Scorpionism is one of the main causes of envenomation in humans by arachnids, and it is responsible for numerous cases of morbidity and mortality, especially in the elderly and children (Almeida et al., 2021). Brazil is one of the countries in the world with the highest risk of scorpion stings (Guerra-Duarte et al., 2023). Accidents typically occur in urban areas, especially where scorpions and their prey find suitable conditions to settle, such as cemeteries, trash and debris dumps, and homes with poor infrastructure (Ramires et al., 2011).

Tityus serrulatus (Lutz & Mello, 1922) (Scorpiones: Buthidae), commonly known as the Brazilian yellow scorpion, is one of the main species involved in scorpionism in Brazil (Guerra-Duarte et al., 2023). This species is native to the state of Minas Gerais in southeastern Brazil. However, it is undergoing significant expansion across the Brazilian territory (Ministério da Saúde 2009) due to deforestation and other anthropogenic activities facilitated by its generalist habits and the absence of natural competitors and predators (Lourenço et al., 1996). In this species, females primarily reproduce asexually through parthenogenesis (Braga-Pereira and Santos 2021), so most individuals found are parthenogenetic females.

Due to the increase in scorpionism, understanding natural predators, especially those inhabiting anthropized environments, may be crucial for implementing effective biological control programs for scorpion species that cause serious public health problems (Jared et al., 2020). Therefore, this study aims to report the predation of the Brazilian yellow scorpion T. serrulatus by the toad Rhinella diptycha (Cope, 1862) (Bufonidae) in southeastern Brazil.

On 26 December 2024, feces of R. diptycha were found in an urban environment in the municipality of Ritápolis, state of Minas Gerais, Brazil. The feces were washed in running water and sieved. Rhinella diptycha is the only toad in the urban area where the observation occurred, and its identification was carried out by AAH. Similarly, T. serrulatus is the only urban scorpion in the same region and, moreover, the species had already been reported in a previous record from the same area of this study (see Oliveira et al., 2024).

Upon analyzing the remains of its prey, several fragments of unidentified beetles (Coleoptera) and the presence of three fragments of T. serrulatus (one pedipalp fragment, one metasoma segment, and one telson) were observed (Fig. 1). The parts of T. serrulatus in the feces of R. diptycha suggest that the frog had predated on at least one individual of the scorpion. Based on the size of the fragments found, it is likely that the preyed individual was an adult female.

Fig. 1.: Evidence of predation of Tityus serrulatus by Rhinella diptycha in an urban environment in southeastern Brazil. (a) Example of an individual of T. serrulatus; (b-d) fragments of T. serrulatus recovered from feces of R. diptycha; (b) Pedipalp fragment; (c) - metasoma segment (yellow arrow); (d) Telson (blue arrow); (e) R. diptycha and its feces.

Although amphibians are predators of various invertebrates, evidence of scorpions in their diet are considered scarce. In this sense, Jared et al. (2020) reported that Rhinella icterica (Spix, 1824) (Bufonidae) has the potential to be an effective biological control agent for T. serrulatus which alling with other authors reports in countries such as Venezuela (Tampoa et al., 2024), Colombia (Botero-Trujillo 2006; Flórez D. and Blanco-Torres 2010), and the United States of America (Polis et al., 1981). Rhinella diptycha, a widely distributed species in Brazill (Di Tada and Sinsch, 2023), shares part of its range with T. serrulatus and exhibits synanthropic behavior (Mackenzie and Vladimirova 2022). Its diet is generalist and opportunistic, composed of different prey (Batista et al., 2011), including a record of an unidentified scorpion from the state of Mato Grosso do Sul, Brazil (Severgnini et al., 2020).

The main natural predators of scorpions are owls, lizards, and mice (Guerra et al., 2022); however, these animals are generally absent in urban environments (Lourenço et al., 1996). In Brazil, there it is popularly known that chickens Gallus gallus domesticus (Linnaeus, 1758) are good predators of scorpions (Guerra-Duarte et al., 2023). However, despite there have been promising results, including some immunity of chickens to scorpion venom (Murayama et al., 2022), these birds have diurnal habits, while scorpions are nocturnal (Guerra-Duarte et al., 2023). Therefore, the nocturnal habits of frogs like R. diptycha make them better alternatives for biological control in urban areas. Oliveira et al. (2024) also recorded the predation of an individual of T. serrulatus by the cob-web spider Parasteatoda tepidariorum (C. L. Koch, 1841) (Araneae: Theridiidae) in an urban area of ​southeastern Brazil. Thus, these records reinforce the importance of maintaining and preserving these predators in urban areas for the potential biological control of urban pests that threaten human health.

Since our report was is a single record, new studies may indicate the frequency with which frogs with synanthropic habits feed on scorpions, as well as the feasibility of using these amphibians in the biocontrol of T. serrulatus.