Virginia Roberts

Resource-driven control of cavity-nesting wasp densities

April 10, 2021   /  

Name: Virginia E. Roberts
Major: Biology
Minor: Earth Science
Advisors: Dr. Carlo Moreno, Dr. Jennifer Ison (second reader)

Cavity nesting wasps are contributors to ecosystem services such as pest suppression and function as important indicator species for ecological change. Previous studies have indicated bottom-up population regulation in the system, and specifically the importance of woody habitat as sources of diverse and abundant cavity-nester populations, while non-woody habitats function as diversity-abundance sinks. To better understand how local plant resources and woody habitat influence communities of cavity-nesters, six trap nests were placed throughout Wooster Memorial Park in Wooster, Ohio from August to November 2020. The impact of six potential drivers of the density of cavity-nesters which colonized these nests was quantified using linear regression and correlation analysis: local woody and nonwoody plant densities and diversity, floral cover, and deadwood density. The results of the analyses support the hypothesis that local standing deadwood drives the density of cavity nesting hymenopterans was found. Additionally, resource heterogeneity was favored over resource abundance as a driver of cavity-nester densities. In the context of global loss of deadwood, and increasing fragmentation of woody habitats, snag preservation or the construction of artificial nesting site structures may become important management practices for insect conservation in both backyard and natural area settings.

Virginia will be online to field comments on April 16:
noon-2pm EDT (PST: 9-11am, Africa/Europe: late afternoon)

28 thoughts on “Resource-driven control of cavity-nesting wasp densities”

  1. Very cool Ginny – congrats! We’ve been doing some experimental work with deadwood at Fern Valley and have found some similar results indicating the importance of deadwood as habitat/resource heterogeneity. Awesome work!

  2. This is incredible, Ginny! I like how your focus is on these particular wasps but you’re able to think ahead in terms of big-picture conservation. Also, props to you on what I assume was a very interesting data collection process. CONGRATS!

  3. Congratulations Ginny! This is such a cool study! How do you think fragmented habitats are being affected my the loss, or at least decrease, of these wasps ?

    1. Miyauna,
      It’s hard to say based on the low number of species we collected in this study. However, some species (in the same genus as our most abundant species) have been shown to be viable biological control agents and exert a strong top-down affect on their prey of choice. Based on this, I think it’s entirely possible that the loss of these predators in fragmented habitats would cause changes to the food chain which could be detrimental. Future work on how much cavity nesting wasps impact lower trophic levels would be very interesting!

  4. You did it! Congratulations, Ginny! That is amazing and really interesting findings!

    1. Thank you Dr. Sirot! I couldn’t have done it without all of your guidance throughout Junior I.S., 203, and just generally being an awesome entomology role model.

  5. Great job on the presentation Ginny. Was just wondering, is there any evidence of a nesting preference between trap nests and standing deadwood among some of the wasp species you studied? Do you think a preference could create some interesting source-sink dynamics among cavity nesting wasp populations over time?

    1. Thanks for the great question Carlo! I often wondered this myself while designing the project; if cavity nesters prefer natural sites, would more nests be observed in artificial nests where natural sites are unavailable? If so, I would expect to see the opposite of my ultimate deadwood finding, such that areas with more natural cavities would have fewer wasps making artificial nests. It would be a very interesting experiment!
      While no studies have been published specifically about the two wasp studies I observed and their preferences, there is one study in particular which found that non-native wasps were more likely than native ones to colonize artificial nests, but this study did not compare this finding to natural nesting sites, so it is difficult to draw a definitive conclusion about preference.
      With that said, this study also found that artificial nests were more likely to contain natural enemies of native bees and wasps, such that there may be a selective advantage to natural nesting sites. This might potentially influence wasps over time if they adapt to avoid the conditions that cause this.
      If you’re interested in the article here is the DOI: 10.1371/journal.pone.0122126

  6. Awesome project, Ginny! It’s so interesting to see your work presented in a different format. I’m used to reading your writing for class, so I enjoyed watching your video and learning all about wasps. Congratulations!

    1. Thanks for checking it out Ellen! It’s definitely a very different life than creative writing, but I love both!

  7. Astoundingly cool project from an astoundingly cool person! Watching you work with wasps all semester was super cool, and to see that you’ve done cool things with them is amazing!

    1. Thank you Max! I’m so glad you’ve been with me through so much of this journey.

  8. Great research project and presentation! What other nesting sites do wasps and bees use? And how to we get people to also #savethewasps ?

    1. Great Q’s Dr. Ison!

      The majority of native bees and wasps use exposed soils to build their nests, digging into the ground to build similar nests below ground. Many non-native wasps (and honeybees) are able to build nests outside of pre-existing cavities (like a honey-bee nest or a paper wasp structure). Additionally, cavity-nesting bees and wasps will nest in hollow (living!) twigs on trees and shrubs. We see ceratina bees nesting in our pruned peony stems in the spring at my parent’s house!

      To make people love wasps I think it’s important to build knowledge and empathy for these creatures. Building empathy for these animals makes the “dangerous” part of their nature more excusable. Only a few types of wasps are truly aggressive! Most wasps would rather sting something they can eat than waste their time and energy on a big human who scared or threatened them. More importantly, educating people on why predators are important to agriculture and natural areas highlights how these creatures are beneficial to us and to ecosystems as a whole. Conservation messaging could do a better job of reminding us that even the ugly, the mean, or the painful parts of nature are an essential part of a functioning whole.

  9. Amazing work Ginny! I loved the engaging presentation with all of the photos. You made this project really accessible! Congratulations on a job well done!

    1. Thank you Laney! It’s so important to make science for everyone so I’m glad to hear you say that.

  10. Hi Ginny! This sounds like a fantastic project and (as writing teacher and as a person with many scientist friends from college) a truly wonderful presentation of the experiment and the research–so clear and thorough, with great visuals and recaps and all sorts of things to make it clear and engaging. (Which isn’t surprising, given your fantastic writing craft!) I’ve always loved seeing bee hotels in parks and now I will appreciate them even more. Is this something that individuals can also do in a residential setting, or are wild settings preferable (either for the vespids or the humans)? Thanks, and congratulations!!

    1. Thanks Dr. E!

      While abundant natural settings are most important for conservation, there are a few things we can do in our backyards, or even on an apartment balcony!

      Before removing dead trees from landscaping, consult with a professional to determine if there are any risks to leaving it standing. If it’s far enough from any important structures, many trees can have their limbs removed, while leaving dead trunks standing so that they can decay more naturally, providing resources to bees and wasps as well as birds like woodpeckers!
      Where this isn’t possible, providing an artificial nesting site like a bee hotel is a great start.
      Lastly, this study supports the idea that using diverse native plants in gardens and landscaping may be helpful to insect populations.

      Here’s a link to similar recommendations and information from The Nature Conservancy:

      1. Thank you! I can say that I have seen some neighborhoods leaving trunks standing as you describe, so that’s good to know. (And then there’s the stump-table on our porch that has definitely been used as a nesting site for something(s). I’m not sure if it was a wasp species; it was very small and long and narrow, and seemed to be making multiple holes all at once, but it was cool to see it boring and then ovipositing and filling them in last summer!) I look forward to reading more.

  11. Wow, Virginia, so impressive and informative – I learned so much! It’s satisfying to know that we’ll have young adults such as yourself probing important questions our behalf in the future. And thanks for lifting up the importance of these ‘less charismatic’ insects. 🙂 Best of luck!

    1. Thank you Roger! It motivates me a lot to think about the future of insect conservation.

  12. Great job Ginny! It’s wonderful to see how all the bits and pieces you have told me about your IS have come together in a lovely polished presentation. Congratulations!

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