VARIATION IN POST-MATING BEHAVIOUR IN CAPNIA ATRA MORTON, 1896 (PLECOPTERA: CAPNIIDAE) OBSERVED IN BRITISH AND IRISH POPULATIONS.

Stoneflies (Plecoptera) have complex mating behaviour, but little is known about the species Capnia atra, which is considered rare in both Britain and Ireland given its optimal range in the circumpolar region. Observations of post mating behaviour in non-receptive females, which only mate once, and their conspecific males, was found to differ between British and Irish populations. In the British population non- receptive females were able to communicate effectively with the male, ensuring secondary mating did not occur. In contrast, Irish male C. atra actively attempted to mate with the non-receptive female resulting in a 'rolling ball' as the female manoeuvred her abdomen constantly to avoid copulation. Phenological and ecological variation, previously noted for the species, has likely enabled it to survive well outside its optimal circumpolar range. [ABSTRACT FROM AUTHOR]