Analysis of the genitalia rotation in the male Anopheles funestus (Diptera: Culicidae).

Anopheles funestus is a major malaria vector in Africa. Insecticide resistance has developed in populations of this species in several African countries, prompting the need to develop additional vector control methods such as the sterile insect technique (SIT). This technique requires an understanding of those underlying physiological events that lead to sexual maturity of An. funestus males, the rotation of their genitalia in particular. The aim of this study was to qualitatively and quantitatively describe genital rotation in An. funestus males as it is an essential function of sexual maturation. Genital rotation of all the males reached its final rotation stage (135-180° rotation) 36 h post emergence at 23 ± 1 °C in laboratory colonised An. funestus males. These males had a comparable rotation rate to wild caught An. funestus at the same temperature setting. A temperature change (either 18 ± 1 °C or 29 ± 1 °C versus 23 ± 1 °C) significantly influenced the genital rotation rate such that this rate increased with increasing temperature. This information enhances our knowledge of the An. funestus male biology. This is important in terms of applying the sterile insect technique as the understanding and manipulation of the rate of sexual maturation in males has implications for the timing of sterile male release.