Date of Award
Honors College Thesis
Marine Biology BS
Kaitlin Baudier, Ph.D.
Mischocyttarus mexicanus is a species of eusocial paper wasp that is found across much of the Southeastern coastal region of the United States. Contrasting wintering strategies have been seen in northern versus southern populations. Anecdotally, northern populations overwinter by clustering on top of palmetto fronds, their preferred nesting substrate, in a sort of "taco" shape, while southern populations stand on their nests that hang on the underside of the palmetto frond throughout the year. I tested three hypotheses related to the adaptive value of northern over-frond clustering behavior: 1) Over-frond clustering is thermoregulation related, meaning it would be temperature driven. 2) Clustering on top of fronds provides protection from nests falling more often in the winter. 3) Clustering on top of fronds prevents wasps from losing grip on the underside nesting substrates due to cold immobility. To test these hypotheses, I placed iButton temperature probes on the top and underside of M. mexicanus nesting fronds in Louisiana and Mississippi during the winter (the southern range limit for overwintering clustering behavior). I also performed nest falling surveys across seasons. Lastly, I compared ambient temperatures to the temperature at which this species loses motor control (CTmin). Results suggested that this behavior was not thermoregulatory. I did, however, find that nests had a higher probability of falling in the winter than warmer ones, which supports the hypothesis of protection from nest falling. Lastly, ambient temperatures in the winter dropped below CTmin, suggesting that wasps cluster on top of fronds during cold winters to prevent falling off of nests due to cold coma. This could allow us an explanation of the change in behavior of the northern populations, as temperatures more often reach cold enough values to hinder mobility significantly. Compared to other eusocial insects, even being native to Mississippi, Mischocyttarus mexicanus has not been heavily researched in the past, which our research findings hope to help rectify. Also, by understanding climate impacts on certain species, we can understand the connection between animal physiology and changing climate.
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Guild, Taylor, "Variations in Thermoregulation Strategies of Northern and Southern Populations of Mischocyttarus mexicanus" (2023). Honors Theses. 940.