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

Abstract

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 Anastrepha ludens (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.

Seasonal variation of the capture and field distribution of sterile Anastrepha ludens in Tamaulipas, Mexico

“…Low levels of rainfall were observed which could lead to low relative humidity in the orchards in the summer. Considering this, desiccation resistance and food search capacity of the sterile flies are determinant factors for their survival in the field (Tejeda et al., ). However, a higher humidity can be provided by a regular irrigation at orchard level when the fruit is still on the trees as is the case for winter and spring.…”

“…As of late, there is an increasing interest on performance issues of sterile A. ludens under field conditions and the optimization of economic resources. Examples of this interest is the development of the genetic sexing strain Tapachula 7 (Tap‐7) or the strains selected based on desiccation resistance under stressful environments (Arredondo, Ruiz, Montoya, & Díaz‐Fleischer, ; Flores et al., ; Orozco, Meza, Zepeda, Solís, & Quintero‐Fong, ; Tejeda et al., ).…”

“…The capture of sterile flies is a useful parameter to evaluate both the survival and coverage of the insect released over the field (Andress, Walters, Toro, & Shelly, 2013;Barry, Blessinger, & Morse, 2004;Hernández, Orozco, Breceda, & Domínguez, 2007). Therefore, environmental conditions in the field play a critical role in the performance of sterile flies such as those reported for wild populations of Ceratitis, Anastrepha, and Bactrocera (Martínez-Ferrer et al, 2010;Tejeda, Arredondo-Gordillo, Orozco-Dávila, Quintero-Fong, & Díaz-Fleischer, 2017;Wang, Johnson, Daane, & Nadel, 2009;Weldom, Yap, & Taylor, 2013).…”

Mapping the spatial variability of the field distribution of sterile Anastrepha ludens over a release area

“…Survival rates and field distribution are quality parameters used to recover information of the field dynamics, competitiveness and quality of the released sterile flies (Hernández, Orozco, Breceda, & Domínguez, ; Thomas & Loera‐Gallardo, ; Utgés, Vilardi, Oropeza, Toledo, & Liedo, ). Besides, issues such as competitiveness and sexual compatibility are addressed in order to improve the field performance of sterile flies regarding wild populations (Orozco‐Dávila, Hernández, Meza, & Domínguez, ; Rull, Brunel, & Mendez, ; Tejeda, Arredondo‐Gordillo, Orozco‐Dávila, Quintero‐Fong, & Díaz‐Fleischer, ). Also, genetic mechanisms have been tested such as the development of Tapachula 7 , a genetic sexing strain of A. ludens targeted to improve the efficiency of sterile flies and reduce costs through the release of males‐only populations (Arredondo, Ruiz, Montoya, & Díaz‐Fleischer, ; Flores et al, ; Orozco, Meza, Zepeda, Solís, & Quintero‐Fong, ).…”

“…In Mexico, continuous efforts are conducted to make more efficient the autocidal control for suppressing A. ludens wild populations. For example, the mass rearing of the unisexual strain Tapachula 7 (Tap‐7), the performance of sterile A. ludens under environmental constraints, or the design of more specialized release machines (Flores et al, ; Mubarqui et al, ; Orozco et al, ; Tejeda et al, ). However, the spatial analysis of the distribution of sterile A. ludens further more than a geographical point may provide results with practical implications in an AW‐IPM approach.…”