Seasonal variations in scorpion activities (Arachnida: Scorpiones) in an area of Caatinga vegetation in northeastern Brazil

Cristiane S Araújo,Denise M Candido,Alexandre Vasconcellos,Helder F P De Araújo,Sidclay C Dias

doi:10.1590/s1984-46702010000300008

Abstract

Seasonal variations in scorpion activity were investigated during a 24 month period in an area of Caatinga (dryland) vegetation in the state of Paraiba, Brazil. The total number of scorpions captured was correlated with climatic variables and prey abundance. Scorpions were captured monthly using pitfall traps; their potential prey was captured using malaise, beating trays and pitfalls. A total of 104 scorpions were captured, representing four species: the bothriurids Bothriurus asper (Pocock, 1893) (n = 74; 71.2%) and B. rochai (Mello-Leitao, 1932) (n = 20; 19.2%), and the buthids Rhopalurus rochai (Borelli, 1910) (n = 4; 3.8%) and Tityus stigmurus (Thorell, 1876) (n = 1; 1.0%). The sex ratios (male:female) of the two most abundant species were 14:1 for B. asper and 7:1 for B. rochai. The abundance of scorpions captured was significantly correlated with precipitation, real evapotranspiration, and abundance of invertebrates (mainly insects). Scorpion activities, especially those of B. asper and B. rochai, may be closely related to their reproductive cycles. Reproduction apparently reaches its maximum when there is an abundance of food, which in the Caatinga is strongly associated with rainfall patterns.

Highlights

Scorpions are common and ecologically important arthropods in arid and semi-arid ecosystems throughout the world (BROWN 2004, POLIS 2001)
Many environmental factors can influence the taxocenoses of scorpions in arid region ecosystems, such as the type of soil, topography, hydrology, food resources, and especially, temperature and precipitation (POLIS 1990, DIAS et al 2006, YAMAGUTI & PINTO-DA-ROCHA 2006)
We investigated the seasonal variations in scorpion activity on the soil surface of an area of caatinga in the State of Paraiba, Brazil, during a period of 24 months

Summary

Introduction

Scorpions are common and ecologically important arthropods in arid and semi-arid ecosystems throughout the world (BROWN 2004, POLIS 2001). They are one of the most important predators in arid region communities in terms of density, biomass and diversity (POLIS 1990); scorpions exert predatory pressure on a wide variety of insect and spider populations, having an impact in the flow of energy of these ecosystems (MCCORMICK & POLIS 1990). We investigated the seasonal variations in scorpion activity on the soil surface of an area of caatinga in the State of Paraiba, Brazil, during a period of 24 months. We have analyzed the correlation between the number of scorpions captured during each month with climatic variables and availability of potential prey

Methods

Results

Conclusion