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]

How much do people living close to scorpions know about the scorpion’s biology and how to deal with envenomations

 

Scorpions and humans are neighbors in many areas, and this is also the case in many towns and regions in Brazil. This cohabitation will sometimes pose challenges, as scorpions may sting humans and some of them are also quite dangerous. There are many articles dealing with this topic, but few articles have studies the general knowledge local peoples have about scorpion biology and treatment of sting cases.

Luiza Eulália de Azevedo Gonzaga and co-workers published last fall a study where adults locals in a few communities in Brazil were asked to answer a questionnaire about their knowledge about the local scorpion fauna. Interestingly, many of the respondents showed quite good knowledge about the local scorpion's ecological and biological characteristics. Quite a few respondents respected the ecological importance of scorpions, but most of them also admitted fear for this group. More than 70% of them had either been stung or knew about somebody been stung by scorpions. The respondents reported both the use of official medicine (e.g., analgesics) and traditional remedies (the article has a list of these). 

The authors recommend community-based conservation programs that should integrate local knowledge with public health strategies to improve the cohabitation between scorpions and humans.

Abstract:
Scorpions are voracious predators that play crucial roles in maintaining ecological balance within food chains. However, they are also notorious for their venom. Understanding ecological knowledge within local populations helps illuminate the intricate relationship between humans and nature. This study investigates the ecological knowledge and uses of scorpion fauna in three municipalities (Caetés, Cumaru, and Limoeiro) in Pernambuco state, Northeast Brazil—primarily engaged in agricultural activities. We administered a 25-question questionnaire, made available online to adult residents, designed to capture their experiences and perceptions regarding these invertebrates. A total of 121 responses were collected (42 from Caetés, 40 from Limoeiro, and 39 from Cumaru). Results revealed that over 70% of participants had either been victims of scorpion stings or knew someone who had experienced scorpionism. Traditional methods, including substances such as milk, alcohol, ice, and even the scorpion itself, were employed in 33% of cases to treat stings, highlighting gaps in public health education regarding venomous sting management. Respondents classified scorpions within the “insect” ethnocategory and used color to distinguish ethnospecies: yellow, red, and black scorpions. Notably, 88.4% of respondents acknowledged the ecological importance of these creatures, while 79.3% admitted fear of them, yet over 60% recognized their significance for humans. This tension underscores opportunities for community-based conservation programs that integrate local knowledge with public health strategies. The alignment between local perceptions and scientific references suggests potential for integrated approaches to mitigate scorpion-related risks while preserving their ecological roles in agricultural landscapes.

Reference:
de Azevedo Gonzaga LE, de Lima JR, da Silva MA, de Moura GJB, de Araujo Lira AF. Traditional ecological knowledge of scorpions in human communities in a Brazilian semiarid region. International Journal of Tropical Insect Science. 2025;Published 27 November 2025. [Subscription required for full text]

Two papers on the venom and venom effect of Tityus species in Brazil

 

As most of you know, there are several medical important scorpions in the Genus Tityus C. L. Koch, 1836 (Buthidae) in Brazil and other countries of South America. Knowledge of the venom composition of dangerous scorpions and their clinical effect is important, both for understanding how they work, but also to develop effective anti-venom therapy. In addition, studying scorpion venom is also important to see if there are components that can be used in medical research.

Last fall there was published two papers on the biochemistry and the effects of the venom of several species of Tityus (and one species of Brotheas C.L. Koch, 1837 in Chactidae). I refer to the abstracts below for further details on these studies.

Paper 1:

Abstract:
Scorpionism is a growing public health concern in Brazil, with the Amazon region presenting the highest mortality rates but remaining understudied, especially regarding local scorpion venoms composition. This study presents the first comprehensive biochemical characterization of venoms from three Amazonian species—Tityus metuendus (TmetuV), Tityus silvestris (TsilvV), and Brotheas amazonicus (BamazV)—using an integrated approach combining Multi-Enzymatic Limited Digestion (MELD)-based bottom-up proteomics, highresolution LC-MS/MS, chromatography, zymography, and enzymatic assays. Tityus serrulatus venom was included as a reference. Significant biochemical differences were observed: TsilvV was rich in 20–30 kDa proteins and showed strong metalloprotease activity; BamazV exhibited high molecular weight proteins and potent phospholipase A2 (PLA2) activity but lacked proteolytic and fibrinogenolytic activities; TmetuV showed the highest hyaluronidase activity and abundance of α-KTx neurotoxins. Zymography revealed a conserved ~45 kDa hyaluronidase in all species. Three novel components were partially characterized: BamazPLA2 (Group III PLA2), Tmetu1 (37-residue α-KTx), and TsilvMP_A (a metalloprotease homologous to antarease). This is the first application of MELD-based proteomics to Amazonian scorpion venoms, revealing molecular diversity and functional divergence within Tityus and Brotheas, emphasizing the need for region-specific antivenoms. These findings provide a foundation for future pharmacological studies and the discovery of bioactive peptides with therapeutic potential.

Reference:
Bordon KCF, Santos GC, Martins JG, Wiezel GA, Amorim FG, Crasset T, et al. Pioneering Comparative Proteomic and Enzymatic Profiling of Amazonian Scorpion Venoms Enables the Isolation of Their First α-Ktx, Metalloprotease, and Phospholipase A(2). Toxins (Basel). 2025;17(8). [Open Access]

Paper 2:

Abstract:
Scorpion stings are considered a neglected condition and represent a serious health problem in many tropical countries, especially for children and the elderly. In Brazil, the yellow scorpion (Tityus serrulatus) is widely found and responsible for the majority of severe envenoming cases; however, other medically relevant species endemic to the Brazilian Amazon region, such as Tityus silvestris, Tityus metuendus and Tityus obscurus, remain underexplored. In the present study, we characterized the clinical, inflammatory and histopathological responses induced by venoms from these Amazonian species in a murine model (Balb/c mice), using T. serrulatus as a reference. Envenomation with T. silvestris resulted in pronounced systemic manifestations, including elevated clinical scores, hyperglycemia, leukocytosis, cytokine release (IL-6, IL-1β, IL-10), and tissue injury in the lungs and kidneys, comparable to the pathophysiological manifestations from T. serrulatus venom. In contrast, T. metuendus and T. obscurus induced milder inflammatory profiles. It is noteworthy that cross-reactivity assays revealed limited immunoreactivity and reduced in vivo neutralization of T. metuendus and T. obscurus venoms by the commercially available T. serrulatus-based antivenom. These findings reveal critical limitations in relying on a single-species antivenom for treating scorpion envenomation across diverse regions and underscore the need for region-specific therapeutic strategies tailored to the distinct venom profiles and pathogenicity of Amazonian Tityus species.

Reference:
Zoccal KF, de Castro Figueiredo Bordon K, Reis MB, Rosa Nunes de Souza Chini PB, Martins JG, Zuanazzi BA, et al. Divergent clinical, inflammatory, and histopathological responses induced by Amazonian Tityus venoms: insights and limitations of current antivenom therapy. Biochimie. 2025;238(Pt B):159–71. [Subscription required for full text]

Thanks to Jonas Martins for sending me the two articles!

Scorpionism in Ecuador - An updated review

 

Scorpion envenomations are a problem in many countries in South America, but a majority of studies have focused on Brazil. A recent article by Adolfo Borges and co-workers shows that also Ecuador is a hotspot for scorpion envenomations in South America.

The study provides an overview of scorpion stings in Ecuador between 2017 and 2021 and the implications in form of deaths and morbidity. The authors also identify taxa of medical importance and their distribution. Unsurprisingly, two species in the genus Tityus C. L. Koch, 1836 (Buthidae) are probably responsible for the most serious cases.  

Abstract:
This study assessed scorpion envenoming risk in Ecuador at provincial and district levels between 2017 and 2021, estimated national incidence and mortality rates, and identified the likely implicated taxa. Data were obtained from the Ministry of Public Health and aggregated by province and district, with incidence and mortality rates calculated per 100,000 inhabitants using annual population estimates. District-level risk was visualized with choropleth maps, and scorpion diversity and distribution were compiled from updated national inventories. A total of 1,514 scorpion stings were reported between 2017 and 2021. National incidence and mortality rates (per 100,000 inhabitants) averaged 1.75 and 0.02. Regional incidence was highest in the Amazonian region (16.81), followed by the coastal (1.39) and Andean highlands (0.66). Hyperendemic districts (≥95th percentile of risk) included Taisha and Tiwintza (Morona Santiago), Arajuno (Pastaza), Flavio Alfaro (Manabí), and La Concordia (Santo Domingo de los Tsáchilas). Mortality was highest in the Amazonian and piedmont coastal regions, with 10 deaths per region and an Amazonian rate of 0.44 per 100,000 inhabitants. These areas are inhabited by Tityus species from distinct morphological and toxinological groups, notably Tityus cf. rosenbergi in western Ecuador and Tityus cisandinus in Morona Santiago and Pastaza. Geographical variation in incidence and mortality likely reflects both the distribution of noxious taxa and population density. Despite high scorpion endemicity (79.2%), a national lethality rate of 1.32% that appears higher than reported in other countries where scorpionism is a public health concern, and the concentration of fatalities in children (75% in ages 1–9), Ecuador still depends on imported scorpion antivenoms, including that prepared against Centruroides species, which show low reactivity to Tityus toxins. These findings highlight the urgent need for preclinical neutralization studies to evaluate local antivenom efficacy and to investigate regional differences in clinical outcomes, to guide future adjustments to immunotherapy based on the biogeographic distribution of medically important Tityus species.

Reference:
Borges A, De Sousa L, Borja-Cabrera GP, Rivera A. Scorpion Envenoming in Ecuador: District-Level Risk, Updated Scorpion Diversity, and Challenges for Treatment and Public Health. Acta Trop. 2025:107942 (In Press). [Subscription required for full text.]

Thanks to Adolfo Borges for informing me about their new article! 

On the occurence of the medically important scorpion Tityus stigmurus in the São Paulo area in Brazil

 

As mentioned in several other posts, the expanding distribution of medical important Tityus C. L. Koch, 1836 (Buthidae) species in Brazil and other South American countries has had an increasing attention, especially because many of these species are also spreading into urban habitats.

Paulo Goldoni and co-workers have recently published an article looking into the distribution of the medically important scorpion Tityus stigmurus Kraepelin, 1898 (Buthidae) in the municipality of Sorocaba, São Paulo in Brazil. The study conforms that this species is introduced and successfully established on this area.

Abstract:
Tityus stigmurus (Thorell, 1876) is among the most venomous scorpion species in Brazil. It occurs mainly in the northeastern region, particularly within the Caatinga biome, where it represents a major public health concern, with several fatal envenomation cases reported. The species has also been recorded as introduced in urban areas of São Paulo, confirming its establishment in a colder and more humid environment than its native range in the country. During the 2010s and 2020s, records of T. stigmurus were also reported from Sorocaba, about 100 km from São Paulo city. Here, we confirm the successful establishment of the species in Sorocaba, based on 53 examined specimens (41 females and 12 juveniles) collected between 1997 and 2025 and deposited in the arachnid collection of the Instituto Butantan (IBSP). Although no envenomation cases have been reported for this species in the municipality, our findings underscore the need for strengthened surveillance of T. stigmurus in Sorocaba and surrounding areas, as this and other Tityus species already confirmed in the region represent a major public health concern.

Reference:
Goldoni PA, Ennser JRP, Iniesta LF, Brescovit AD. Long-term surveillance and monitoring of Tityus stigmurus (Thorell, 1876): a study in the municipality of Sorocaba, São Paulo, Brazil. Studies in Environmental and Animal Sciences. 2025;6(3):e21937.

Thanks to Paulo Goldoni for sending me their article!

 

A new species of Tityus from Ecuador

 

Wilson Lourenco and Elise-Anne Leguin have recently described a new species of Tityus C. L. Koch, 1836 (Buthidae) from Ecuador.

Tityus cuyabeno Lourenco & Leguin.

The article also comments on the distribution of a few other Tityus species in Eucador and the scorpion diversity in this country. 

Abstract: 
A new species of Tityus, subgenus Atreus (Scorpiones: Buthidae) is described from the Province of Sucumbíos in the Ecuadorian Amazonia. Although a noticeable number of studies have been produced on the Ecuadorian scorpion fauna in recent years, many regions of this country remain unexplored. Comments about the remarkable diversity present in Ecuador are addressed and discussed.

Reference:
Lourenco WR, Leguin E-A. New comments on the scorpion diversity of Ecuador and descrption of a new species of Tityus C. L. Koch, 1836 (Scorpiones: Buthidae). Revista Iberica de Arachnologia. 2025(46):27–32. [No full text available]

Thanks to Michiel Cozijn for sending me this article!

Family Buthidae 

Niche partitioning in scorpions across neotropical dry-wet forests in Brazil

 

Species inhabiting the same ecosystem usually tries to find their own niche to avoid competition and predation. A ecosystem with high heterogeneity will probably provides more niches and thereby contribute to a higher diversity.

Andre Felipe de Araujo Lira have recently published an article looking into "spatial niche dynamics of a scorpion assemblage along a dry-wet bioclimatic gradient characterized by sharp transitions in precipitation and humidity regimes" in an area in Brazil.

The study concludes that "spatial niche dynamics of scorpion assemblages along the dry-wet bioclimatic gradient in Brazilian forests are strongly influenced by both microhabitat availability and species ecological specificity". Check out the article for further details.

Abstract:
Understanding spatial niche partitioning can provide useful insights into habitat use, especially in predator assemblages. This study investigated the spatial niche partitioning of scorpion assemblages along a dry-wet bioclimatic gradient in northeastern Brazil, encompassing the Atlantic Forest and two types of Caatinga ecosystems. Using microhabitat presence-absence data from 2692 specimens collected at 20 sites, were quantified niche volumes and overlaps through principal component analysis and kernel density estimation. Results showed that dominant species such as Ananteris mauryi and Tityus pusillus exhibit large niche volumes in the Atlantic Forest, while species distributions and niche breadth vary notably between hypoxerophytic and hyperxerophytic Caatinga. Intraspecific niche overlap was generally high for widely distributed species, reflecting behavioral plasticity and ecological adaptability. Conversely, species with specialized microhabitats exhibited lower niche overlap, indicating niche differentiation. Interspecific overlap varied with ecosystem complexity; high overlaps likely facilitate coexistence through spatial segregation and avoidance of intraguild predation. These findings emphasize the role of microhabitat availability and species ecological traits in shaping niche dynamics, contributing to species coexistence along environmental gradients. The study underscores the importance of habitat heterogeneity for maintaining scorpion diversity and informs conservation efforts aimed at protecting Neotropical dry and wet forest ecosystems.

Reference: 
de Araujo Lira AF. Niche partitioning in scorpions across neotropical dry-wet forests: an intra- and interspecific analysis. Acta Oecologica. 2025;129:104134. [Subscription required for full text]

A biochemical and proteomic study of Amazonian scorpion venoms

 

Studying the venom composition of scorpions is important. It is important to know the venom composition in medical important species to understand their pathological effect and better be able to develop antivenom or treatment. In addition, scorpion venom is a treasure chest filled with different peptides and toxins that can be used to develop medicines. 

Karla Bordon and co-workers recently published a study presenting a comprehensive biochemical characterization of venom from three Amazonian species, Tityus metuendus Pocock, 1897, T. silvestris Pocock, 1897 (both Buthidae) and Brotheas amazonicus  Lourenço, 1988 (Chactidae).

According to the article, "the results suggest a correlation between ecological divergence and venom composition, with implications for both toxicity and antivenom development".

Abstract:
Scorpionism is a growing public health concern in Brazil, with the Amazon region presenting the highest mortality rates but remaining understudied, especially regarding local scorpion venoms composition. This study presents the first comprehensive biochemical characterization of venoms from three Amazonian species—Tityus metuendus (TmetuV), Tityus silvestris (TsilvV), and Brotheas amazonicus (BamazV)—using an integrated approach combining Multi-Enzymatic Limited Digestion (MELD)-based bottom-up proteomics, highresolution LC-MS/MS, chromatography, zymography, and enzymatic assays. Tityus serrulatus venom was included as a reference. Significant biochemical differences were observed: TsilvV was rich in 20–30 kDa proteins and showed strong metalloprotease activity; BamazV exhibited high molecular weight proteins and potent phospholipase A2 (PLA2)
activity but lacked proteolytic and fibrinogenolytic activities; TmetuV showed the highest hyaluronidase activity and abundance of α-KTx neurotoxins. Zymography revealed a conserved ~45 kDa hyaluronidase in all species. Three novel components were partially characterized: BamazPLA2 (Group III PLA2), Tmetu1 (37-residue α-KTx), and TsilvMP_A (a metalloprotease homologous to antarease). This is the first application of MELD-based proteomics to Amazonian scorpion venoms, revealing molecular diversity and functional divergence within Tityus and Brotheas, emphasizing the need for region-specific antivenoms. These findings provide a foundation for future pharmacological studies and the discovery of bioactive peptides with therapeutic potential.

Reference:
Bordon KC, Santos GC, Martins JG, Wiezel GA, Amorim FG, Crasset T, et al. Pioneering Comparative Proteomic and Enzymatic Profiling of Amazonian Scorpion Venoms Enables the Isolation of Their First α-Ktx, Metalloprotease, and Phospholipase A2. Toxins. 2025;17(8):411. [Open Access]

Thanks to Jonas Martins for sending me their article!

The medical importance of Tityus trivittatus in Brazil and its expanding distribution

 

As mentioned in several other posts, the expanding distribution of medical important Tityus C. L. Koch, 1836 (Buthidae) species in Brazil and other South American countries has had an increasing attention, especially because many of these species are also spreading into urban habitats.

 Paulo André Margonari Goldoni and co-workers have recently published an article looking into the epidemiology and expanding urban range distribution of Tityus trivittatus Kraepelin, 1898 (Buthidae) in Parana in Brazil.

The study confirms the need to map the distribution of medical important scorpions in the region and initiate public education programs related to the potential health consequences of scorpion stings. Fortunately, the sting cases examined involved local symptoms only (pain) and no serious cases.

Abstract:
The scorpion genus Tityus Koch, 1836, (Buthidae) includes most of the medically significant species in South America. Tityus trivittatus Kraepelin, 1898 occurs in urban areas and remnants of wet Chaco, Cerrado, and Atlantic Forest in Paraguay and Brazil. Despite a low overall risk of mortality, its wide distribution, parthenogenesis, and synanthropy, pose potential public health concerns. In Brazil, the envenomation cases remain largely unknown. Here we present the first epidemiological reports of this species in Brazil (municipality of Foz do Iguaçu), including new occurrences in the state of Paraná. In addition, we also estimate the spatial factors influencing the records of T. trivittatus in Paraná based on the examined material. A total of 355 specimens were recorded and examined, with proximity to populated areas being the main factor influencing the species sampling bias. For the epidemiological reports, all sting cases involved local pain and occurred typically in feet, hands or legs. All cases were considered successfully treated by the local medical professionals These findings highlight the need for enhanced surveillance of T. trivittatus in southern Brazil.

Reference:
Goldoni PAM, Iniesta LFM, Cequinel JC, Marques-da-Silva E, Brescovit AD. First epidemiological reports and urban range extension of Tityus trivittatus Kraepelin, 1898 (Scorpiones: Buthidae) in Paraná, Brazil. Studies in Environmental and Animal Sciences. 2025;6(2):e18435. [Open Access]

Thanks to Paulo for sending me their article!

Tree-loving scorpions in Costa Rica

 

Scorpions inhabit many habitats and it is known that they also are found on vegetation and tree trunks. However, there are few studies on the ecology of this type of habitat in scorpions. Witold Lapinski recently published an article on the use of tree trunks and vertical distribution by scorpions in a tropical rainforest in Costa Rica. 

Three buthid species were found in the study site and they used almost the entire available height range of the trees in the area. The scorpions were found in stems, branches, and tree trunks.

Abstract:
Many scorpion species can be found on tree trunks but data are scarce regarding their ecology. Therefore, I conducted a two-year survey at a rainforest in Costa Rica. I searched for scorpions at night with a UV light while climbing every month 22 rainforest trees using the rope-climbing technique. The highest trees were ~47 m high. Additional surveys on the forest ground were carried out. Questions: 1) which species occur at the study site? 2) how high above ground do they live? 3) what types of microhabitats do they use, and 4) is their vertical distribution affected by fluctuations of local climate and microclimate? Three buthid scorpion species were found at the study site: Centruroides limbatus, Tityus ocelote, and T. pachyurus. The scorpion species used almost the entire available height range, with T. ocelote occurring significantly higher than the other two species. Most individuals were found on stems, branches, and tree trunks. Effects of local climate and of microclimate fluctuations on vertical distribution were detected only in T. ocelote. Structural variables of trees affected the vertical distribution of all three scorpion species but did not affect their densities.

Reference:
Lapinski W. Vertical distribution and habitat use in arboreal scorpions from a tropical rainforest in Costa Rica. Arachnology. 2025;20(2):303–12. [Subscription required for full text]

First report of the medically significant scorpion Tityus carrilloi in Paraguay

 

As stated in earlier posts, medical important scorpions are expanding their distribution in many parts of South America. Adolfo Borges and co-workers have recently reported the findings of the medical important species Tityus carrilloi Ojanguren-Affilastro, 2021 (Buthidae) in Paraguay. This species has previously only been known from Argentina where it has been involved in severe and fatal envenomations.

Abstract:
We report the first record of the medically important scorpion Tityus carrilloi in Paraguay, from the metropolitan area of Encarnac ´on, Itapúa Department, near the Argentine border. Known for causing severe and fatal envenomings across northern Argentina, the presence of this species in southeastern Paraguay highlights the risk of cross-border dispersion. Along with the regional spread of the Brazilian Tityus serrulatus, this finding has significant epidemiological implications and underscores the urgent need for improved surveillance, diagnostics, and coordinated public health responses in Paraguay and neighboring countries, within the evolving landscape of scorpionism in southern South America.

Reference:
Borges A, Caballero C, Rojas de Arias A, Smith P, Owen M, Nishi A, et al. First report of the medically significant Argentine scorpion Tityus carrilloi (Buthidae) in Paraguay: Epidemiological implications amid rising regional scorpionism. Toxicon. 2025;264:108456. [Subscription required for full text]

Can light with certain colors/wavelengths be used in scorpion control?

 

Scorpions are a health problem in many areas, and especially in Brazil. As mentioned in a previous post, this problem is increasing due to medical important species' expansion into urban habitats. In a recent study, Marina Costa Rodrigues and co-workers tested behavioral reactions in the medical important scorpion Tityus serrulatus Lutz & Mello, 1922 (Buthidae) to light with different colors and wavelengths. 

The authors tested which colors or wavelengths that either attracted or repulsed the scorpions in a test arena. One main finding of the experiments was that the scorpions showed an avoidance to green light and violet light. More studies is necessary to see if lights with these colors can be used in scorpion control to either repel scorpions or attract them into traps.

Abstract:
Scorpions cause 150k+ accidents per year in Brazil. Control of their populations involves manual collection and pesticides. Here we tested if light could be used to attract or repel the yellow scorpion Tityus serrulatus, the main responsible for accidents in the country. Based on previous studies on scorpion´s physiological and behavioral reactions to light, we tested wavelengths that correspond to red, green and violet, controlling temperature, absolute irradiance and electromagnetic stimuli. We built a ring arena divided into 5 parts and had the individuals freely walking in the presence of a light/control. We released the scorpions either away from the LED to test attraction or close to the LED to test repellency. Results showed avoidance to green light, and violet light on a smaller portion, that could be due to wavelengths, since those correspond to primary and secondary response peaks of the animal photoreceptors, due to the absolute irradiance of lights or both. These two wavelengths, therefore, have potential for scorpion control and deserve further investigations.

Reference:
Rodrigues MC, Murayama GP, Moriyama LT, Ximenes N, de Souza L, Willemart RH. Light, camera, action: Behavioral responses of the yellow scorpion Tityus serrulatus to different lights. Behavioural processes. 2025;228:105207. [Subscription required for full text]

Cannibalism in two buthid species from Brazil

 

It is well known that scorpions catch and eat other scorpions (either the same species or other species). Guilherme Melo-dos-Santos and co-workers recently published a study documenting cannibalistic events in the species Rhopalurus laticauda Thorell, 1876 and Tityus silvestris Pocock, 1987 (Buthidae) from Brazil.

Scorpions will eat other scorpions as prey (to get food), but the study also suggests that cannibalism can be part of an intraspecific competition (e.g. competition for territories (microhabitats) or food), that may have a regulatory effect on the populations.

The study was done under controlled captive conditions, but the researchers observed similar behaviors in the scorpions' natural environment. 

Abstract:
Scorpions are predators, with diets ranging from insects to other arachnids. Despite this, their predatory habits, especially in the Brazilian Amazon, are still poorly understood. This study documents, for the first time, cannibalistic events in the species Rhopalurus laticauda Thorell, 1876 and Tityus silvestris Pocock, 1987, both species found in Roraima. The first species is more common in open areas known as lavrado, while the second inhabits humid forests. During the study, we observed that, in most cases, the individuals involved in cannibalistic acts were of similar sizes. Only in one case, an adult preyed on a juvenile. These interactions, frequently associated with territorial disputes and for food, culminated in confrontations in which the weaker individual was subjugated. Our data, obtained under controlled captive conditions, revealed an aggressive and competitive behavior among scorpions of these species. It is important to highlight that similar behaviors were recorded in videos collected during field expeditions, suggesting that cannibalism also occurs in natural environments. The subjugated animals are consumed entirely in many cases, and in others, only parts of the consumed animals were found. These results contribute significantly to the understanding of the population dynamics of scorpions in the Amazon, indicating that intraspecific competition may be an important factor in the regulation of these populations.

Reference:
Melo-dos-Santos G, Melo-dos-Santos G, Leite TM, Rocha AM, Jati SR, Frezarin-da-Silva E, et al. Cannibalistic behavior in Rhopalurus laticauda Thorell, 1876 and Tityus silvestris Pocock, 1897 (Scorpiones: Buthidae) under captivity in the extreme north of the Brazilian Amazon. Revista Chilena de Entomología. 2025;51(2):169–75. [Open Access]

A revision of the expansion of medical important scorpions in human areas in South America

 

South America has several medical important species of Tityus C. L. Koch, 1836 (Buthidae). Interestingly, scorpionism in South America is an urban problem that has been growing in the last decade as the medical species have had expansion of their distribution.

Alexis Emanuel Barrios-Montivero and coworkers have recently published a study presenting an updated overview of the current distribution of six medical important Tityus species. The study have looked at the original distribution of these species and their posterior expansion of synanthropic populations. In addition, the authors have tried to predict the future expansion of these medical important species.

The study shows that there have been a greatly accelerated expansion of medical important species in most cities of Southern South America in recent decades. In addition, they predict that there will be an even greater expansion of several of these species, and more important, they will reach countries and areas where scorpionism is not a problem today.

Abstract:
We revise the expansion of synanthropic medically important species of Scorpions of genus Tityus in southern South America: Tityus bahiensis (Perty 1833), Tityus carrilloi Ojanguren-Affilastro 2021, Tityus confluens Borelli 1899, Tityus costatus (Karsch, 1879), Tityus serrulatus Lutz & Mello, 1922, and Tityus trivittatus Kraepelin 1898, which due to their synanthropic capabilities we regard as invasive species. We also build species distribution models (SMDs) from bioclimatic variables using Maxent. We also included the human density variable in the model, because medically important species in the area are synanthropic, being more common in urban areas than in natural environments. We present their current suitable areas and the potential future distribution up to 2070. According to our analyses most species will expand in the close future, reaching countries without Scorpionism problems, such as Chile and Uruguay. We conclude that, besides synanthropic capabilities, parthenogenesis is the main factor favoring the expansion of some of these species. We also conclude that interactions between invasive Tityus species may hinder their expansion process due to potential competition or exclusion mechanisms.

Reference:
Barrios-Montivero AE, Martínez PA, Ojanguren-Affilastro AA. The Ongoing Expansion of the Medically Important Scorpions in Southern South America. Ecohealth. 2025. [Subscription required for full text]

Thanks to Andres Ojanguren for sending me this article!

Climate change may increase populations of medical important scorpions in Urban areas in Brazil

 

Climate changes are real and they will cause habitat changes that may have an impact on scorpion populations. In Brazil, many species in the medical important genus Tityus C. L. Koch, 1836 (Buthidae) are found in an increasing rate in urban areas. Urban environments provide many advantages for scorpions like hiding places and prey insects and this causes an increase in the number of serious envenomations in Brazil.

Renata de Freitas Barroso and co-workers have recently published a study of the distribution of seven medically relevant Tityus species and they project the potential impacts of climate change on their distribution across Brazil by 2060. The study shows that their scenarios predict a reduction of habitat suitability for some of the study species. Climate-driven habitat reduction may cause a concentration of scorpion populations in densely populated areas, something which probably will increase the rates of human-scorpion contact and become a public health problem.

Abstract:
Urban environments provide Tityus scorpions with abundant prey and shelter, leading to increased humanscorpion encounters and associated public health risks. In this study, we model the distribution of seven medically relevant Tityus species and project the potential impacts of climate change on their distribution across Brazil by 2060. We compiled 1103 occurrence records from the GBIF, iNaturalist, SpeciesLink, and SiBBr databases and applied ecological niche modeling using climate projections for 2041–2060 from WorldClim. Model validation yielded high AUC values, demonstrating a strong agreement between observed distributions and model predictions. Future climate scenarios predict a reduction in Tityus serrulatus habitat suitability. Despite this reduction, models indicate an increase in high-suitability areas, suggesting a possible local expansion in optimal habitats. Conversely, T. metuendus, T. obscurus, and T. silvestris are expected to undergo a significant increase in habitat suitability, potentially expanding into previously unsuitable areas due to temperature and precipitation shifts. Tityus stigmurus is also projected to benefit from climate change with an increase in suitable habitats, although its expansion is more restricted compared to the other species. In contrast, T. bahiensis and T. trivittatus are expected to face a reduction in habitat suitability. These findings highlight that climate-driven habitat reduction may concentrate scorpion populations in densely populated areas, exacerbating public health risks. Therefore, targeted governmental interventions are crucial to mitigate the escalating threat posed by Tityus scorpions in urban settings under climate change scenarios.

Reference:
Freitas Barroso Rd, Cardoso VL, Alves AG, Lira AFdA, Ferreira RG, Costa LF, et al. Climate change increases public health risks from Tityus scorpion stings in Brazil. Toxicon. 2025;258:108326. [Subscription required for full text]

Does the cuticular wax layer in scorpions have a role in mate and sexual recognition in male Tityus pusillus?

 

Male and female scorpions need to be able to recognize each others and their "mood" to ensure safe and optimal mating. The mating dance in scorpions is well known and many studies have indicated that chemical substances are involved in mate and sexual recognition.

Hugo R. Barbosa-da-Silva and co-workers have recently published a study investigating the cuticular wax layer (CWL) involvement in mate and sexual recognition in the buthid Tityus pusillus Lourenço, 2013. The study found some evidence that CWL compounds were involved in sexual recognition, but there was noconfirmation that CWL compounds mediate mate recognition in this species. 

Abstract:
Hydrophobic compounds present in the cuticular wax layer (CWL) of terrestrial arthropods protect them from dehydration and are also involved in chemical communication. However, the role of CWL compounds in the behavioral ecology of scorpions has been studied less often, with most investigations focusing on their responses to mechanical stimuli. In this study, we aimed to characterize the CWL composition of Tityus pusillus (Scorpiones, Buthidae) and examine the influence of CWL solvent extracts and movement on intraspecific mate and sexual recognition by males of this species. We analyzed CWL hexane extracts of adult female and male T. pusillus by gas chromatography-mass spectrometry (GC-MS). In paired behavioral tests inside an experimental arena, we exposed adult males to i) live and intact dead conspecific females; ii) intact dead females and females without the CWL (removed with solvent washes); and iii) intact dead males with and without the CWL. Our results showed that CWL extracts of both female and male T. pusillus contained a series of linear alkanes (C21 – C34; > 54 % relative composition), as well as fatty acyls (> 9.5 %) and methyl-branched alkanes (> 9.1 %). Two unassigned C31 monomethyl-branched alkanes were exclusively identified in male CWL extracts (~ 4.7 %), while female samples contained high relative concentrations (> 22.5 %) of sterol derivatives, present only as minor constituents in male samples. Male T. pusillus performed sexually-oriented behavioral acts when paired with both live and dead conspecific females, intact or without the CWL. However, they ignored conspecific dead males. Our results show that CWL compounds have a role in intraspecific sexual recognition by male T. pusillus but only the CWL compounds does not explain mate recognition.

Reference:
Barbosa-da-Silva HR, Pontes WJT, Lira AFA, Navarro DMAF, Salomão RP, Maia ACD. The role of intraspecific mechanical and chemical signaling for mate and sexual recognition in male Tityus pusillus (Scorpiones, Buthidae). Zoology. 2025;168:126235. [Subscription required for full text]

Thanks to André for sending me their article!

Arm-span competition between males in the buthid scorpion Tityus rosenbergi

 

Courtship and mating behaviors between male and female scorpions are well documented. Intrasexual interactions (between female-female or male-male scorpions) are not mentioned often in the literature. Recently, a new ritualized behavior between the same sex was described and labeled "arm-span competition”.

In a recent article, Jules Thornton Wyman and co-workers present observations of "arm-span competition" between males of Tityus rosenbergi Pocock, 1898 (Buthidae). The behavior is interpreted as a ritualized male-male contests. 

The authors suggest that the elongated pedipalps seen in males of many species might be the result of selective pressure related to ritualized arm-span competition.

Abstract:
Although courtship and mating behaviors have been described for nearly all scorpion lineages, intrasexual interactions in scorpions remain understudied. Recently, a novel ritualized behavioral unit, termed “arm-span competition,” in which individuals face off and extend their pedipalps laterally, was described from analyses of male-male contests in several scorpionid species. Here, we present the first documented observation of arm-span competition in a buthid scorpion, Tityus cf. rosenbergi Pocock, 1898. Interestingly, both T. cf. rosenbergi and most scorpionid species known to engage in arm-span competition exhibit a similar sexual dimorphism: males have markedly longer and more slender pedipalps than females. We suggest that the elongated pedipalps in males of these species might be the result of selective pressure related to ritualized armspan competition. We also highlight the potential for citizen science to contribute rare observations to scientific literature.

Reference:
Wyman JT, Wright-Ueda J, Agnew Q, Castellano I, Simone Y. First report of arm-span competition in buthid scorpions: male-male contest in Tityus cf. rosenbergi Pocock, 1898. The Journal of Arachnology. 2025;52(3):210-3. [Open Access]

Thanks to Yuri for sending me this article!

A new species in the genus Tityus from Colombia is also South America's first venom spraying scorpion

 

A very interesting article was recently published by Leo Laborieux. In this article he describes a new species of Tityus C. L. Koch, 1836 (Buthidae) from Colombia, which is the first venom spraying scorpion reported from South America.

Tityus achilles Laborieux, 2024

Venom spraying has been well documented for several scorpion species as a defense behavior and especially in the African genus Parabuthus (e.g. Parabuthus transvaalicus Purcell, 1899). Interestingly, the new species from Colombia seems to have to types of venom spraying that have different venom use: Flick and Spray. The article discusses the different behaviors and the use of prevenom (cheap) and venom (costly) in T. achilles and compares this to the existing research on venom spraying in Parabuthus. This article brings in new insight into the composition of scorpion venom(s) and the use of it.

Abstract:
Venom is a metabolically expensive secretion used sparingly in a variety of ecological contexts, most notably predation and defence. Accordingly, few animals employ their toxins from a distance, and venom-squirting behaviour is only known from select taxa. In scorpions, species belonging to two genera are known to spray venom when threatened, and previous work in Parabuthus transvaalicus shows that venom delivery depends on perceived levels of threat. Here, I describe Tityus (Tityus) achilles sp. nov., a new species of buthid scorpion from Cundinamarca, Colombia. Remarkably, this species is capable of venom spraying, a first for both the genus and the South American continent. Using frame-by-frame video analysis and ballistic equations, I show that T. (Tityus) achilles sp. nov. employs not one, but two types of airborne defences with dramatic differences in reach and venom expenditure. Further, the new species uses an unusually large reserve of prevenom-like secretion for spraying, as opposed to the costly venom used by other spraying scorpions. In light of these key specializations, I propose that toxungen spraying convergently evolved in response to different selection pressures, laying the groundwork for future investigation.

Reference:
Laborieux L. Biomechanics of venom delivery in South America’s first toxungen-spraying scorpion. Zoological Journal of the Linnean Society. 2024;202(4):zlae161. [Full text supplied by author]

Thanks to Leo and Gerard for sending me this interesting article!

Family Buthidae

A new species of Tityus from Colombia

 

Leo Laborieux just published an article describing a new species of Tityus C. L. Koch, 1836 (Buthidae) from the Cordillera Oriental in Colombia.

Tityus icarus Laborieux, 2024

PS! Check out the the explanation (etymology) for the name chosen for this new species! :)

Abstract:
A new species belonging to the genus Tityus (Atreus) (family Buthidae, C. L. Koch, 1837) is described from the Colombian Cordillera Oriental on the basis of three specimens collected in La Vega (Cundinamarca department). Specimens of Tityus (Atreus) icarus sp. n. were collected in a patch of medium-altitude broadleaf rainforest, 1350 a.s.l. The new species shares affinities with T. (Atreus) antioquensis Lourenço & Otero-Patiño, 1998, and T. (Atreus) nematochirus Mello-Leitão, 1940, but can be readily distinguished from these two taxa based on morphometric differences and a combination of several characters. The new species is the 229th described in the genus.

Reference:
Laborieux L. A new species of Tityus Koch, 1836 (Scorpiones: Buthidae), from the Cordillera Oriental (Colombia). Faunitaxys. 2024;12(41):1-9. [Open Access]

Thanks to Gerard Dupre for sending me this article!

Family Buthidae

Activity patterns of the medical important scorpion Tityus serrulatus in an urban habitat in Brazil

 

Tityus serrulatus Lutz & Mello, 1922 (Buthidae) is probably the most medical important scorpion in Brazil and South America and one of the main reasons for this is the species' opportunistic life style and its adaption to urban habitats.  

José Brites-Neto and co-workers have recently published a study of the activity patterns and reproduction of a population of Tityus serrulatus in a urban habitat in the state of São Paulo in Brazil (in a cemetery). Increased knowledge of this medical important species' behavior and activity is important for those working to prevent scorpion envenomations when humans and scorpions share the same habitat.

Abstract:
Tityus serrulatus Lutz & Mello (Scorpiones: Buthidae) is a scorpion endemic to Brazil adapted to synanthropic life, colonising and proliferating in the most populous urban areas in the country. Here, we evaluated its activity pattern in an urban cemetery in the municipality of Americana, state of S˜ao Paulo, Brazil. Additionally, we tested the effects of species reproduction and climatic seasons on the activity pattern. The Saudade Municipal Cemetery was sampled between 17:00 and 22:00 h during 455 nights from April 2006 to December 2013. The circular mean and the peak of activity were quantified for the total number of specimens, and for specimens with and without broods. Activity patterns were inferred using a rosette diagram. Circular analysis of variance was used to investigate if activity patterns changed across climatic seasons (wet and dry seasons). A total of 25,969 records (467 specimens with broods) were obtained in the field. The circular mean varied between 19:44 and 19:48 h, and the peak of activity occurred between 18:00 and 20:00 h for all groups. Peaks of activity differed from that recorded under laboratory conditions (between 21:00 and 23:00 h). Activity patterns did not differ for specimens with broods, suggesting that the reproductive condition does not alter the species activity pattern. The activity pattern differed between wet and dry seasons for all specimens and specimens without broods, but differences were small and probably biologically irrelevant, probably because the species tolerates a wide variation in abiotic conditions. Deepening the knowledge of the behaviour activity of T. serrulatus can have practical applications for health surveillance agencies, aiming to increase the effectiveness of scorpion control in urban areas.

Reference:
Brites-Neto J, Willmer JNG, Delciellos AC. Activity pattern of Tityus serrulatus (Scorpiones: Buthidae) in an urban area in the state of Sao Paulo, Brazil. Med Vet Entomol. 2024. [Subscription required full text]