The "sexual sting": evidence of a coercive behavior in scorpions? (Scorpiones, Bothriuridae)

CARRERA, P. & A. V. PERETTI

San Pedro, San Pablo, Brasil

Congreso; 17th International Congress of Arachnology; 2007

International Society of Arachnology

In the “promenade a deux” in scorpions, during which the male grasp the female and leads her to move together; the male can sting the female by puncturing the female´ s body. This behaviour is called the “sexual sting” and can occur early in the promenade and/ or then sporadically afterward. The behaviour is display usually at the membrane adjacent to the tibia joint of the pedipalp or in the pleural intersegment. Previous studies have suggested that if envenomation occurs during the sexual sting the male may drug the female and thus function to subdue her normal aggressive behaviour. Nevertheless, there is none study testing and analyzing this assumptions. This study is threefold, first determinate the function of the sexual sting by manipulations of the male ability of displaying this behaviour. Second, analysis of the female tegument to determinate if there is perforation during the sexual sting. Finally, the analysis of both sexes behaviours comparing males control with manipulated males. We manipulated the male sting in males of Bothriuridae: Bothriurus flavidus, B. cordubensis and B. bonariensis (N= 10) in two different ways. First we keep the male ability of puncture the female tegument but without venom injection by the obliteration with paraffin of the venom glands’ exit duct (treatment 1). In other group of males, we cut the tip of the sting avoiding the tegument puncture (treatment 2). We found that the male ability of display the sexual sting does not influence the sperm transfer. In 80% of the sexual interactions the female cooperate in front of treatment males and never tried to avoid him. It results very interesting to found that males of both treatment increases the frequency of stimulatory behaviours as “Rubbing with legs” (Kruskall Wallis: X male control = 26; X mT1= 35.03; X mT2= 56.33; Chi square: 0.56 p= 0.04) and “Rubbing with chelicerae” in front of females. Our results suggest that the sexual sting is a ritualized behaviour that not involves tegument puncture and venom injection. Otherwise, the sexual sting is display in front of females that shows intermediate sexual receptivity (terminology in Peretti & Carrera, 2005) characterized by a subtle type of resistance during mating (e.g. movements in a direction contrary to male, etc) but never strong aggressive attack behaviours. As mentioned in previous studies, this female resistance functions as a screening mechanism to favor males according to their stimulatory abilities. Behavioral male coercion may not be possible during scorpions mating because active female cooperation is necessary during the mating.