Directional selection to improve the sterile insect technique: Survival and sexual performance of desiccation resistant strains.

The sterile insect technique (SIT) is an effective, environmentally friendly method for insect control whose success depends on the sexual performance and survival of sterile males. These two parameters are influenced by environmental conditions of target areas, and releasing insects with a higher tolerance to stressful environments can improve SIT efficiency. Directional selection can be used to produce insect strains with higher tolerance to extreme environmental conditions, such as low humidity, for extended periods. We evaluated, under field cage conditions, the sexual competitiveness, sexual compatibility, and survival of strains of (Loew) selected for desiccation resistance to determine the value of directional selection as a possible approach to enhance SIT efficiency. Fly strains (selected and unselected and those mass-reared) were exposed to stressful conditions of low humidity and food and water deprivation for 24 hr before test. As a control, mild conditions without the stressors were used. No differences in sexual competitiveness and sexual compatibility between selected, nonselected, and mass-reared strains were observed when previously exposed to mild conditions. Thus, selection for desiccation resistance does not modified negatively the sexual performance. However, when insects were exposed to stressful conditions, males of selected strains sexually outperform mass-reared males. Additionally, selected strains presented higher survival than mass-reared flies. The approach to integrate directional selection with other technologies in the SIT as well as the implications of using a desiccation-selected strain in the current pest management program is discussed.