Arachnews: February 24, 2020
Your weekly roundup of news and science about spiders, scorpions, and more.
Published in
16 min readFeb 26, 2020
In this week’s roundup: several research positions available; new Zefrank; lots of ecology papers; house spider evo-devo; and new species from around the world.
Note: Terms in bold are defined in the Glossary at the end of the post.
Art & Social Media
Threads
Education & Outreach
- NEW. ZEFRANK. PEACOCK. SPIDERS. [YouTube] (Curious about why the female was also posing like she was about to dance at the end of the video? We were too! Turns out, this is a rejection signal — females pose this way to tell the guys to buzz off.)
- “As I watched this spider make its way across the top of the glistening January snow, I had to consider a new possibility: could spiders, with their soft bodies and fragile-looking legs, really be able to brave winter’s chill and boldly walk about on the snow?” Susan Spikol encounters winter-active spiders in New Hampshire. [Northern Woodlands]
Events & News
Research
- Michael Henshaw at Grand Valley State University, Michigan is looking for a Masters student to study genetic differences between populations of the bold jumping spider (Phidippus audax). “A tuition waiver and a stipend ($4000 per semester) are secured for the first year, and can potentially be extended for a second year pending good progress. Additional support for the project is available within the institution.” [✉️ Michael Henshaw]
- The Hillier Lab at Acadia University, Nova Scotia is hiring for several research positions, including a MSc in Varroa mite chemical ecology. The start date is May 2020 or sooner; apply as soon as possible. [Twitter]
- Aleksandra Mieczkowska of the University of Białystok, Poland, who is studying hymenopteran parasitoids of spiders, is looking for parasitized spiders from around the world, as well as information on rearing the parasitoids from imagos. [✉️ Aleksandra Mieczkowska]
Conferences & Events
- The Staffordshire Invertebrate Science Fair is on March 7 at Staffordshire University, Stoke-on-Trent. The British Arachnological Society and Meg Skinner will be representing arachnids. [Twitter] [Facebook]
- The Gordon Research Seminar and Conference on Venom Evolution, Function and Biomedical Applications will be held this August in Vermont. Applications for financial aid and to give talks are due May 8. [GRS] [GRC]
- The 32nd European Congress of Arachnology is coming up this August in Greifswald, Germany. Grant applications are due April 1; early bird registration closes May 1, and the deadline for abstracts is June 1. [Twitter]
#PruittData
- The podcast Big Biology interviews American Naturalist editor Daniel Bolnick on the unfolding revelations of unreliable data collected by Jonathan Pruitt, a prolific behavioural ecologist who specializes in social spiders. A good introduction to the whole thing. [Big Biology]
- Related: Jeremy Fox puts the ongoing broader conversations about scientific misconduct and retractions in historical context. How widespread is fraud or data manipulation? How common are retractions? Who tends to commit fraud, and why? [Dynamic Ecology]
Research
Ticks and Tick-Borne Disease
- Australia’s weird animals have equally weird ticks that we know amazingly little about. The authors say this is the first study of the bacteria carried by native Australian ticks, which is wild. They looked for bacteria known to cause disease in humans in other parts of the world, like Borrelia burgdorferi; they only found Rickettsia, which they already knew about. They did find some bacteria that are probably new to science. [Paper] [Sci‑Hub]
- The cattle tick Rhipicephalus microplus can carry Rickettsia bacteria that cause diseases like spotted fever. Researchers in Brazil analyzed a handful of ticks from various regions to see which species of Rickettsia they were infected with. It’s possible that ticks can become infected with new species by feeding on the same animal as an infected tick! [Paper] [Sci‑Hub]
- Ticks can survive harsh conditions by entering a dormant state called diapause, kind of like hibernation. Researchers compared active, summer-diapause, and overwintering Dermacentor silvarum ticks to see how many genes were switched on and off in each phase, and what those genes might do. [Paper]
Agriculture
- The mite Aceria litchii, which damages the leaves and flowers of lychee trees, is one reason Brazil’s lychee industry hasn’t been doing so hot lately. Researchers compared five varieties of lychees to see which are naturally better at resisting the mite. Best: Americana. Worst: Bengal. [Paper] [Sci‑Hub]
- As regular readers will know, various species of predatory mites are used as biological pest control for the two-spotted spider mite (Tetranychus urticae). Two common commercially available species are Phytoseiulus macropilis and Neioseiulus californicus. What happens if you use both together? Are they competing for the same food source? Will they eat each other? Find out in this paper. [Paper 🔓️]
- Amblyseius chiapensis, a mite found in the forests of Brazil, is really good at eating two-spotted spider mites—better than commercially available species—and could maybe be used as pest control. [Paper] [Sci‑Hub]
- Bt rice is a kind of genetically engineered rice that has a gene from the bacteria Bacillus thuringiensis (hence the name) that creates built-in pesticide. While it was first developed in China and was approved for production over 10 years ago, as far as I can tell it is not actually grown as a crop in China—just sold elsewhere. There is a large body of research devoted to demonstrating the safety of Bt rice, and this recent paper is the latest addition. It looks at whether Bt rice affects spiders, which are important predators of planthoppers. [Paper 🔓️]
Technology
- As we explained a couple weeks ago, one obstacle in studying certain peptides and proteins is that they like to clump up. Spider silk is made out of these molecules, and spiders are very good at keeping silk in liquid form inside their bodies. How do they do it? Spider silk proteins (spidroins) have special bits on the ends (or, in scientific terminology, N-terminal domains) that keep them from linking up. A recent thesis (memorably titled “A star is born” and based in part on that earlier paper) examines how spidroin NT works and designs a mutant version (NT*) that can be used in the lab. [Paper 🔓️]
- Spider silk is medically useful because it can safely be used inside the human body—it’s not toxic and it doesn’t make your immune system freak out. A group of researchers in Sweden have used spider silk to make antibacterial coatings for surgical implants. [Paper 🔓️]
- Want to know more about spider silk in medicine? Here’s a review of how various researchers have used spider silk in tissue engineering. It’s been used as scaffolding for regrowing nerves; meshes and foams to grow cells in; wound dressings; and more. [Paper 🔓️]
- Here’s a robot inspired by the wheel spider! Like the spider, it moves faster when rolling than walking and can go from walking to rolling and vice versa. [Paper]
- And here’s a design for a robot based on a jumping spider. [Paper]
Ecology
- At Los Tuxtlas field station in Veracruz, Mexico, three species of Centruroides scorpions coexist by carving out their own niches. C. gracilis lives in pasture and young secondary forest. C. flavopictus lives in primary forest, but can also be found in secondary forest; it avoids the larger C. gracilis by staying in trees. And C. rileyi lives on trees in primary forest, probably to avoid the larger C. flavopictus. [Paper] [Sci‑Hub]
- Over the past two hundred years or so, European settlers wiped out nearly all of North America’s prairies for agriculture. There are now many projects aiming to restore this habitat, but they mostly focus on plants. How effective are they at restoring prairie spiders? A study of Ohio State University’s patch of reconstructed prairie compares its spiders to those found in prairie remnants and old farm fields. [Paper 🔓️]
- Spiders are well-known for sexual cannibalism, but they are also prone to just plain old cannibalism. In the South American wolf spider Lycosa poliostoma, adult females are more likely to eat others when they’re hungry or when the other spider is infringing on their turf. [Paper]
- Researchers in southwest Ohio noticed that over a few years, Pholcus manueli cellar spiders displaced the larger and longer-established species P. phalangioides. To figure out how, they staged a spider fight club. Their conclusion: P. manueli knows when to hold ’em, knows when to fold ’em, knows when to walk away, knows when to run. [Paper] [Sci‑Hub]
- Roses are red,
Tarantulas are good pets,
Spiders are the main arthropods
found preying on vertebrates. [Paper 🔓️] - DNA barcoding has made it possible for scientists to analyze the genetic diversity of whole communities of spiders, identify what a spider has been eating without actually having to observe it, and more. But it still has many limitations. Here’s an overview of how DNA barcoding works—and doesn’t—in regard to spiders. [Paper 🔓️]
- The UK has a long tradition of amateur naturalists, as well as scientists, recording where they’ve seen various species. This has given us decades of fine-grained data about where species occur. Researchers analyzed this data to look at long-term trends for various groups of invertebrates, including spiders. The big picture is surprisingly complex, “[challenging] the received wisdom that all biodiversity change is loss, and that it is both pervasive and unalterable.” The results come with lots of caveats—this doesn’t directly measure other aspects of biodiversity, and while the data starts in 1970, biodiversity declines must go back to the Industrial Revolution. [Paper] [Sci‑Hub]
- How do colonies of social spiders choose where to live? Experiments with the social spider Stegodyphus dumicola tested which structures (closed vs. open) individual spiders preferred, and what happened when the colony collectively had to decide. While groups sometimes fragmented, the smaller group always joined the majority—a model the authors call “democratic decision-making”. 1) press X to doubt; 2) insert Democratic primary jokes here. [Paper] [Sci‑Hub]
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Note: Pruitt is an author on this paper, but the last author has confirmed the data isn’t from the Pruitt lab.
- “[The] human/toad relationship throughout western history has always been very conflicted,” observe the authors of this paper. In Brazil, toads are seen as ugly, gross pests, and people try to keep them away from their houses. But the widespread yellow cururu toad (Rhinella icterica) is really good at eating the medically significant scorpion Tityus serrulatus. To clarify: the scorpion is medically significant to humans. The toads seem to be completely immune! Isn’t that amazing? Rehabilitating toads’ reputation (and habitat) could be key in controlling populations of T. serrulatus, which are increasingly a public health concern. [Paper] [Sci‑Hub]
- Cities can be harsh places for most invertebrates. Impervious surfaces like concrete make for poor habitat (and contribute to higher temperatures), and green space occurs in isolated patches. This study on the arthropods of Turin, Italy finds that spiders and mites are especially affected by urbanization. [Paper 🔓️]
- Here’s your regular instalment of Weird Cave Animals! The quartzite caves of Minas Gerais, Brazil are home to an unusually rich variety of animals, particularly spiders and harvestpeople. A few are strictly cave-dwellers, while others live on the threshold. However, tourism and deforestation are both impacting life in the caves. [Paper 🔓️]
- Tiny oribatid mites in rocky habitats have stronger claws than those that live on soft ground, an adaptation that can also be found in many birds and reptiles (but is up for debate). [Paper 🔓️]
Evo-Devo
The journal Development Genes and Evolution just published a bunch of articles about how genes control development in spiders! Mostly in the American house spider (Parasteatoda tepidariorum), the zebrafish of spiders.
- The transcription factor FoxB is a protein that attaches to DNA and acts as a “switch” that turns certain genes on or off. Previous experiments (which we wrote about last November; ctrl+F “FoxB”) showed that FoxB turns off dorsal (top-side) genes and turns on ventral (bottom-side) genes. When they deactivated the gene that makes FoxB, it messed up spider embryos in an interesting way. Their legs were, like…all the top of the leg. No bottom of the leg. (See Fig. 1.) Anyway, the same researchers have discovered two more disturbing but interesting ways repressing FoxB messes up spider embryos. The results are consistent with FoxB playing a role in making the top side of a spider different from the bottom side of a spider. [Paper 🔓️]
- How come spiders have pedipalps (the short, leg-like appendages* on either side of their fangs) and insects don’t? In both groups, that particular body segment is controlled by the same gene, lab. Researchers combed through the genome of Drosophila melanogaster to make a list of all the genes that might interact with lab, and looked for their equivalents in P. tepidariorum. Then they checked to see if any of those genes were expressed differently in pedipalps vs. walking legs. The results were dismal (3 out of 75), perhaps indicating that comparing fruit flies and spiders is like comparing apples and oranges. [Paper 🔓️]
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* Something I’ve come to learn about spider development—arthropods in general, really—is that basically everything is a modified appendage. Spinnerets? Modified appendages. Chelicerae? Modified appendages. Book lungs? Believe it or not, modified appendages. Evolution likes to build on what you already had, and when your ancestor had many repeating sets of legs, well…
- We know surprisingly little about how spiders sense the world! You can probably guess that whisker-like setae (hairs) on their legs sense airflow and vibrations, but did you know some of them are used to smell or taste? Here’s a study that looks at how and where P. tepidariorum’s sense organs develop as it grows, with special attention to those chemosensory setae. [Paper 🔓️]
- How does one tell the difference between male and female spiders? The many forms sexual dimorphism takes in spiders—different genitalia, body sizes, behaviour, life history—are common knowledge among arachnophiles, but opaque to outsiders. This article is a good, conventional overview of sexual dimorphism in spiders, how sex differences arise in spider genomes, and what they might tell us about sex among animals in general. [Paper 🔓️]
Miscellaneous
- Well-preserved horseshoe crab fossils from a quarry in central Poland may have died from an algal bloom. [Paper, in Polish 🔓️]
- Here’s a very cool-looking PhD thesis on Demodex face mites! As we’ve mentioned previously (ctrl+F “Demodex”), we still don’t know much about these critters. This thesis promises to cover many topics, like possible ways to rear them in a lab; how to identify them under a microscope and with DNA sequencing; and what factors affect how many face mites a person has. It is embargoed, but will hopefully be published in some form soon. [Paper]
- Another embargoed PhD thesis that is just too cool not to write about: using mites for forensic analysis! This involved leaving dead pigs in the woods and comparing them with “mites collected from three crime cases”. There’s a heck of a story here. [Paper]
- This Masters thesis analyzes RNA from five common spider species to compare the genes expressed in their silk glands to those in the rest of their body, and then comparing those genes across species. They are similar, maybe because they were all inherited from a common ancestor — but more samples are needed to figure it out. [Paper 🔓️]
Taxonomy
- Reconstructing evolutionary history from over half a billion years ago is a bit like trying to hear words through heavy static. There’s a lot of “noise”, many parts of the message are lost, and different people will interpret the same sounds in different ways. A group of researchers re-analyzed a big dataset of arthropod genetics from 2010. Their interpretation places horseshoe crabs among arachnids—which would mean that the aquatic ancestors of arachnids came onto land, and then some returned to the water. And maybe some came back a second time. It’s a wild read. [Paper 🔓️]
- There are over 200 species in the erythraeid mite genus Leptus, found around the world. You’ve probably seen them as larvae, parasitic on insects, spiders, and other arthropods. And now there’s an updated identification guide to all of them. [Paper] [Sci‑Hub]
- A new e-book from Joerg Wunderlich collects five recent papers on spiders, both fossilized and live, from around the world. [Paper 🔓️]
Americas
- A Masters thesis proposes a new “family tree” for the small wandering spider family Xenoctenidae. (Hold your horses. According to ICZN rules, it’s not official yet; it has to be published elsewhere.) [Paper, in Portuguese 🔓️]
- A new ray spider, Cuacuba ribeira, from caves in southern Brazil. [Paper] [Sci‑Hub]
- Three new Euathlus tarantulas described from Argentina. [Paper] [Sci‑Hub]
Africa
- Two new buthid scorpions from Morocco and Egypt, and also a redescription of a closely related species from the Middle East. [Paper 🔓️]
Asia
- Four new Qiongthela liphistiid spiders from Hainan Island, China. These spiders are from an ancient lineage that split off from the ancestor of all spiders and has changed very little since. [Paper 🔓️]
- A female Pristidia cervicornuta sac spider was found for the first time, also on Hainan Island. [Paper 🔓️]
- A new oribatid mite, Dicondyla fossalis, found in leaf litter in Yunnan, China. [Paper]
- Three new Belisana cellar spiders from Yunnan, China. [Paper]
- A new species of oribatid mite not found in leaf litter for once. It’s from the canopy of a Borneo rainforest! Several other species were also found there, the first time they have been found in Borneo. [Paper]
- A whopping 31 new species of psilodercid spiders in the genus Leclercera have been described from specimens collected across southeast Asia. [Paper 🔓️]
My apologies for the lateness! As always, thanks to everyone for reading, and to Sebastian Alejandro Echeverri for editing. Suggestions and corrections are always welcome; just drop us a (silk) line at @arachnofiles.
Glossary
- diapause: a dormant state, kind of like hibernation. Arthropods can enter diapause seasonally, in response to environmental conditions, or as part of their life cycle.
- DNA barcoding: identifying an organism by comparing a short, distinctive bit of its DNA to a reference library of samples from many species. There are very few spider barcodes.
- dorsal: the “back” side. In animals like insects and spiders, it’s their top side. See ventral.
- impervious surface: ground that water can’t soak into, i. e. pavement, asphalt, and so on. Ubiquitous in urban areas, impervious surfaces are hostile habitats for tiny creatures, raise the temperature of the surrounding area, and increase the amount of rainwater or melted snow that flows into city sewers. Cities have several ways to address this, like restricting parking pads, mandating green roofs, and implementing a stormwater charg—no no no, get a grip, Neville—
- N-terminal domains: the end of an amino acid/peptide/protein with a nitrogen (+3 hydrogens). On the other end, there is the C-terminus: a carbon (+2 oxygens). Kind of like the studs and sockets on LEGO, amino acids attach to each other by the N-terminus of one molecule bonding to the C-terminus of another.
- pedipalps: the non-walking appendages that flank an arachnid’s mouthparts. In spiders, they are like legs but much shorter, and in males, modified to transfer sperm during mating. In scorpions and pseudoscorpions, they’re pincers. In amblypygids and vinegaroons, they’re grabby claws. And so on.
- peptides: the “building blocks” of proteins. Peptides themselves are made built out of a type of molecule called amino acids. A peptide is made up of a few amino acids stuck together in a row, and a protein is made of a lot of peptides stuck together in a row.
- primary forest: older forest that hasn’t been clear-cut.
- secondary forest: younger forest that grows on land that was once cleared by logging or farming.
- setae: the spikes or hairs on spiders’ legs. They often have the ability to sense things, like vibration or smells. The singular form is seta.
- spidroin: spider silk protein. It is liquid inside a spider’s body, and turns into tough fibers as it is expressed by the spinnerets.
- transcription factor: a type of protein that gloms onto DNA and affects how often genes are expressed. Because there are so many different kinds of transcription factors, their effects can be varied: some turn genes on and off, others only do so in specific parts of the body or at specific times in development. Changes in how genes are expressed, as done by transcription factors and other systems, are a big reason that we can share most of our DNA with other animals and yet look so different. For an audio/visual example, see A Capella Science.
- ventral: the “belly” side. In animals like insects and spiders, it’s their bottom side.
