is only 50 percent of that in the 30-ant group,” Hou says.

By not consuming energy, these “lazy” ants are actually saving resources for the colony and making the colony more productive.

This realization could provide valuable insight into making our societies more productive and sustainable.

“Humans are like ants in a way that we all live together in groups, collaborating toward our own betterment,” Hou says. “Both humans and ants face similar problems of allocating resources based on tasks and energy. Understanding how ants spend their energy in relation to their group and why they do so will provide insight into conditions for individuals that allow a group to perform collective optimization of behavior, that is, in the context of sustainable use of scarce resources.”

Hou and his team, which includes two undergraduate Missouri S&T students, discuss their findings in a forthcoming issue of the journal Insect Science.

“Maximizing resource acquisition would require most individuals to be highly active, but would also result in high energy expenditure and long average foraging time. In contrast, minimizing time and energy expenditure would require most individuals to be inactive, but would also result in low resource acquisition,” Hou says. “Thus, we postulate that ant colonies balance these two optimization rules by the coordination of the forager’s interaction.”

Hou says his team came to its conclusion using a state-of-the-art computerized vision analysis program to track the motion trajectories of ants. His colleague, Dr. Zhaozheng Yin, assistant professor and Daniel C. St. Clair Fellow of computer science at Missouri S&T, developed the program.

Using Yin’s automatic algorithm, the research team was able to analyze the movements of ants over longer periods of time and higher temporal resolution than had ever previously been conducted. Previous studies had only analyzed the movements of ants in minute-long intervals. The analysis of a two-hour-long video by the research team showed a large variation in the average walking speed of ants in the colony, from .2 centimeters a second to 1.4 centimeters a second.

“This indicates it is likely that the analyses of one-minute observations give only momentary snapshots, and may not well represent the ants’ behaviors over long periods,” says Hou. “These comparisons highlight the advantage of our automatic computerized tracking technique, because it is difficult, if not possible, to manually digitize coordinates of individual ants with high temporal resolution over a long period.”

By tracking ants’ walking behaviors over longer periods of time, the researchers also determined how much energy ants consume while working as opposed to resting.

“We found that walking ants consume five times more energy than resting ants,” says Hou. “This means that energy wise, one walking ant is equivalent to five resting ants. Thus, if a group has 20 percent active members, this group would consume 180 percent more energy than a similar sized group with all inactive members.”

The research team, which also includes sophomore Nolan Ferral and junior Kyara Holloway, both biological sciences majors at Missouri S&T, and Mingzhong Li, a Ph.D. student in computer science, shared its findings in an article titled “Heterogeneous activity causes a nonlinear increase in the group energy use of ant workers isolated from queen and brood.” The article will be published in an upcoming issue of Insect Science.

“It is intuitive that colonies have inactive members, because these members may serve a backup role or buffer, which would be activated when colonies are under stress, such as an urgent need for nest maintenance or defense,” says Hou. “But it is unclear why the proportion of the inactive members is not a constant — why larger colonies have relatively more ‘lazy’ workers. Thus, our study calls for future research on ant interaction networking and behaviors.”

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The Truth About Carpenter Ant Swarms

By | Carpenter Ants, Pests | No Comments

Reproductive CAThe Pacific Northwest climate is well suited for carpenter ants.  It is not surprising that these wood nesting ants are the number one structural wood destroying insect pest in Washington State. 

So how concerned should home owners be when they see these large winged creatures each spring invading their property?

Mature carpenter ant colonies have a main nest and one or more associated satellite nests. Main nests can be found in living conifer trees, stumps, landscape timbers, firewood, and most any sizable wood debris in contact with the soil. Main nests need wood with a high moisture content to survive.  In contrast, Satellite nests can utilize dry wood such as the timbers of a structure. Most homes damaged by carpenter ants are a result of infestation by satellite nests.

Each spring, mature colonies send out thousands of new queen ants in swarms to establish new main nests.  These black swarming ants, sometimes one inch in length, are called reproductives; they fly short distances before losing their wings and begin wandering for new homes.  Only a small fraction of these winged reproductive ants survive to create new colonies. 

Since these budding queens need wood with high moisture content, most well-maintained homes due not fulfill the moisture needs and are therefore not capable of being a main nesting site.  In April and May, homeowners should not be overly alarmed when observing these large ants crawling in the landscape or occasionally in the house, especially if your home is routinely serviced for pest prevention.


In contrast, if you observe large numbers of winged ants clustering together inside your home or smaller, wingless black ants trailing in regular patterns inside or outside of your home, this may indicate an established carpenter ant satellite nest in the home, requiring an inspection by a qualified licensed pest management professional.

For those without regular pest control service, the month of May is an excellent time for an annual

Get Rid of Flies

By | DIY, Flies, Pests | No Comments

The key is proper sanitation and housekeeping to control flies. Following these following steps will help you limit and control flies.

  1. Remove garbage at least 3 times per week.
  2. Get garbage cans with tightly fitted lids.
  3. Keep garbage cans as far away from doors and windows as possible.
  4. Keep doors and windows closed or properly screened.
  5. Pick up animal droppings.
  6. Remove dead animals or birds that have died in or around your home, walls and attic.
  7. Keep exposed food covered.
  8. Do not over water houseplants.
  9. Clean up under tables and hard to reach areas.
  10. Unclog all drains.
  11. Use fly traps, sprays or baits to kill and control flies indoors.

If you have tried these steps and still have a problem, contact Pratt Pest Management today!

Tips on Spider Prevention

By | Pests, Spiders | No Comments

To help prevent spider nesting around your house:

  • Keep firewood and logs away from the home.
  • Clean up leaves and other organic debris from around your yard.
  • Trim back any trees and shrubs that contact the home.
  • Caulk/Seal cracks and gaps in the home’s structure, foundations, doors and windows.
  • Indoors, spiders can be prevented by frequent vacuuming and sweeping of corners, closets, basements and other out-of-the-way places.
  • When vacuuming, sweeping or otherwise removing webs, be sure that all egg sacs are captured as well to prevent new spiders.
  • Reduce or eliminate piles of papers, boxes, bags, and other clutter to reduce potential harborage areas.

Our Four Season Protection service can help prevent spider nesting in your home. Contact us today!

Slugs and Snails, Oh My!

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snail and strawberries

In Western Washington, these seemingly ubiquitous pests are voracious feeders upon ornamental and vegetable plants. Slugs especially, are nocturnal, hiding during the day under debris, mulch and low-growing plants. At night they come out and eat plants, consuming 30-40 times their weight every day.

Slugs and snails belong to the Mollusk family and are “related” to clams, oysters, squid, and octopus. Slugs and snails move along on a muscular “foot” secreting mucus and leaving a slime trail in their wake.

These creatures are unique in that they contain both female and male reproductive systems and propagate through cross-fertilization. Slugs are capable of producing 400 offspring yearly and can have a life span of up to two years.

There are many species of slugs and snails in our environment; some are native while others are imported evasive species. In short, the “black” slugs are imported and supposedly do the most damage to plants versus the “Banana Slugs” which are more yellowish in color and are native.

Pratt Pest offers several options to rid your home and property of slugs and snails whether it is a single service or a slug and snail program with a guarantee. Call us today for a free estimate!

Featured Pest: Rodents

By | Pests, Rodents | No Comments

Baby, it’s cold outside! Those rats and mice are cold and looking for a warm place to stay and that might just be your home. Rodents carry diseases, provide unsanitary conditions, and can cause serious damage to your home. If you notice feces, burrows or holes in or around your home, scratching, or damaged insulation in the crawlspace or attic, call Pratt Pest and we will have a technician at your door ASAP!

Fire Ants Identified in Seattle

By | Fire Ants, Pests | No Comments

The European fire ant (Myrmica ruba) has recently been found to be established and thriving in Seattle. The European Fire Ant (EFA) should not be confused with the imported Fire Ant species (Solenopsis spp) that has gained such notoriety in the Southern United States yet the sting delivered is no less painful. As with other stinging insects the EFA may cause severe allergic reactions including anaphylactic shock to sensitive individuals. The EFA does not create the typical mounds of other fire ants, but rather prefers living in areas of high humidity such as soil at the base of trees and shrubbery, under logs, rocks and natural debris. Even though the EFA is thought to be currently isolated near the University of Washington Arboretum they have the potential to become a major pest in the Pacific Northwest in the years to come. European fire ant workers are reddish-brown ants about 1/5 inches long. The body is covered with fine hairs. The head and thorax are sculpted with ridges and grooves and appear somewhat dull, while the abdomen is shiny. EFA workers have two backward-pointing spines on the back of the thorax and a distinct, two-segmented pedicel or “waist.” If you suspect an infestation EFA, feel welcome to drop off a sample and we will provide a free identification from one of our two staff entomologist.