Modeling of preferential mating in areawide control programs that integrate the release of strains of sterile males only or both sexes

Abstract

Understanding the principles that govern the mating behavior of insects that are the target of areawide integrated pest management (AW-IPM) programs by using the sterile insect technique (SIT) is a prerequisite to ensure optimal efficiency of such programs. Models were constructed to assess the effect of mating preference of insects, which display a female- or male-choice mating system, on the efficiency of SIT programs that release males only or programs that release both sexes. The model on preferential mating indicated that in a male choice mating system [e.g., screw-worm, Cochliomyia hominivorax (Coquerel) 1, overcoming the discrimination of wild males against mating with sterile females would require a doubling of the number of sterile males compared with male-only releases. The model on female choice was incapable of distinguishing between reduced sterile male competitiveness and female preference for wild males and implied, in addition, that the release of both sexes and male-only releases required the same sterile to wild male overflooding ratio. Operational SIT projects have, however, shown a significant benefit with male-only releases against insects which have a female-choice mating system [e.g., Mediterranean fruit fly, Ceratitis capitata (Wiedemann)], and models were constructed to assess the potential effect of sterile female presence or absence on some parameters, i.e., reduced sterile sperm quantity with remating, reduced sterile sperm quality with aging and incomplete redistribution of the sterile males with the wild insects. The model suggests that in all three cases, male-only releases result in relatively more efficient sterile insects compared with programs releasing both sexes. The results of the models are discussed in relation to data available from operational screwworm and Mediterranean fruit fly AW-IPM programs with an SIT component. © 2006 Entomological Society of America.