approaches, the male tucks his abdomen under his body with his abdominal pouches still inflated and wings still vibrating. Once the female is within of the male, the male will begin a series of head movements. Within 1–2 seconds of head movement initiation, the male begins rhythmically wing its fannings and moves closer to the female. Once close enough, the male then leaps onto the females back and begins copulation. Females It has been shown that during mating, females experience a switch in olfactory-mediated behaviors. Specifically, virgin females prefer the pheromones of sexually developed males over the host fruit odor. Females exhibit this preference until mating occurs, following which they prefer the host fruit odor. This finding has been evidenced by a specific protein, CcapObp22, that shows approximately 37% identity with the pheromone binding protein of Drosophila melanogaster. In a recent study, this protein was shown to bind male pheromone components, specifically farnesene, a highly strong hydrophobic terpene. Genetics Sex determination in C. capitata is by the typical XY system. Unusually for a dipteran and for a frugivore, medflies do not have an opsin gene for blue light perception as shown from the whole-genome sequencing project completed in September 2016. In a study done by Spanos et al. in 2001, researchers were able to sequence the entire mitochondrial genome of the fly. They found that the genome was 15,980 base pairs long with 22 tRNA genes and 13 genes encoding mitochondrial proteins. Using this information, researchers were able to use this genome sequence as a diagnostic tool for population analysis and a method to determine the source of recent introductions. Immunity and disease transmission In a 1987 study completed by Postlethwait et al., researchers assessed the immune response of the medfly using bacterial inoculation. After inoculating the medfly with Enerobacter cloacae, the researcher extracted the haemolymph from the males and found that it contained potent antibacterial factors compared to the haemolymph of controls. Through further testing, they were able to show that these potent factors were generated within 3 hours of inoculation and lasted for approximately 8 days. This finding indicated that medflies do have an adaptive immune response that is similar to the Drosophila melanogaster. Since it has been established that C. capitata is a cosmopolitan pest that affects hundreds of commercial and wild fruit species, considerable research has been done to assess the medfly's ability to transmit diseases.