The Scorpion Files Newsblog

 

Scorpions prey on a diveresity of different preys including members of their own order. In addtion, several scorpion species live in the same habitat and therefore may compete for the same resources (e. g. prey). In settings like this, intraguild predation may occur (that is "the killing and sometimes eating of a potential competitor of a different species" [Wikipedia]).

In a recent article, Şahin Toprak and co-workers reports of three cases of intraguild predation, involving the species Mesobuthus mesopotamicus (Penther, 1912), Compsobuthus matthiesseni (Birula, 1905) and Hottentotta saulcyi (Simon, 1880) in Turkey (all family Buthidae).

Abstract:
Scorpions are predators of a wide range of invertebrates even including other scorpions. Larger species commonly prey on smaller species or juveniles. Here, we report three cases of intraguild predation of Mesobuthus mesopotamicus (Penther, 1912) and Compsobuthus matthiesseni (Birula, 1905) by Hottentotta saulcyi (Simon, 1880) (Scorpiones: Buthidae) in Şırnak Province, Turkey. These are the first cases reporting antagonistic interactions among scorpions in Turkey.

Reference:
Toprak Ş, Kurt R, Yagmur EA. First report of intraguild predation in scorpions (Scorpiones: Buthidae) from Turkey. Euscorpius. 2022(363):1-4. [Open Access]

 

Lizards eat scorpions, and scorpions eat lizards. Even the infamous Tityus C. L. Koch, 1836 (Buthidae) scorpions have their predators. Ray Gabriel and co-workers report that the anole Norops polylepis (Peters, 1874) in Costa Rica catch and eat the scorpion Tityus ocelote Francke & Stockwell, 1987.

Abstract:
A specimen of the anole Norops polylepis (Peters, 1874) observed consuming a female of Tityus ocelote Francke & Stockwell, 1987 in the Parque Nacional Manuel Antonio, Puntarenas Province, Costa Rica is reported. This is the only known natural enemy of this scorpion distributed in southern Costa Rica and northern Panama, and the report also involves the first recorded instance of scorpion predation by N. polylepis.

Reference:
Gabriel R, Burum B, Sherwood D. Predation of Tityus ocelote (Scorpiones: Buthidae) by the lizard Norops polylepis (Sauria: Dactyloidae) in Costa Rica. Revista Iberica de Arachnologia. 2021(38):187-8.

Thanks to Danniella Sherwood for sending me their article.

 

Scorpions are fierce predators that catch and eat many animal groups, but scorpions them self are also on the menu of other predators. In a recent article, Roberto Miranda and co-workers report about a social wasp and ants in Panama that seem to be a predator on Ananteris scorpions.

Abstract:
Two events of predation on Ananteris spp. were observed in the Parque Nacional Darién, Darién Province, Panama. The first case involved the social wasp Agelaia centralis (Cameron, 1907) (Vespidae); the second one, a ponerine ant Leptogenys cf. cuneata Lattke, 2011 (Formicidae). This is the first time that predation by a social wasp on a scorpion is observed. They also represent the first recorded predators for Panamanian Ananteris species.

Reference:
Miranda RJ, de Armas lF, Cambra RA. Predation of Ananteris spp. (Scorpiones: Buthidae) by ants and a social wasp (Hymenoptera: Formicidae, Vespidae) in Panama, Central America. Euscorpius. 2021(329):1-4. [Open Access]

Tomás M. Rodríguez-Cabrera and co-workers have studied instances of predation involving Cuban scorpions from various localities around the island and have compiled a review of all predators reported for scorpions in Cuba in a recently published article.

Abstract:
The ecology of Cuban scorpions is very insufficiently studied and the scarce existing information on their natural enemies is dispersed in the literature. However, scorpions in general are well known to play an important role both as predators and prey in natural ecosystems. Herein we present new instances of predation on different species of scorpions in Cuba, and a review on the topic.

Reference:
Rodríguez-Cabrera TM, Teruel R, Savall EM. Scorpion predation in Cuba: new cases and a review. Euscorpius. 2020(306):1-7. [Open Access]

Scorpions are fierce predator catching many different prey, but they are also hunted by a wide range of predators. It has been reported on several occations that scorpions have been preyed on by theraphosid spiders (aka Tarantulas) and recently Jennifer Duberstein and Dannielle Sherwood have published a research note documenting an Paravaejovis spinigerus (Vaejovidae) being caught and eaten by an Aphonopelma chalcodes Chamberlin, 1940 in Arizona, USA.

Abstract:
No abstract.

Reference:
Duberstein JN, Sherwood D. Predation of Paravaejovis spinigerus (Wood, 1863) (Scorpiones: Vaejovide) by Aphonopelma chalcodes Chamberlin, 1940 (Araneae: Theraphosidae) in Arizona. Arachnology. 2020;18(5):496-8.[Subscription required for full text]

Thanks to Dannielle Sherwood for sending me their article!

Tityus serrulatus Lutz & Mello, 1922 (Buthidae) is one of the world's most venomous scorpions and a public health problem in parts of Brazil. This is an invasive species that has spread to many regions and are also found in urban habitats increasing the probability of human interactions.

Help reducing the populations of this potent species can be found in unusual places. Carlos Jared and co-workers have recently publish an article showing that the “cururu toads” Rhinella icterica (Spix, 1824) capture and eat the deadly Tityus species with great appetite. In addition, the toad seems resistant to the venom of Tityus serrulatus. A group of toads were injected with both letal dose and five-time lethal dose of venom (for mice), but none of the toads died or showed any effects of the venom. Quite a super-toad!

So keeping the toads in your garden or vicinity may be a helpful tool in the biological control of this dangerous scorpion in Brazil.

Abstract:
In recent years, SE Brazil, the most populous region in the country with an estimated population of 88 million, has been experiencing an alarming increase in scorpions accidents (scorpionism), mainly caused by the yellow scorpion (Tityus serrulatus), or “escorpi~ao amarelo” in Portuguese. This species is considered particularly dangerous to humans and can reproduce by parthenogenesis favouring rapid dispersal and colonization of new environments. Since the 1940s, owing to the growing danger represented by scorpionism, public control policies have been developed, including active search for scorpions, together with the use of toxic substances applied in places most likely to serve as their refuges. Even so, the number of accidents is increasing year by year, presently at an alarming rate. It seems evident that the increase in accidents is directly (or primarily) related to the lack of predators that in healthy environmental conditions would naturally control scorpion populations. However, due to environmental changes, leading to a lack of predators, scorpions have been gradually invading the urban environment. Arachnids and insects in general, as well as some other invertebrates, are preyed upon by anuran amphibians (toads, frogs and tree frogs). Toads (family Bufonidae) are nocturnal, large, and highly voracious animals, capable of actively exploring extensive areas and consuming large numbers of insects and arachnids daily. One of the most common toad species in southeastern Brazil is Rhinella icterica. Both R. icterica and T. serrulatus inhabit the same nocturnal environment. The predatory action of toads, specifically on scorpions, is practically unknown from behavioural and toxinological points of view. Thus, we studied the predatory behaviour of this toad against the yellow scorpion and evaluated the resistance of the amphibian to scorpion venom. Our results show that R. icterica is a voracious predator of T. serrulatus and is extremely resistant to its venom. Human/toad relationship throughout western history has always been very conflicted and possibly one of the factors that most has contributed to human ignorance of the role of these amphibians in maintaining ecological balance. Presently, the control of scorpionism is being performed through active search and/or the use of chemical agents, although showing little efficacy in reducing human accidents. In the medium or long term, more effective actions taking into account the biology of scorpions and their predators have never been taken to reduce these accidents.

Reference:
Jared C, Alexandre C, Mailho-Fontana PL, Pimenta DC, Brodie ED, Jr., Antoniazzi MM. Toads prey upon scorpions and are resistant to their venom: A biological and ecological approach to scorpionism. Toxicon. 2020;178:4-7.[Subscription required for full text]

Scorpions and other prey species are involved in a continuing arm race against their predators. The prey will get better in avoidance and defence and the predator tries to get better in overcoming the prey.

Mykola Rasko and co-workers have recently published a study investigating the sting use and venom expenditure during repeated attacks (simulated) in Hadurus arizonensis Ewin, 1928 (Caraboctonidae). Contrary to the projects expectations, the stinging behaviour, venom use and venom volume all decreased as the number of challenges increased. The scorpions defenses actually decreased during repeated attacks. This means that a predator of scorpions should use repeated attacks to overcome a scorpion, and this is also something that has been observed in some predators of scorpions.

Abstract:
Predatore-prey arms races ensure that a prey's defences are well matched with the predator's ability to overcome them. Scorpions have a formidable defensive capacity due to their venomous stinger. Mammalian and squamate scorpion predators overpower scorpions by making repeated attacks. We tested here how scorpions, Hadrurus arizonensis, apply their venom defensively during a simulated repeated attack, consisting of 10 consecutive challenges. Since the persistent repeated attack of a predator, even when stung in the process, seems to indicate its resolve, we expected defensive effort to increase with the number of challenges. We also expected that, owing to the life-and-death nature of a predatory attack, scorpions would be liberal in the use of their venom. We found, however, that stinging behaviour, venom use and venom volume all decreased as the number of challenges increased. Scorpions used only 7.8±9.6% (mean±SD) of their total venom volume during an attack consisting of 10 consecutive challenges. We conclude that a repeated attack seems an effective strategy for scorpion predators to reduce the defensive investment of scorpions.

Reference:
Rasko M, Coelho P, Simone Y, van der Meijden A. How to attack a scorpion: venom metering during a repeated attack. Anim Behav. 2018;145:125-9. [Subscription required for full text]

The Pallid Bat (Antrozous pallidus). Photo: Courtesy by Connor Long (C)

A few weeks ago an article by  Bradley Hopp and co-workers presented a study of the Pallid Bat (Antrozous pallidus) using the Arizona Bark Scorpion (Centruroides sculpturatus Ewing, 1928) as prey. The Arizona Bark Scorpion is the most venomous scorpion in the US, and the researchers observed that the hunting bats were stung by their prey without any serious symptoms.

Systematic observations and experiments with injections of scorpion venom in the bats confirmed that The Pallid Bat is probably resistant to the venom of the bark scorpion. An altered sodium ion channel function may partly be the mechanism for this resistance.

Abstract:
The pallid bat (Antrozous pallidus), a gleaning bat found in the western United States and Mexico, hunts a wide variety of ground-dwelling prey, including scorpions. Anecdotal evidence suggests that the pallid bat is resistant to scorpion venom, but no systematic study has been performed. Here we show with behavioral measures and direct injection of venom that the pallid bat is resistant to venom of the Arizona bark scorpion, Centruroides sculpturatus. Our results show that the pallid bat is stung multiple times during a hunt without any noticeable effect on behavior. In addition, direct injection of venom at mouse LD50 concentrations (1.5 mg/kg) has no effect on bat behavior. At the highest concentration tested (10 mg/kg), three out of four bats showed no effects. One of the four bats showed a transient effect suggesting that additional studies are required to identify potential regional variation in venom tolerance. Scorpion venom is a cocktail of toxins, some of which activate voltagegated sodium ion channels, causing intense pain. Dorsal root ganglia (DRG) contain nociceptive neurons and are principal targets of scorpion venom toxins. To understand if mutations in specific ion channels contribute to venom resistance, a pallid bat DRG transcriptome was generated. As sodium channels are a major target of scorpion venom, we identified amino acid substitutions present in the pallid bat that may lead to venom resistance. Some of these substitutions are similar to corresponding amino acids in sodium channel isoforms responsible for reduced venom binding activity. The substitution found previously in the grasshopper mouse providing venom resistance to the bark scorpion is not present in the pallid bat, indicating a potentially novel mechanism for venom resistance in the bat that remains to be identified. Taken together, these results indicate that the pallid bat is resistant to venom of the bark scorpion and altered sodium ion channel function may partly underlie such resistance.

Reference:
Hopp BH, Arvidson RS, Adams ME, Razak KA. Arizona bark scorpion venom resistance in the pallid bat, Antrozous pallidus. PLoS One. 2017;12(8):e0183215. [Open Access]

Thanks to Matt Simon for informing me about this article.

As previously mentioned in the blog, scorpions have many enemies hunting and feeding on them. Andre Lira and co-workers have now reported about an assasin bug (Heteroptera: Reduviidae) feeding on a Tityus pusillus Pocok, 1893 (Buthidae) in the Brazilian Atlantic Forest. Interestingly, the assasin bug was almost half the size of its scorpion prey. This observation extends the list of invertebrate predators of scorpions.

Abstract:
Litter-dwelling arthropods comprise about three-fourths of the total animal biomass in tropical forests. These invertebrates are involved in many interspecific interactions, from mutualism to predation. We report herein the predation of a scorpion by an immature assassin bug (Harpactorini) during a nocturnal manual search for scorpions in a fragment of the Brazilian Atlantic Forest. The specimens were found 15 cm above the ground on a seedling, and the prey was two-fold larger than the predator. The assassin bug had its rostrum inserted into the pleura of a juvenile Tityus pusillus Pocock, 1893 scorpion, between the first and second segments of the mesosoma; when disturbed, the predator jumped to the leaf litter without releasing its prey. To the best of our knowledge, this is the first report of juvenile predator–prey interactions between a heteropteran and a scorpion in this biome.

Reference:
Lira AFdA, Araujo VLNd, Albuquerque CMRd. Predation of a scorpion (Scorpiones: Buthidae) by an assassin bug (Heteroptera: Reduviidae) in the Brazilian Atlantic Forest. Turkish Journal of Arachnology. 2016;40:294-6. [Open Access]

Thanks to Andre Lira for sending me his article!

Even though scorpions are fierce predators, they also have their own enemies. According to Gary Polis' "The Biology of Scorpions" around 150 taxa have been listed as predators on scorpions. Most of them were vertebrates, but also invertebrates have scorpions on the menu (including scorpions eating scorpions). In a recent research note, Zamani and Rossi reported of a case of intraguild predation where the spider Parasteatoda tepidariorium (C. L. Koch, 1841) caught a male Euscorpius concinnus (C. L. Koch, 1837). The note also discuss other examples of spider predation on scorpions.

Abstract:
We report a case of intraguild predation by the spider Parasteatoda tepidariorum (Theridiidae) on the scorpion Euscorpius concinnus (Euscorpiidae) from Tuscany, Italy. The most interesting aspect is the impressive difference in size between the predator and the prey.

Reference:
Zamani A, Rossi A. Intraguild predation of Euscorpius concinnus (Scorpiones: Euscorpiidae) by Parasteatoda tepidariorum. Arachnida - Rivista Aracnologica Italiana. 2015;1(3):10-3.

Thanks to Alireza Zamani for sending me this article!

Scorpions are generalist predators and it is agreed that one of the greatest predator of scorpions are scorpions themselves. Despite this, interspesific predation in scorpions have rarely been observed in the field (most observations being done in captivity).

Jairo Moreno-Gonzalez and Nicolas Hazzi reported this summer about a case of intraguild predation in Colombia involving a Tityus forcipula Gervais, 1843 feeding on a Chactas vanbenedeni Gervais, 1843.

Abstract:
The first case of intraguild predation in the neotropical region by Tityus forcipula (Gervais) (Buthidae) predating upon Chactas vanbenedeni (Gervais) (Chactidae) in Yotoco Forest Reserve, Valle del Cauca, Colombia, is recorded. A comprehensive table including known records of intraguild predation is provided. Despite similarity between the microhabitats of both species, this observation of predation might be casual.

Reference:
Moreno-Gonzalez JA, Hazzi NA. Intraguild predation case: Tityus forcipula Gervais, 1843 (Scorpiones, Buthidae) feeding on Chactas vanbenedeni Gervais, 1843 (Scorpiones, Chactidae) in Colombia. Revista Iberica de Arachnologia. 2012;20:117-20.

Thanks to Jairo Moreno-Gonzalez for sending me his paper!

Even though scorpions are notorious predators with a venomous sting, they also are prey for other predators including several vertebrate predators like reptiles, birds and mammals. Marc Holderied and co-workers have published an interesting study showing how the Hemprich's long-eared bat (Otonycteris hemprichii) prey on scorpions in Israel.

Interestingly, the bats didn't differ between potent species like Leiurus quinquestriatus and more harmless species like Scorpio maurus, and stings didn't change the bat's behavior and caused no sign of poisoning.

Abstract:
Over 70% of the droppings of the gleaning bat Otonycteris hemprichii can contain scorpion fragments. Yet, some scorpions found in its desert habitat possess venom of the highest known toxicity, rendering them a very dangerous prey. In this study, we describe how O. hemprichii catches and handles scorpions, quantify its flight and echolocation behaviour in the field, investigate what sensory modality it uses to detect scorpions, and test whether it selects scorpions according to their size or toxicity. We confirmed that O. hemprichi is a whispering bat (approx. 80 dB peSPL) with short, multi-harmonic calls. In a flight room we also confirmed that O. hemprichii detects scorpions by their walking noises. Amplitudes of such noises were measured and they reach the flying bat at or below the level of echoes of the loess substrate. Bats dropped straight onto moving scorpions and were stung frequently even straight in their face. Stings did not change the bats’ behaviour and caused no signs of poisoning. Scorpions were eaten including poison gland and stinger. Bats showed no preference neither for any of the scorpion species nor their size suggesting they are generalist predators with regard to scorpions.

Reference:
Holderied M, Korine C, Moritz T. Hemprich's long-eared bat (Otonycteris hemprichii) as a predator of scorpions: whispering echolocation, passive gleaning and prey selection. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2010. Ahead of Print Nov 18. DOI: 10.1007/s00359-010-0608-3. [Subscription required for fulltext]

Carlos Lopez-Gonzalez and co-workers reports that investigations of Mexican Black Bear scats (yes, that's bear pooh ;) show that some bears eat scorpions. The scorpion remains that were found belong to Diplocentrus peloncillensis (Scorpionidae).

In addition, this is the first record of in Diplocentrus peloncillensis in Mexico.

Abstract:
The remains of the scorpion Diplocentrus peloncillensis Francke were found in 7 scats of black bears (Ursus americanus) collected in the Sierra de San Luis, Sonora, Mexico. The collection data and previously reported black bear population estimates for the study area suggested that, although scorpions are not a large part of black bear diets in Sonora, feeding on scorpions is not restricted to a single individual or family unit and is apparently a relatively common behavior in the population. Also, the discovery of D. peloncillensis in Sonora represents a new country record.

Reference:
Lopez-Gonzalez CA, Jones RW, Silva-Hurtado C, Sayago-Vazquez IA. Scorpions are food item of American black bears in Sonora, Mexico. West North Am Naturalist. 2009;69(1):131-3.

Thanks to Oscar Francke for sending me this paper!