Arachnews: March 9, 2020
Your weekly roundup of arachnid art, news, and science.
Published in
15 min readMar 10, 2020
New issues of Systematic and Applied Acarology, Experimental and Applied Acarology, and Acarologia means lots and lots of mite papers this week. There’s also nematodes, hair- and/or eyebrow-raising medical case studies, pretty spider photos, and more.
Words in bold are defined at the glossary at the end of the post.
Art & Social Media
- An amazing sight from Chile: baby tarantulas, marching in single file. In @Arachno_Cosas’ thread, a few arachnologists weigh in; their consensus is that the spiderlings do this as a defense while dispersing. [Twitter]
- Mo Kaze and Maureen Berg have been pondering whether face mites eat makeup. Kaze’s trial run turns up one leggy face boi! [Twitter]
Education & Outreach
- Kevin Wiener, of All Bugs Go 2 Kevin, puts his bare hand into a bin of brown recluses to show how non-aggressive they are. Even when poked and cornered, they don’t defend themselves—they just run away! This is a great demonstration of why the brown recluse’s reputation is far overblown. However, we don’t recommend trying this at home; it is far too easy to accidentally kill spiders when handling them directly. [Twitter]
- A recent episode of Australian kids’ TV show Totally Wild features the Queensland Museum’s spider exhibition! (I saw an earlier iteration of this exhibit when it was at Toronto’s Royal Ontario Museum; interesting to see bits of how it’s adapted for different countries.) Segment is from about 4:50–13:05; it’s geo-locked content, but I hear there’s ways around that. [Channel Ten]
- Australian Geographic covers Bruno Buzatto and Braxton Jones’ ongoing funnel web spider research, including the funnel-web that got eaten by a gecko, tracking device and all. [Australian Geographic]
- It’s time for the annual animal kingdom smackdown: March Mammal Madness! As in previous years, it’s not strictly limited to mammals; this year there is an arachnid contestant, the face mite Demodex, going up against the Australian feral camel. For updates and play-by-plays, follow the official Twitter account. [Mammals Suck]
Events & News
- Spider venom researcher Samantha Nixon will be speaking at Science Unplugged at World Science Festival Brisbane, alongside volcanologist Heather Handley and ornithologist Gisela Kaplan. Saturday, March 28, 10:30 AM, State Library of Queensland. [World Science Festival]
- The latest issue of Acarologia features an obituary for British acarologist Donald Macfarlane, who passed away this past September. He had a long career identifying mites at the Institute of Terrestrial Ecology and other government agencies and teaching courses in the UK and abroad; a genus of mites (Macfarlaniella) and 13 new species were named after him. [Acarologia]
Research
Health & Medicine
- This paper about the endosymbionts in ticks and fleas on opossums (Didelphis aurita) in Brazil doesn’t even have any pictures of tick- and flea-infested opossums. Here’s the sketchiest-looking Creative Commons-licensed picture of an opossum I could find. I’ve been spoiled by the disgusting bounties of PLoS: Neglected Tropical Diseases. Anyway, after searching nearly 60 opossums they found only one Amblyomma sculptum tick nymph, which is hopeful news. Opossums are the reservoir—“natural habitat”, so to speak—of the bacterial endosymbiont Rickettsia rickettsii. But A. sculptum ticks that feed on the opossums can get infected and pass it on to humans, where it causes spotted fever. [Paper] [Sci‑Hub]
- The bacteria Borrelia burgdorferi hangs out in mice most of the time. When ticks feed on mice, they get Borrelia. Then the ticks feed on humans and humans get Borrelia, which makes them sick.
T̶h̶e̶n̶ ̶v̶a̶m̶p̶i̶r̶e̶s̶ ̶f̶e̶e̶d̶ ̶o̶n̶ ̶h̶u̶m̶a̶n̶s̶ ̶a̶If you target the reservoir population—mice—you stop Borrelia from ever getting to humans. In a recent study carried out in Connecticut, researchers left vaccine-coated food pellets in bait boxes for mice. Two years later, Borrelia infections in ticks had dropped dramatically. It’s worth reading the whole paper for more details on how the study worked. [Paper] [Sci‑Hub] - Here’s a case study of a lady in Bogotá who may have been bitten by a false widow spider (Steatoda). They’re not sure what it was because “immediately after being bit, the patient hit the spider with the back of her hand and it fell to the ground, where her dog swallowed it. The dog presented with vomiting and general discomfort after ingestion.” Both of them are fine now. [Paper 🔓️]
- A new book, Case Studies In Emergency Medicine, collects cases “not so rare as to reach the status of ‘Zebra’ but at the same time were not bread-and-butter emergency medicine presentations.” One of those is the case of a seven-year-old boy who fell out of a tree and apparently landed near the web of a black widow, who bit him, causing muscle cramps and spasms (a classic symptom of latrodectism). The child was treated with antivenin and recovered after a few days. Also: “After the patient’s family was informed about the possible spider bite, the parents went to the site of the fall and found a tattered, irregular-shaped web with what appeared to be an egg sac suspended from the web. Dad doused the small woodpile with gasoline, tossed a match into it, and, in a bit of ironic karma, suffered minor flash burns when the gasoline vapor ignited explosively. The spider and her young did not survive.” [Paper] [Sci‑Hub]
- A doctor who says he has been bitten several times by brown recluses writes that he successfully treated the lesions with trichloroacetic acid (TCA). This chemical is often used in facial peels (it’s a bit stronger than the do-it-yourself stuff) and as wart remover because, well, it makes your skin peel. He notes that it is also used in labs to denature protein like DNA, and perhaps that is why it works for the protein-based toxins in spider venom. I have a lot of questions, like what the heck he’s doing to get bitten by brown recluses so often, whether he’s actually found them at the site of the bite, and if it’s common for doctors to try random stuff on themselves just on a whim. (Editor’s Note: History says yes.)[Paper 🔓️]
- The Dermatological Manual of Outdoor Hazards includes chapters on spiders and scorpions, mites, and ticks. The authors make a point to say that while there are many cases of people saying that a spider bit them, but “there is usually a more likely explanation”: usually a skin infection. The authors cover the symptoms of confirmed bites from various spiders (and stings from various scorpions). Even in the case of the brown recluse, “bites are almost-never life threatening.” [Paper] [Sci‑Hub]
Food & Agriculture
- Chicken mites (Dermanyssus gallinae) are common parasites of hens raised for eggs. However, pesticides can harm the chickens and also may not even reach the mites, which can hide in tiny cracks and crevices. A possible solution: Beauveria bassiana, a fungus that infects and kills mites. Researchers in Brazil made traps out of corrugated cardboard and loofah sponges coated with Beauveria spores. The results are promising! [Paper] [Sci‑Hub]
- You know how food packaging always says “store in a cool dry place”? Do it! Among other things, it cuts down on contamination by the potentially allergy-causing mold mite Tyrophagus putrescentiae. [Paper] [Sci‑Hub]
- The rice panicle mite (Steneotarsonemous spinki) is a major rice pest in Asia, the Caribbean, and Central America. Could it spread to other rice-producing regions? This paper uses data about climate and the rice panicle mite’s current range to predict which areas have conditions favourable to S. spinki. [Paper] [Sci‑Hub]
- Related: the same kind of thing, but for the lone star tick (Amblyomma americanum) in New Zealand. The Asian longhorned tick (Haemaphysalis longicornis), which has been established in New Zealand for a long time, has recently spread to the United States. It is doing just fine in the lone star tick’s native range, which raises the question of whether the lone star tick could live equally well in New Zealand. [Paper 🔓️]
- Varroa destructor isn’t the only bee mite that’s a threat to honeybees; it’s merely the most notorious. In Papua New Guinea, the invasive Varroa jacobsoni and Tropilaelaps mercedesae have also taken a toll on the industry. The two species require different methods: the pesticide Bayvarol works better on V. jacobsoni, and “queen caging” or “queen removal”—confining or removing the queen bee to temporarily stop her laying eggs—is more effective for T. mercedesae, which can only feed on young bees. [Paper] [Sci‑Hub]
- Two-spotted spider mites (Tetranychus urticae), a widespread agricultural pest, are becoming resistant to commercial acaricides, and it’s a Problem. It’s easy to say “use less pesticides,” but it’s hard to find new compounds that kill spider mites while sparing the predatory mites that are also used to manage them. A combo that worked well in this study: essential oils from white paperbark (Melaleuca leucadendra) and Brazilian peppertree (Schinus terebinthifolia). [Paper] [Sci‑Hub]
- Another strategy to fight two-spotted spider mites is to find native species that prey on them. In Brazil, one candidate is the predatory mite Amblyseius chiapensis, found on the leaves of (vulnerable!) Trichilia casaretti trees. Previous research showed A. chiapensis could eat two-spotted spider mites. But can they thrive eating only two-spotted spider mites, and are they better at it than commercially available species like the widely used Neoseiulus californicus? [Paper] [Sci‑Hub]
- Plants aren’t just passive organisms — they can actively defend themselves against animals eating them. (And yes, they can “tell” the difference between being eaten and just, like, being stepped on.) Based on certain conditions, plants start making hormone signals (yes, just like your own body) that activate different kinds of defenses. For example, plants release jasmonic acid as a signal (to both other parts of the same plant and other, nearby, plants) to start making toxic chemical compounds. And salicylic acid is a signal to emit chemicals that attract the predators of plant-eating animals. (Interestingly, these two pathways seem to work against each other: turning one up turns the other one down.) For a closer look at how these processes work, researchers analyzed what genes got turned on or off in two kinds of pepper plants (Capsicum) infested with two-spotted spider mites (our old friend T. urticae). [Paper 🔓️]
- Who’s eating aphids in organic apple orchards? A study of spider populations in several orchards in southeast France found lots of yellow sac spiders (Cheiracanthium mildei) in the branches, and mostly ground spiders (Drassodes) and jumping spiders (Pseudoeuophrys and Icius) at ground level. [Paper] [Sci‑Hub]
Ecology
- Are spiders in grasslands like wolves in Yellowstone, who allow vegetation to flourish by limiting the population of deer? Or are they more like big fish in the ocean, whose fate ultimately depends on the masses of tiny plankton at the base of the food chain? The first kind of view is “top-down”; the second is “bottom-up”. To test several different hypotheses put forward over the years, researchers measured plant, insect, and spider biomass from 54(!) sites in grasslands across North America. Perhaps unsurprisingly, considering that spiders are both predators and prey for other animals,there are both top-down and bottom-up explanations for what they discovered. [Paper] [Sci‑Hub]
- These researchers tried to breed two-spotted spider mites that preferred tomato to cucumber and, to their surprise, it didn’t work. Do they have some built-in preference for cucumber that persists even when only mites that pick tomato move on to the next generation? Is this an ecological trap? [Paper 🔓️]
Endosymbionts
Lots of arthropods, including arachnids, have bacteria living inside their cells. These are called endosymbionts. Here’s a couple recent cool papers about them.
- So one of the coolest things parasites, including some endosymbionts, do is reproductive manipulation: they alter their host’s sex or fertility to their own advantage. A few bacterial endosymbionts can do this by causing cytoplasmic incompatibility. They make it so infected females can reproduce with both infected and uninfected males, but uninfected females can only reproduce with uninfected males.* Because the bacteria are passed down from mothers to offspring, that means over time infected females can reproduce more, producing more infected females and males, and they slowly outnumber uninfected individuals. Now, I said “a few”; Wolbachia and Cardinium are the main ones. Researchers in Kentucky have just found another: a strain of Ricketsiella, which isn’t closely related to either of them! This is really exciting for many reasons. For one, Wolbachia has been used to reduce pest populations by releasing tons of sterile males. Maybe we could do a similar thing with the kinds of animals that carry Rickettsiella but not Wolbachia—like…ticks. [Paper 🔓️]
________
* The way the bacteria do this is really fucking cool and we only discovered this, like, three years ago. Infected males’ sperm have a protein that causes chromosomal defects—a kind of “dead man’s switch” that would normally kill the developing embryo. But infected females’ eggs have a protein that turns off that “switch”. I know this is a lot of italics to deal with but I just have to emphasize how fucking cool that is. - Some people are allergic to house dust mites (Dermatophagoides, which literally means “eats skin”, because these microscopic critters eat the tiny flakes of dead skin we shed). The authors of this paper think that Cardinium, one of the mites’ bacterial endosymbionts, might affect their biology and therefore how likely they are to cause allergic reactions. They analyzed the bacteria found in two widespread species of house dust mite: D. farinae and D. pteronyssinus. While D. pteronyssinus had hardly any Cardinium, D. farinae had tons, especially female mites. Interestingly, they also sequenced Cardinium and found that D. farinae mites from the US and China both had the same strain. [Paper] [Sci‑Hub]
Miscellaneous
- The mitochondrial genome of Haemaphysalis flava, the giant panda tick, has been sequenced. This will help people identify H. flava more easily and also clear up how Haemaphysalis species are related. [Paper 🔓️]
- What makes the scorpion Centruroides hirsutipalpus’s venom so powerful? Analyzing the proteins in their venom and the genes that code for them turns up a whole whack of peptides (molecules that make up proteins) that strongly affect sodium and potassium ion channels, the “gates” in cell membranes that help transmit electrical signals between cells. This is how scorpion venom makes animals’—including humans’—nervous systems go haywire. There are also many molecules whose purpose we don’t understand yet. The cool thing is that once we figure out how these molecules affect our cells, we can use them as a base for new medicines.[Paper] [Sci‑Hub]
Taxonomy
Americas
- There’s a tarantula named Sickius longibulbi. SICKIUS LONGIBULBI. S i c k i u s l o n g i b u l b i . Sick long bulb, bro. [Paper]
- Two new cellar spiders from Oaxaca, Mexico: Ixchela panchovillai and I. zapatai—named, of course, after Pancho Villa and Emiliano Zapata. [Paper]
- A new species of erythraeid mite, Leptus guarani, found on a gonyleptid harvestperson from Brazil. As larvae, Leptus mites are parasitic, clinging to various kinds of arthropods—including other arachnids and even other mites. The authors include a very helpful table of Leptus mites and their host species in the Americas. [Paper] [Sci‑Hub]
- Bulb mites (Rhizoglyphus) are agricultural pests that eat, well, bulbs—garlic, onions, and so on. Previously only R. setosus was known to be in Brazil, but now four more have been found. [Paper]
Europe
- The various life stages of a newly described oribatid mite from Norway, Limnozetes solhoyorum, illustrated and photographed—well, micrographed—in exquisite detail. [Paper 🔓️]
- This new species of harvestperson discovered in the Iberian peninsula is kind of like Leiobunum, but also kind of like Nelima. The two genera are poorly defined and the whole family (Sclerosomatidae) needs a thorough reorganization. So with that in mind, it’s been placed in a brand new genus, Leiolima iberica. [Paper 🔓️]
- 22 phytoseiid mites found in Slovenia for the first time, including some known as effective predators of agricultural pests. [Paper 🔓️]
- Here’s the first checklist of Hungarian hard ticks (Ixodidae) published in 60 years. [Paper 🔓️]
Africa
- Five new species of eriophyid mites found causing rust on grass in Egypt. I highly suspect Aceria barnyardi was named that because it was found in a barnyard. ಠ_ಠ [Paper]
- Can you believe this is only the tenth scientific paper on phytoseiid mites of La Réunion Island? La Réunion is a relatively small island (2,500 square km) east of Madagascar, in the Indian Ocean. This survey found 44 species, 17 found on the island for the first time, and 3 new to science. [Paper 🔓️]
Asia
- Three new species of eriophyid mites found infesting wormwood plants in South Khorasan, Iran. [Paper] [Sci‑Hub]
- Three new Torrenticola water mites from Uttarakhand, India. [Paper] [Sci‑Hub]
- Two new species of Cosmolaelaps mites found in Sri Lanka. [Paper]
- A new mite from the family Cunaxidae, Lepidocunaxoides bomiensis, has been found in China. [Paper]
- Four new Mesalgoides feather mites found on four different songbirds from Sichuan, China. [Paper] [Sci‑Hub]
- Two new cellar spiders from southern China: Khorata nani and Khorata yuhaoi. [Paper]
- A new oribatid mite, Dicondyla fossalis, found in Yunnan, China. There’s also an identification guide to all the Dicondyla mites. [Paper]
- Four new species of erythraeid mite larvae from the subfamily Callidosomatinae, found on various planthoppers, treehoppers, etc., from Hainan, China. [Paper] [Sci‑Hub]
- 8 species of phytoseiid mites found for the first time in Vietnam; one new species, Phytoseius tixierae. [Paper 🔓️]
Oceania
- Here’s ten new species of tetragnathids (long-jawed orbweavers), and several more revisions, from Australia, New Zealand, New Caledonia, and Papua New Guinea. And they are beautiful and sparkly! [Paper 🔓️]
As always, thank you for reading! And many thanks to Sebastian Alejandro Echeverri for edits. Suggestions, additions, and corrections are welcome. Just drop us a (silk) line at @arachnofiles. 🕷️
Glossary
- acaricide: a pesticide that kills mites and ticks (Acari).
- biomass: the amount of plant/animal/fungal stuff. One quantitative measure of an ecosystem.
- cytoplasmic incompatibility: a kind of sterility that some bacterial endosymbionts cause in arthropods. The bacteria are only passed down from mother to offspring. They make it so that an infected male can only produce viable offspring with an infected female, and an uninfected female can only produce viable offspring with an uninfected male.
- ecological trap: when animals make poor life choices because they have not adapted to changing conditions. Like when their instincts lead them to lay eggs in totally unsuitable places, eat their favourite plant even if it’s poisonous, and so on.
- endosymbiont: literally “living-with inside”; an organism that lives inside another organism’s cells.
- harvestperson: An arachnid from the order Opiliones. Their head and abdomen are fused, making them look like one big ball with eight legs. Instead of fangs, they have tiny little food scissors that they use to tear up their food into small enough chunks to eat. Sometimes called “daddy long-legs,” though that term is also commonly used to refer to several spider species and crane flies.
- ion channel: a large protein that acts as a kind of “gate” in a cell membrane, letting ions (electrically charged molecules like sodium, potassium, and calcium) in and out. The gate can be shut, allowing these ions to build up on one side. Once there’s a big enough difference in electric charge (voltage) between the two sides of the membrane, the gate quickly swings open. This releases a flood of ions to the other side, creating an electrical current that can be transmitted very quickly between cells. The many types of voltage-gated ion channels are important parts of nerve and muscle cells.
- latrodectism: what black widow (Latrodectus) venom does to you. Classic symptoms are painful muscle cramps and spasms, sweating, nausea, and vomiting. It is rarely fatal, and is usually treated with pain medication or, in severe cases, antivenom.
- peptide: a molecule made of a bunch of amino acids strung together. A bunch of peptides strung together is a protein.
- range: the geographical area a species is found in.
- reservoir: the host that a parasite or germ normally lives inside, usually without causing any symptoms. If the parasite or germ makes the leap to another population or species, it can cause disease.
