Tierra de Oro Laboratory

Physiology and Ecology in the Pinyon-Juniper Savanna

Category: updates

  • New Amplifier (some assembly rquired)

    As mentioned in an earlier post, the beetle ecology/physiology project has split into two separate sets of experiments. For the ecology project, I am hoping to get some good data regarding beetle abundance, seasonality and predation, but that will be the subject of other posts.

    To get a more mechanistic understanding of heat stress in the beetles, I plan to do two sets of experiments once the beetles are available later in the summer. One will be a relatively straightforward measure of the range of temperature tolerance for the stink beetles (Amphidorini) and their non-stinky mimics (Asidini).

    The other experiment will measure activity in the nervous systems of the beetles when they are under heat stress. There is considerable evidence that there is a blast of neural activity, sometimes referred to as a “spreading depolarization” when insects enter a state of paralysis known as heat coma. I would like the measure the temperature that is required for the spreading depolarization in the Amphidorini, which are relatively heat sensitive, and the Asidini, which are more resistant. The hypothesis is that it will take a higher temperature to induce spreading depolarization in the Asidini.

    To get those data, I will need an amplifier to record neural activity in the beetles. Although I could spend a few thousand dollars on a new, ready made amplifier, there are some nice DIY designs in the literature. The circuit I chose (from Land et al., 2001, J. Neurosci Meth. 106:47) should do everything I need. It can amplify signals between 100X and 1000X, it has filters to stabilize the signal and reduce noise, and is relatively inexpensive to build.

    The circuit diagram from the original paper is shown above. It uses two op-amps for amplification and filtering, and was designed to be powered by two 9V batteries. I will use the same circuit, but plan to use a 9V DC power supply for simplicity.

    Most of the components arrived from Mouser Electronics today, and I can get started once a few more things (like the circuit boards) arrive. I plan to build one single channel amplifier to work out the process (little box on top), then assemble a four channel unit to record multiple beetles at once (bottom box).

    The middle box will house the analog-to-digital converter (ADC), which will allow me to record the data on a computer.

    I will post more details about the setup and procedures as things progress.

    Special thanks to Dr. Hans Ruppel, whose support is making this project possible.

  • One Project Becomes Two

    After working very hard this winter to submit a manuscript describing the most recent results of the project, I realized that it has really become two non-overlapping lines of inquiry.

    A few weeks ago, I submitted a manuscript titled “Batesian Mimicry and Thermal Resilience Among Tenebrionid Beetles from a New Mexican Piñon-Juniper Savanna” to the Journal of Experimental Biology. The editor said some kind words about it, but ultimately rejected it because it did not fit comfortably into the aims of the journal. The main complaint was that a significant portion of the paper focused on the ecology of the beetles, rather than their physiology.

    It took a few days for me to realize that the paper had evolved into something different. Looking over the title, two things may stand out.

    Batesian Mimicry

    Thermal Resilience

    Those are really two separate concepts and analyzing either one can be performed relatively independently of the other. In other words, this was two incomplete papers rather than one solid story.

    Now begins the process of completing both of those stories.

    Mimicry

    Several lines of evidence address whether the Asidini Philolithus elatus and Stenomorpha rimata are Batesian mimics of the Amphidorine Eleodes obscura. For an organism to be a bona fide Batesian mimic it must

    • Resemble the model in the eyes (or ears or nose) of potential predators.
    • Be palatable
    • Be undefended (or at least to a potential predator)
    • Overlap the model in space and/or time so that predators can learn the association
    • Be relatively uncommon to prevent predators from discovering their mimicry

    The Asidini fulfill these criteria to varying degrees

    • The major argument for mimicry is that the Asidini look a lot like E. obscura, and are about the same size and mass.
    • A close relative of S. rimata, S. marginata, has been shown to be palatable to mice and skunks. Palatability of P. elatus is unknown.

    On the minus side:

    • P. elatus will regurgitate when handled, suggesting at least mild defense
    • Headstanding behavior, which contributes to the mimicry, is weak (P. elatus) or non-existent (S. rimata)
    • Both Asidini are at least as common as E. obscura during peak season, giving predators plenty of opportunity to learn that they are quite edible.
    • Stenomorpha rimata is present in late September and October, when Eleodes have disappeared from the surface, giving predators plenty of time to learn that they are tasty and undefended.

    I really need to know who the local predators are, so that I can make sense of all this. I hope to use the upcoming field season to find out who is eating beetles around here. Based on scats and scattered body parts, someone is eating them, but who?

    Thermal Resilience

    Maintenance of scent glands is costly, so E. obscura should either use more metabolic energy than the undefended P. elatus and S. rimata, or devote less energy to other aspects of fitness. Based on respirometry across a range of temperatures it would appear that all three species use the same amount of energy per unit time, but the Asidini have much higher survival at elevated temperatures.

    This is a nice partial story, but I need to know more about possible mechanisms. Two sets of experiments would be very helpful in completing this part of the story.

    • Testing survival across a full range of temperatures. I have only tested up to 40C, which is semi-lethal to Eleodes but does not strongly affect P. elatus or S. rimata. Although I am no fond of the idea, I need to test up to a temperature that is 100% lethal in order to have a complete picture of thermal resilience.
    • Because temperature induced lethality is associated with disrupted ionic regulation, it will be important to examine concentrations of ions in the hemolymph (blood) of E. obscura, P. elatus and S. rimata at high temperatures.

    If all goes well, I should have two papers ready by the end of the season. Wish me luck.

  • Owlet Posts Reorganized

    Screech owl fledgling on Terry’s patio.

    Because it took so long to load when they were all on the same page, I have moved the owlet videos to new a series of pages. It’s slightly more hassle if you want to see all of them at one sitting, but it beats waiting what seems like forever for the pages to load. If you love it or hate it, use the contact link to send feedback.

  • The Game’s Afoot!

    Or underfoot, as may be.

    Philolithus elatus have started to emerge

    Last fall, we gathered data on the physiology, temperature sensitivity and lifespans of Eleodes obscura and its presumed mimic Philolithus elatus. The data were interesting and I have drafted a paper, but it seemed worth trying to replicate the results to be sure the data were solid.

    One of the limitations of working with a seasonal organism, like P. elatus, is that one can only work during a narrow window, when the animals are available and alive. True stink beetles, like E. obscura, survive for years, so one can simply collect a bunch and then do experiments almost indefinitely. Philolithus die less than two months after emerging, then are completely gone until late the next summer.

    Hence my excitement at finding the first P. elatus of the season.

    The first Philolithus elatus collected in 2025. 7/27/25.

    More are emerging every day. We now have seven P. elatus available for experiments, and are hoping to bring the total to twenty within the next week. There are plenty of E. obscura available as well. We should soon have a big pile of data to add to the manuscript.

    For a little more info on P. elatus, check out the new Wikipedia page that I started.

  • Owl Cam: Maybe a Week To Go

    The owlets in the nest box have been growing at an astounding rate, and are well on their way to fledging. The parents have been delivering food constantly, and the chicks get more active and inquisitive all the time.

    Sleepy parent having a look out the doorway. Credit Terry Morgan, 5/10/25.

    The parents have been out and about quite a bit, and seem unbothered by the presence of observers and paparazzi.

    Parent, probably mom, resting in the late morning. 5/14/25.

    Family Album from Past Years

    This seems like a good time to reminisce about past broods. It’s hard to know how long these particular parents have been rearing young in Terry’s box, but screech owls have been nesting there for many years. Terry has many more excellent photos; here is a small sampling.

    Parent resting on a chair on the patio. Credit: Terry Morgan.
    Four fledglings and a parent (far right) in the eaves. Credit: Terry Morgan.
    Fledgling on the patio. Credit: Terry Morgan.
    Fledgling in a pinyon tree. Credit: Terry Morgan.

    The drama in the nest box continues. Based on past broods, he expects them to fledge on or about May 22. As always, stay tuned for more.

  • Owlets Have Hatched!

    As Terry predicted, the eggs started to hatch last night. So far three of the eggs have hatched, which is a local record for simultaneous emergence. This may be the result of the female owl having left the first eggs on their own during the early days.

    Three owlets sprawled on their siblings’ eggs. 4/22/25.

    At the moment, the owlets look like fuzzy blobs, but in the video you can see three sets of wiggly heads, bodies, and wings.

    Let’s hope for the other two to hatch successfully in the next few days.

  • New Feature: Species Pages

    In addition to its other functions, this site serves as a notebook for keeping track of data and references. In our effort to keep a handle on the local species’ characteristics and publications, information about each will be posted on its own page.

    Eleodes obscura, participating in notetaking. 9/20/23.

    The first species to receive this honor is the prominent, large, and widespread stink beetle, Eleodes obscura. It has been the subject of field surveys, respirometry experiments, and longevity studies here at the lab, and may be the most studied species of Eleodes.

    Expect more pages to become active with time. Hopefully, this will become a resource that many people in the community can make use of.

  • Owls Settling Down

    Terry’s owls are getting serious about the business of parenting. The female appears to have decided that five eggs are enough, and is incubating them full time. The male has been bringing her mice, and she has been dining in rather than leaving the box to eat them.

    Owls in the box. The male (right) has brought a mouse to feed the female while she incubates the eggs. The mouse is in her mouth at the bottom center of the image. 4/2/25.

    Five eggs will be a pretty good brood if they all hatch and survive. For the next few weeks, she will be tending them, with the first egg expected to hatch about April 22.

  • New Feature: Owl Cam

    New Season of an Ongoing Project

    For several years, our neighbor Terry has been recording and posting footage from his camera inside a next box occupied by a pair of western screech owls. He has always had a strong following on Facebook, but for those of us who do not use the platform, he has offered to make the information and videos available here on the Lab web site.

    Black and white image of an owl sitting inside a nest box
    Owl resting triumphantly after removing the mirror that had been mounted on the upper right. 3/4/25.

    Once again, they have prepped the nest box and have started to lay eggs. The first video clips have been uploaded to Terry’s Owl Cam page, along with his comments and a spreadsheet of data regarding previous broods.

    New videos and commentary will be uploaded regularly, so stay tuned for plenty of drama and excitement. There are two eggs now, with more to come, and then it will be about another month before they hatch. Once the eggs hatch, there will be a festival of cuteness as the little fuzzballs eat and grow for roughly another month before they fledge.

  • Setting Up Pitfall Traps for Beetle Surveys in 2025

    Starting surveys for 2025

    Photo of grassland with a small cholla cactus in the center foreground, small juniper and pinyon on the right side, and larger junipers in the background. Small blue flags are located at regular intervals.
    Trap location, looking northeast. Small blue flags remain in place to mark locations of traps. One trap, with a painted cover held down by a rock, can be seen in front of the cholla cactus. 3/3/25.

    Inspired by comments from my friend and colleague Dr. Drew Talley, and conversations with a local Master Gardener, we set up a small array of pitfall traps to collect and record beetles over the course of the year.

    It is a 3 X 3 grid, so nine traps total, spaced 3 meters apart. We set out flags to mark the locations of the traps in a section of the back acre of the lab where foot traffic was minimal.

    Blue plastic cup buried in red sand surrounded by grasses.
    Pitfall trap, consisting of a plastic cup buried to the rim . Note that the rim is flush with the soil. 3/4/25.

    The traps are plastic party cups, buried to the rim. The soil is quite loose, so placing the traps was easy.

    Painted wooden square, with legs partially buried in soil. Rock on top.
    Pitfall trap with plywood cover. Legs are partially buried, leaving space for entry of beetles. 3/4/25

    Once the traps were in place, we put plywood covers over them to keep debris out and shield any animals that fall in.

    Plywood covers with wooden legs, unpainted.
    Plywood covers for pitfall traps before painting. Covers are 6 X 6 pieces of plywood with 3/4 wooden dowels screwed into place.

    The covers are 6″ X 6″ pieces of plywood, each with three legs made from 3/4″ dowels. The 3″ legs allow them to be partially buried for stability. Once screwed together they were given a few coats of latex paint to protect them from the elements.

    We’ll set traps for the first week of each month, for five nights at a time.

    I have not seen beetles in the neighborhood before April, so it is unlikely any will fall into the traps this month. Knowing when beetles are not active provides an important baseline for when they first appear.