Comparison of trophic behavior of scorpions Mesobuthus eupeus, Mesobuthus caucasicus, Androctonus crassicauda (Scorpiones, Buthidae)
The diet of three species of scorpions of the Buthidae family: the mottled scorpion (Mesobuthus eupeus (C. L. Koch, 1839), the Caucasian scorpion (Mesobuthus caucasicus (Nordmann, 1840), and the fat-tailed scorpion (Androctonus crassicauda (Oliver, 1807) was researched. Field research was conducted on a semi-desert territory in the foothills of the South-Eastern slopes of the Lesser Caucasus (within the Nakhchivan Autonomous Republic of Azerbaijan), where all three studied scorpion species live syntopically. The taxonomic composition and number of eaten objects were identified by their chitin fragments found in long-used scorpion shelters, and by visual detection of preys on predator chelicerae. To assess the significance of certain objects in the diet of scorpions, the index of electivity was calculated. Six classes of invertebrates have been recorded in scorpion food: worms, mollusks, crustaceans, arachnids, millipedes and insects. The basis of the diet of all three types of scorpions were insects. Mesobuthus eupeus had a relatively wider range of food than M. caucasicus and A. crassicauda, but it lagged behind them in the biomass of eaten prey. The main hunting strategy for A. crassicauda leading a predominantly burrowing lifestyle was to wait for prey in ambush inside the shelter. The M. caucasicus more often used the strategy of random search on the surface. The M. eupeus was distinguished by using a wide variety of waiting and searching strategies. Differences in the feeding spectra of scorpions are presumably associated with different degrees of electivity to certain groups of food and features of the food-gathering behavior of each of the species under consideration. The main criteria for selecting food items were presumably their morpho-ecology parameters (size and shape of prey, degree of its mobility, type of movement).