The sterile insect technique (SIT) is a species-specific biological control method that can reduce or eliminate populations of pest insects without the need of chemical pesticides. The technique requires the release of large numbers of sterilized males, which then compete with wild males for female mates to reduce the population (Knipling, 1960; Vreysen et al., 2000; Klassen et al., 1994; Hendrichs et al., 1995; Bloem and Bloem, 1999). Radiation or chemosterilants are typically used to sterilize males for SIT, but these treatments can decrease their ability to compete for mates, which often necessitates the production and release of many more sterile males to increase efficacy (Holbrook and Fujimoto, 1970; Mayer et al., 1998; Helsinki and Knols, 2008). SIT is considered more effective if females are not released (Knipling, 1959; Robinson, 2002), as sterile female insects can still damage crops or transmit disease. Genetic sexing techniques have been developed for some insects, such as the medfly, to preferentially eliminate females before they mature. These typically involve chromosomal translocations that link the male-determining chromosome to a dominant selectable marker, while the females are homozygous for a recessive deleterious gene. Unfortunately, these translocations tend to break down when insects are mass-reared due to male chromosomal recombinations (Franz et al., 1994).
Conventional SIT has been used to control mosquitoes previously (Lofgren et al. 1974), but has not been used extensively due to the limited competitiveness of the sterile males. New transgenic methods, using genetically altered mosquitoes that carry and spread deleterious genes are being developed (Alphey et al, 2010), but the release of genetically-modified insects in many communities/countries may be prohibited or delayed until public opinion and regulatory issues are fully considered.