Differences in pedipalp form and size affect courtship behavior in Tityus species

 

Differences in male morphology within the same species have been observed in many species. In a recent paper, Lais Pordeus and Andre Lira show that differences in the male pedipalp chela in Tityus pusillus Lourenço, 2013 (Buthidae) are associated with differences in reproductive behavior. Males with "robust" pedipalp chela performed a higher number of reproductive attempts and female manipulations than than males with "gracile" chela.

Interestingly, the reproductive success of the males in the two groups was quite similar.

Abstract:
This study investigates male pedipalp chela dimorphism and its association with reproductive behaviour in the litter-dwelling scorpion, Tityus pusillus. Using geometric morphometrics, two distinct male morphotypes were identified based on pedipalp chela shape: robust and gracile. These morphotypes were associated with measurable variation in courtship behaviour aspects. Males with robust chelae performed a higher number of reproductive attempts and female manipulations than gracile-chela males, although these differences were not statistically significant. Notably, robust-chela males completed courtship significantly faster than gracile-chelae males (8.03 ± 5.14 minutes vs. 18.40 ± 13.84 minutes), measured as the time until mating successful conclusion. Both morphotypes exhibited similar reproductive success rates (37% and 31%, respectively). These results indicate that robust and gracile differ in courtship dynamics, particularly in courtship duration and patterns of female handling. Variation in female resistance during courtship may help explain why male reproductive behaviours vary. This study documents male chela dimorphism in T. pusillus and reports its correlation with variation in courtship behaviour.

Reference:
Pordeus LM, Lira AFA. Dimorphism in male pedipalps affects the reproductive behaviour in the litter-dwelling scorpion Tityus pusillus Pocock, 1893 (Scorpiones: Buthidae). Invertebrate Reproduction & Development. 2026;Published online 17 Feb 2026. [Subscription required for full text]

Sexual stings in scorpions - knock-out drug or love potion?

 

I have taken the liberty to steal the title of Yuqi Reitsema-Wang and co-workers very interesting review article on sexual stings in scorpion that was published recently. Scorpions use their venom and sting for several purposes like defense and prey capturing. Less known is the sexual stings that have been observed as a part of the courtship for several species of scorpions.

The authors give an introduction to this fascinating behavior in scorpions and discuss what is known about the composition of the venom used in sexual stings (venom metering, prevenom, venom heterogeneity and venom plasticity), how do males control the delivery of venom during sexual stings and how do sexual stings affect the females (are they drugged into submission or is the venom a "love potion" encouraging the females to mate?). In addition, the authors also discuss the evolution of sexual stings in scorpions.

The article is open about not having the answers to the mystery of sexual stings and suggest how to further investigate this special behavior in the future.

Abstract:
Conspecific male to female envenomation, though rare, has been documented across venomous taxa. While traditionally interpreted as a coercive mating strategy to enhance male reproductive success and to avoid cannibalism, this explanation may not fully account for the behaviour in scorpions, which exhibit minor sexual size dimorphism and complex courtship rituals. This review explores the possibly multifaceted roles of sexual stinging in scorpions. We highlight potential adaptive strategies, such as venom metering and compositional plasticity, that allow males to subdue females without causing lethal harm. We discuss hypotheses on the evolution of sexual stings, ranging from sexual coercion to chemical seduction and cooperative signalling. Finally, we propose future research directions, including comparative venomics, behavioural assays, and ecological studies, to shed light on the selective pressures that shape this enigmatic behaviour. By integrating insights from physiology, ecology, and evolution, this review advances our understanding of sexual envenomation as a dynamic interplay between conflict and cooperation in scorpion reproductive strategies.

Reference:
Reitsema-Wang Y, Simone Y, Jenner R, Lüddecke T, Herzig V, Krämer J. Sexual stings in scorpions-knock-out drug or love potion? Frontiers in Arachnid Science. 2025;4:1688532. [Open Access]

Has male Euscorpius scorpions "date drugs" in their venom?

 

Differences in the venom composition of scorpions have been reported for many tears, both within the same species and between species. In addition, different venom types have been related to different purposes (e.g. the findings of prevenom in some species). 

Sex-specific differences in venom composition have been demonstrated for several arthropod taxa(e.g. in spiders where males of the infamous Sydney funnel web spider has a venom lethal to humans, while the female venom is not dangerous). Less is known about this in scorpions, but many species use sexual stings during courship and it has been suggested that the male venom used for this may sedate females to make them less aggressive.

Jonas Krämer and co-workers have recently published an interesting study analyzing the venom composition of male, female and juvenile Euscorpius italicus (Herbst, 1800) (Euscorpiidae). This species uses sexual sting during courtship. Their study shows that the male venom has marked differences in venom composition from females and juveniles. The authors suggest that this may cause a reduced toxic effect on females during the sexual sting. Other suggested effects may be a reduced agggressivity in females and also physiological effects that improove the success of the mating.

More studies are necessary to understand more about this fascinating connection between venom and courtship behavior.

Abstract:
In the animal kingdom, intraspecific variation occurs, for example, between populations, different life stages, and sexes. For venomous animals, this can involve differences in their venom composition. In cases where venom is utilized in the context of mating, the differences in composition might be driven by sexual selection. In this regard, the genus Euscorpius is a promising group for further research, as some of these scorpions exhibit a distinct sexual dimorphism and are known to perform a sexual sting during mating. However, the venom composition of this genus remains largely unexplored. Here, we demonstrate that Euscorpius italicus exhibits a male-specific venom composition, and we identify a large fraction of the substances involved. The sex specificity of venom peptides was first determined by analyzing the presence/absence patterns of ion signals in MALDI-TOF mass spectra of venom samples from both sexes and juveniles. Subsequently, a proteo-transcriptomic analysis provided sequence information on the relevant venom peptides and their corresponding precursors. As a result, we show that several potential toxin precursors are down-regulated in male venom glands, possibly to reduce toxic effects caused to females during the sexual sting. We have identified the precursor of one of the most prominent male-specific venom peptides, which may be an ideal candidate for activity tests in future studies. In addition to the description of male-specific features in the venom of E. italicus, this study also includes a general survey of venom precursors in this species.

Reference:
Kramer J, Pommerening R, Predel R. Equipped for Sexual Stings? Male-Specific Venom Peptides in Euscorpius italicus. Int J Mol Sci. 2022;23(19). [Open Access]

Courtship behavior of the parthenogenetic scorpion Tityus stigmurus from Brazil

 

Most scorpions have sexual reproduction, but a few species seem to have parthenogensis as the main method for reproduction and in these species males are rare. We know very little about the courtship behavior in the species that can reproduce by either method.

Stênio Foerster and co-workers have recently published a study of the courtship repertoire of the Brazilian, parthenogenetic scorpion Tityus stigmurus (Thorell, 1876) (Buthidae), which have sexual populations distributed throughout northeastern Brazil.

Overall, the reproductive repertoire of T. stigmurus was similar to that of other non-parthenogentic scorpions.

Abstract:
Scorpions can adopt different reproductive strategies (e.g., sexual or parthenogenesis) depending on the environmental conditions. In this study, we described the courtship repertoire of the parthenogenetic scorpion Tityus stigmurus, a species with inconspicuous sexual populations distributed throughout northeastern Brazil. Specimens of both sexes (10 male, 10 female) were obtained from field expeditions in three locations in northeastern Brazil and were paired under laboratory conditions in an intrapopulation design. All observations were conducted at night using red light positioned above an experimental arena. From the 10 courtship interactions observed in this study, only one pair successfully completed the reproductive repertoire that included the insemination process. The incomplete interactions were abruptly terminated by the females immediately after deposition of the spermatophore. Overall, the reproductive repertoire of T. stigmurus was similar to that of other scorpions, especially its congeners, possibly because this reproductive behavior emerged at a basal point in the evolution of scorpions. The acquisition of new insights into the reproductive biology of different scorpion species may improve the theoretical background for applications ranging from evolutionary biology to public health strategies.

Reference:
Foerster SIA, Dionisio-da-Silva W, dos Santos AB, de Albuquerque CMR, de Araújo Lira AF. Notes on the courtship behavior of the parthenogenetic scorpion Tityus stigmurus. Acta Arachnologica. 2021;70(2):83-6. [Open Access]

Thanks to Andre Lira for sending me their article!

Sexual stings in scorpion courtship are not just rituals

 

Sexual stings during courtship is probably one of the most fascinating behavior in scorpions. This has been documented in many species, but so far it has not been proven the the male actually penetrate the skin of the female  and if venom is injected. Some authors have characterized this behavior as "a ritual". 

Laura Olguin-Perez and co-workers have recently published a very interesting study on sexual sting in Megacormus gertschi Diaz-Najera, 1966 (Euscorpiidae). The confirm that the male penetrate the female repeatedly in the pedipalp tibia-patella intersegmental membrane just before the promenade a deux part of the courtship starts. They also confirm for the first time that the male actually injects venom into the female during the sexual stinging. Interestingly, the authors also demonstrate that the venom composition in males and females differs.

The combination of these results provide evidence that the sexual sting in scorpion courtships are more than a ritualistic behavior, but seem to have a direct role to ensure a successful courtship and mating. More research is needed to unravel the proximate effects the male venom injection has on the females and their behavior against the male.

Abstract:
The males of the Mexican species Megacormus gertschi Diaz-Najera, 1966 (Scorpiones: Euscorpiidae: Megacorminae) sting the female repeatedly in the pedipalp tibia-patella intersegmental membrane (TPIM) during the initiation of the promenade a deux. It has been suggested that the male’s venom introduced during this ‘‘sexual sting’’ behavior could generate some sedative effect and reduce the possibility of being cannibalized by the female. However, this is unsupported by evidence regarding venom transference. Here, we provide evidence of perforation of the TPIM by the male aculeus and venom transfer during sexual sting performance. We also provide the first venom characterization of this species and show that it has a sexually dimorphic composition. These results, in combination with observations that the sexual sting is displayed in successful matings with non-defensive females, lead us to consider the pre-insemination sexual stinging as a non-genitalic sexual interaction with a potential role as a courtship element.

Reference:
Olguin-Perez L, Francke OF, Carbajal-Saucedo A. Evidence of piercing and sexual differences in venom composition in a sexual stinging scorpion (Scorpiones: Euscorpiidae). J Arachnol. 2021;49:98-107. [Open Access]

Thanks to Oscar Francke for sending me their article!

Observations on the diet and reproduction of Centruroides gracilis from Honduras

 

Centruroides gracilis (Latreille, 1804) (Buthidae) is a widespread scorpion in Central America and Caribbean, but there is little information published on the behavior and ecology of this species. Anna Davison and co-workers have now published an obervational study on the diet and reproduction of this species on Utila Island in Honduras.

Abstract:
The brown bark scorpion Centruroides gracilis (Latreille, 1804) (Buthidae) is an abundant and widespread species, however, fairly little is known about its ecology and natural history. We include several observations from Utila Island, Honduras, that expand on the known literature regarding the diet and reproductive behavior of C. gracilis. We report several prey items for this opportunistic species, which include invertebrates such as spiders (including tarantulas), centipedes, katydids, and crickets; as well as a case of cannibalism between two adult females C. gracilis. We suggest that such cannibalism may be driven by high population densities and/or strong intraspecific competition for prey sources on the island. Additionally, we observed a courtship dance involving a female that still carried second-instar offspring, a common behavior within the Buthidae family, although, to our knowledge, not previously reported for C. gracilis.

Reference:
Davison AM, Brown TW, Arrivillaga C. Notes on the diet and reproduction of the bark scorpion Centruroides gracilis (Scorpiones: Buthidae) on Utila Island, Honduras. Euscorpius. 2020(314):1-7. [Open Access]

 

Mating in scorpions: Better condition = More successful reproduction?

Sexual selection often favors larger body size and/or greater weight in males. Larger males have better condition and are able to perform more impressive courtships, and because of this, will be more attractive for females. This may also be the case in scorpions.

Oliverio and co-workers have published a paper studying mating and courtship behavior in Bothriurus bonariensis (C.L. Koch, 1842) (Bothriuridae) and relating this to the size and body condition of both males and females.

The results showed that better condition (larger size) provided a mating advantage to males (e. g. larger males performed the mating dance quicker than smaller males) and that sexual selection is acting on courtship in B. bonariensis.

Abstract:
In most animal species, body condition has a fundamental role in fitness. In males, sexual selection generally favors larger body size or greater weight. This may result in males with better condition performing more vigorous courtships, and biasing female preferences. The effects of body condition on mating performance have been extensively studied in different animal groups. Among arachnids, scorpions are an interesting group for evaluating the effects of these sexual traits on mating performance, since they exhibit an ancient mode of indirect sperm transfer. Scorpion males deposit a single spermatophore on the soil to transfer the sperm to the females, and therefore, the production of spermatophores involves a high cost for them. In this study, we use the scorpion Bothriurus bonariensis as a model to evaluate different patterns of sexual behavior as a function of the body condition of both males and females. We found that males with a better body condition performed the mating dance stage more quickly than males with a lower condition. In addition, males performed the sexual sting behavior for a longer time with females in a better condition. Our results suggest that a better condition provides a mating advantage to males and represents an indicator of courtship performance. Given that female quality is usually correlated with fecundity, males mating with females with a better body condition probably have higher reproductive success.

Reference:
Olivero PA, Vrech DE, Oviedo-Diego MA, Mattoni CI, Peretti AV. Courtship performance as function of body condition in an ‘ancient’ form of sperm transfer. Animal Biology. 2019;69:33-46. [Open Access]

Thanks to Camilio Mattoni for sending me their article!

Differences in mating behavior between two geographically separated populations of Bothriurus bonariensis

Paola Olivero and co-workers have recently published a study of the mating behavior of two allopatric populations of the Neptropical scorpion Bothriurus bonariensis (C.L. Koch, 1842) (Bothriuridae).

The authors found significant differences in mating patterns, including differences in the frequency and duration of important stimulatory courtship behaviors. Another interesting finding was that most inter-population matings were unsuccessful.

Abstract:
Courtship and mating behavior generally evolve rapidly in diverging populations and species. The adaptation to different environments may cause behavioral divergence in characteristics involved in matechoice. Our objective in this study was to compare the sexual behavior of two distant populations of thescorpion Bothriurus bonariensis. This species has a broad distribution in South America, inhabiting Central Argentina, Uruguay and south-eastern Brazil. It is known that in this species there is a divergence in morphological patterns (body size, coloration, allometry and fluctuating asymmetry indexes) among distant populations. Considering the differences in environmental conditions between localities, we compare the sexual behavior in intra-population and inter-population matings from Central Argentina and southern Uruguay populations. We found significant differences in mating patterns, including differences in the frequency and duration of important stimulatory courtship behaviors. In addition, most inter-population matings were unsuccessful. In this framework, the differences in reproductive behavior could indicate reproductive isolation between these populations, which coincides with their already known morphological differences. This is the first study comparing the sexual behavior of allopatric populations of scorpions; it provides new data about the degree of intraspecific geographical divergence in the sexual behavior of B. bonariensis.

Reference:
Olivero PA, Mattoni CI, Peretti AV. Differences in mating behavior between two allopatric populations of a Neotropical scorpion. Zoology (Jena). 2017; Article in Press. [Subscription required for full text]

Courtship and mating in Scorpiops luridus

Jiao & Zhu has studied courtship and mating in Scorpiops luridus Zhu, Lourenco & Qi, 2005 (Euscorpiidae) and have now published a description of the behavior components involved.

Abstract:
In the current work, the courtship and mating of Scorpiops luridus Zhu Lourenço & Qi, 2005 (Euscorpiidae) from Xizang province (Tibet), China, were studied for the first time in the laboratory. Most of the mating behaviors in Scorpiops luridus are not remarkably different from those exhibited by other scorpions. However, for the first time a male pulling a female with its chelicerae to rapidly accomplish the sperm uptake was observed. Additionally, the sexual stinging behavior displayed by the male occurred in the initial stage, not during the promenade stage as previously described in several scorpion species. Through observation and analysis, we speculate that venom injection during sexual stinging is selective, possibly relying on the status shown by the stung scorpion (passive or aggressive). In order to clearly describe the process of courtship and mating, both sequences are represented in a flow chart, while the main behavior components of these processes were identified, analyzed and discussed.

Reference:
Jiao GB, Zhu MS. Courtship and mating of Scorpiops luridus Zhu, Lourenco & Qi, 2005 (Scorpiones: Euscorpiidae) from Xizang Province, China. Journal of Venomous Animals and Toxins. 2010;16(1):155-65. [Free fulltext]

Family Euscorpiidae

Courtship and mating in Heterometrus petersii

Jiao & Zhu has recently published a study on mating behavior and courtship in the Asian scorpion Heterometrus petersii (Scorpionidae). The study confirms most previously observed behavior components in other species (suggested readings: Polis & Sissom (1990), Benton (2001), Tallarovic et al. (2000) and Ross (2009)).

Heterometrus is a popular genus for captive breeding, and this paper is interesting for those that want to breed scorpions in this genus.

Abstract:
Courtship and mating in Heterometrus petersii (Thorell, 1876) (Scorpiones: Scorpionidae) was observed in the laboratory. In this paper the behavior components displayed in courtship and mating are identified, analyzed and discussed.

Reference:
Jiao G-B, Zhu MS. Courtship and mating in Heterometrus petersi (Thorell, 1876) (Scorpiones: Scorpionidae). Euscorpius. 2009; (84):1-5. [Free fulltext]

Suggested Readings:
Polis, G. A. & W. D. Sissom. 1990. Life history. Pp. 161–223 in G. A. Polis (ed.) The Biology of Scorpions. Stanford, CA: Stanford University Press.

Benton, T. G. 2001. Reproductive ecology. Pp. 288–294 in Brownell, P. H. & G. A. Polis (eds.) Scorpion Biology and Research. New York, NY: Oxford University Press.

Tallarovic, S. K., J. M. Melville & P. H. Brownell. 2000. Courtship and mating in the giant hairy desert scorpion, Hadrurus arizonensis (Scorpionidae, Iuridae). Journal of Insect Behavior, 13(6): 827–838.

Ross, L. K. 2009. Notes and observations on courtship and mating in Tityus (Atreus) magnimanus Pocock, 1897 (Scorpiones: Buthidae). Journal of Venomous Animals and Toxins Including Tropical Diseases, 15(1):43–53.

Family Scorpionidae

Two new papers on the reproduction in Tityus magnimanus

My friend Luc Ross has now published two papers dealing on various aspects of the reproduction of the Venezuelan buthid Tityus magnimanus Pocock, 1897.

Abstracts:
The frequency of spermatophore production and the amount of time between matings for laboratory-reared males of Tityus (Atreus) magnimanus to regenerate spermatophores were examined. Males attain sexual maturity at the fifth or sixth instar (after a period of 137 to 155 days) and can produce initial spermatophores shortly after maturation. After mating, males can regenerate spermatophores within a single 24-hour period and remate. The present contribution represents the first report on an aspect of reproductive biology in this species and is part of a continuing study of the life history and post-embryonic development of Tityus (Atreus) magnimanus.

Courtship and mating behaviors of the scorpion Tityus (Atreus) magnimanus are herein described, consisting of various components that pertain to four distinct behavioral stages. The courtship and mating rituals of Tityus (Atreus) magnimanus are similar to those of other scorpions. Behavioral components are presented in an ethogram to demonstrate their occurrence during mating sequences. The current report is presented as observational data that were acquired during life history studies of this species.

Referenences:
Ross LK. Frequency of spermatophore production and regeneration in the males of Tityus (Atreus) magnimanus Pocock, 1897 (Scorpiones, Buthidae). Journal of Venomous Animals and Toxins Including Tropical Diseases. 2009 2009;15 (1):157-62.

Ross LK. Notes and observations on courtship and mating in Tityus (Atreus) magnimanus Pocock, 1897 (Scorpiones: Buthidae). Journal of Venomous Animals and Toxins Including Tropical Diseases. 2009 2009;15 (1):43-53.

Family Buthidae