Hunting Ants in Mediterranean clay soils: Life history of Siagona europaea (Coleoptera, Carabidae)

Abstract

In southern Italy, Siagona europaea is common on clay soils and occurs up to the 38th parallel. Activity recordings have revealed that the beetles are strictly nocturnal. They are resistant to desiccation and prefer temperatures above 30 °C. Their flat body indicates adaptation to life in clay soils, which, in southern Italy, are deeply fissured from April to September. The behaviour of the beetles was observed in a transparent system of cavities consisting of plastic boxes connected by tubes. The beetles feed exclusively on ants that are caught by surprise attack outside their nests. Ants perceive the beetles as being hostile via chemical cues. Single ants then normally retreat, whereas groups of ants attack immediately. The beetles behave unaggressively against cospecifics and rest in groups of various numbers in flat soil crevices. Copulation takes place from the end of April onwards, whereas egg laying occurs from the end of May onwards. The females produce only a few eggs, which are unusually large, and shift them singly in narrow soil cracks. The larvae develop during the summer deep in the soil; they are blind and can be characterized as cave‐life forms by their extremely long cerci and antennae that have a whip‐like unsclerotized sticky distal part.