Effect of temperature on the defensive and predatory behavior of the scorpion Hadrurus obscurus (Scorpiones: Hadruridae)

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  Effect of temperature on the defensive and predatory behavior of the scorpion Hadrurus obscurus (Scorpiones: Hadruridae) Abstract Scorpions employ their stinging mechanism both for defense and predation, and being ectothermic, temperature influences their physiology and behavior. As such, we hypothesized that temperature both affects defensive stinging and prey-capture behavior in scorpions. We tested the effects of body temperature on these behaviors in the desert hairy scorpion, Hadrurus obscurus Williams, 1970. In the first experiment, scorpions were placed in temperature-controlled chambers with either high (26-28°C) or low (21- 22°C) temperatures and probed to elicit a defensive sting. We recorded the reaction time and the number of probes needed to elicit a sting. In the second experiment, we observed and recorded prey capture behavior at three different temperatures (21, 29, and 33°C). Scorpions with higher body temperatures had faster defensive reaction times and require...

Scorpion Stings and Antivenom Coverage in the Brazilian Amazon

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Scorpion Stings and Antivenom Coverage in the Brazilian Amazon

Abstract

Introduction

Scorpion envenomation in the Amazon causes variable clinical manifestations. Data on these incidents, as well as on the demand, distribution, and use of antivenoms for treatment, are still limited in the literature. This study describes the epidemiology of scorpion envenomation and antivenom coverage in the Legal Amazon area from 2010 to 2020.

Methods

Data on scorpion sting victims, such as sex, age, circumstances of the incident (including location and time), and severity of the case, were obtained from an open health data system called the Notifiable Diseases Information System. The data on antivenom use to treat scorpion stings in each Amazonian state was estimated from consolidated data from the Strategic Inputs Information System.

Results

From 2010 to 2020, 62,388 people were envenomed by scorpions in the Legal Amazon area, resulting in 118 deaths (a fatality rate of 0.19%). The regular distribution of antivenom by the Brazilian Ministry of Health resulted in the allocation of 109,276 vials to the region. However, only 62.2% (of the regional antivenom stockpile 67,994 vials) was used. The state of Pará recorded the highest number of deaths from scorpion stings (33% of total deaths) and the highest use of antivenom per year (∼2705 vials over the 10-y period). Tocantins presented the highest incidence rate, with 119 cases per 100,000 inhabitants.

Conclusion

Although the availability of antivenom in the Legal Amazon between 2010 and 2020 exceeded actual demand, this was not enough to prevent the deaths of 118 victims of scorpion stings. These fatalities primarily affected demographic groups without referral units in their regions and point to critical failures in the spatial distribution of emergency medical services. Rural communities at risk of animal envenomation in the Amazon need timely treatment, a crucial condition for saving lives.

Martins, J. G., Pardal, O., & Procópio, L. (2025). Scorpion Stings and Antivenom Coverage in the Brazilian Amazon. Wilderness & Environmental Medicine. https://doi.org/10.1177_10806032261417950