Catch fast and kill quickly: do tiger beetles use the same strategies when hunting different types of prey?

BACKGROUND: Tiger beetles (Coleoptera: Cicindelidae) are fast running predatory insects preying on different small insects and other terrestrial arthropods. Prey is located by sight and captured after short and fast pursuit interspersed with pause-and-look behaviour. At least some tiger beetle species can recognise the size and location of prey using memory, which probably allows them to achieve greater hunting success. MATERIAL AND METHODS: Two eurytopic tiger beetle species known to occur in different types of habitat were used in the study: Cicindela hybrida hybrida, a very common central European beetle found even in artificial habitats such as sandy roads or gravel pits, and Calomera littoralis nemoralis, a species widely distributed in southern European countries and occurring on sandy sea beaches, in salt marshes, as well as on sandy banks of rivers and lakes. Both species are very similar in body size. Specimens used in the study were collected in the field and later tested in the laboratory. We checked whether tiger beetles use different hunting strategies when attacking prey of different sizes and abilities to escape as well as whether the sex of the studied species makes a difference in its hunting behaviour. RESULTS: The hunting strategies of both tiger beetle species consist of the following main phases: identification, pursuit (often with stops), attack, and optional release of the prey, and then the secondary attack, abandonment of the prey, or consumption of the prey. Considerable differences were noticed in hunting behaviour depending on the type of prey, its movement ability and escape potential. Caterpillars were attacked without pursuit, in the head or directly behind the head where a concentration of nerves and main muscles responsible for walking are located. Effective attacks on beetles were executed at the connection between the thorax and the abdomen. Calomera littoralis strongly preferred slow moving prey, while Cicindela hybrida preferred in equal measure slow moving prey and medium-sized fast moving prey. The experiment on the preferred size of prey indicated small beetles and small caterpillars as favoured by Calomera littoralis, while Cicindela hybrida preferred medium-sized fast moving prey and large caterpillars. DISCUSSION: The hunting behaviour of Calomera littoralis and Cicindela hybrida is complicated and includes a number of phases allowing to locate, capture and kill the prey. Beetles are able to discriminate between different types of prey and apply different behavioural tactics to hunt it. As the particular strategies are used to increase hunting success, and as a result allow to accumulate energy for future activity of the predator, it can be expected that such a type of hunting behaviour is characteristic also of other tiger beetle species.