Termination of copulation and associated behaviour in Culicoides melleus (Coq.) (Diptera, Ceratopogonidae)

Abstract

The nature and age dependence of behaviour of Culicoides melleus (Coq.) during and immediately after separation from copulation has been examined. Differences in the timing of events during separation, and consequent retention of the spermatophore, were ascribed to interplay of three factors: (i) the existence of age-dependent physiological mechanisms in both male and female that ‘time’ the course of copulation, (ii) female kicking behaviour which acts as a stimulus causing the male to release his claspers, and (iii) after clasper release, the separatory kicking performance of the female and simultaneous attempts by the male to free the spermatophore's capsule lodged in his genitalia. Post-separatory behaviour of both male and female was age-dependent, but only that of the male was influenced by the presence of the spermatophore. A retained spermatophore caused abdominal grooming to be initiated significantly more frequently as the first action after separation, and to occupy the insect for a substantially larger proportion of its time for the first two minutes after separation. In insects of both sexes, abdominal grooming was the dominant activity after separation giving way to grooming of other bodily parts and locomotory activity. Both young and old males and old females removed a retained spermatophore usually within 40 s of separation. Only very young females performed poorly in this respect, with spermatophores kept usually for at least several minutes and, in some instances, several hours.