Reproductive strategies and sexual conflict in the bed bug Cimex lectularius
In this thesis I examine the reproductive strategies of the bed bug Cimex lectularius, a traumatically inseminating insect. In Chapter 21 examine the mating behaviour of C. lectularius, including the mating rates of males and females. Remating rates were very high, with females mating with 5 different males during a single reproductive bout. Males copulated for longer with virgin females than non-virgins. Sperm competition was predicted to be an important determinant of male reproductive success, because the ejaculates of an average of 5 males will be concurrent in the female's reproductive tract during a reproductive bout. In Chapter 3 the different gamete allocation strategies used by males were examined. Males allocated more sperm to virgin females than to non-virgins. Sperm migration and storage by females was examined in order to provide a basis from which mechanisms of sperm competition could be predicted. In Chapter 4 the patterns of sperm precedence were examined and a hypothetical mechanism of sperm competition was tested experimentally. Sperm precedence appears to favour the last male to mate due to a positional effect in the spermalege of the last ejaculate inseminated. In Chapter 5 the effect of high mating rates on females was assessed experimentally. Females mating at a high rate were found to die earlier than females mating at an artificially low rate. There was no difference in the rate of egg production of females between these two groups, so females mating at a low rate had a higher lifetime reproductive success. Appendix I investigates the potential benefits females may gain from polyandry. Both direct benefits of mating and a suite of possible fitness traits were assessed. However, no detectable differences in number or quality of offspring were uncovered. Chapter 6 reviews the evidence for a conflict of interest between the sexes over the remating rate and the possible causes of this conflict.