A twentyfour-hours-lasting tandem in Coenagrion scitulum (Ramb.) in the laboratory (Zygoptera: Coenagrionidae)

In the framework of a research on copulation behaviour in C. scitulum (May-June, 1992). we have reared some individuals in the laboratory, in insectaries as large as 50x50x50 cm, at room temperature and natural photoperiod. Adult Drosophila were constantly available as food. All specimens had been collected as newly emerged tenerals, or as last instar larvae at an artificial pond in Corrubedo, Galicia, NW Spain. About half of the sample died before reaching maturation; all others succesfully emerged and/or matured and mated in their cages, the males (N=42) living on average 16.6 days (maximum age 30). With non-receptive females (those that did not accept copulation), the precopulatory tandem lasted significantly shorter than with receptive ones (x±SE = 19.2 ± 6.7 min; R = 0.6-90; N = 14; and x±SE = 24.3 ± 5.0 min: R = 0.5-136; N – 36; Mann-Whitney U = 4.7, p < 0.001), but in most cases it did not generally exceed the duration of several minutes. However, two males kept their females for as long as 23 h 33 min and 5 h 35 min, respectively. Both these males made repeated invitations to copulate and often attempted to take flight, but since their females were in poor condition and did not perform any copulation or flying movements, often the tandems fell to the ground of the cage. The two females died aflcr a short time while still in tandem.