Evaluation of Additional Drosophila suzukii Male-Only Strains Generated Through Remobilization of an FL19 Transgene

Abstract

Drosophila suzukii (D. suzukii) (Matsumura, 1931; Diptera: Drosophilidae), also known as spotted wing Drosophila, is a worldwide pest of fruits with soft skins such as blueberries and cherries. Originally from Asia, D. suzukii is now present in the Americas and Europe and has become a significant economic pest. Growers largely rely on insecticides for the control of D. suzukii. Genetic strategies offer a species-specific environmentally friendly way for suppression of D. suzukii populations. We previously developed a transgenic strain of D. suzukii that produced only males on a diet that did not contain tetracycline. The strain carried a single copy of the FL19 construct on chromosome 3. Repeated releases of an excess of FL19 males led to suppression of D. suzukii populations in laboratory cage trials. Females died as a consequence of overexpression of the tetracycline transactivator (tTA) and tTA-activated expression of the head involution defective proapoptotic gene. The aim of this study was to generate additional male-only strains that carried two copies of the FL19 transgene through crossing the original line with a piggyBac jumpstarter strain. Males that carried either two chromosome 3 or a singleX-linked transgene were identified through stronger expression of the red fluorescent protein marker gene. The brighter fluorescence of the X-linked lines was likely due to dosage compensation of the red fluorescent protein gene. In total, four X-linked lines and eleven lines with two copies on chromosome 3 were obtained, of which five were further examined. All but one of the strains produced only males on a diet without tetracycline. When crossed with wild type virgin females, all of the five two copy autosomal strains examined produced only males. However, the single copy X-linked lines did not show dominant female lethality. Five of the autosomal lines were further evaluated for productivity (egg to adult) and male competition. Based on these results, the most promising lines have been selected for future population suppression experiments with strains from different geographical locations.

CRISPR/Cas9-based split homing gene drive targeting doublesex for population suppression of the global fruit pest Drosophila suzukii

“…All transgenic lines and wild-type fly stocks were raised on cornmeal-yeast-agar diet at room temperature (20 to 22 °C) in the open laboratory as described previously ( 62 ). The wild-type colony was established from infested fruit collected from a field in North Carolina in 2011 ( 98 ) and has been periodically augmented with flies collected in North Carolina ( 99 ).…”

“…Repeated releases of sterile males (3 to 5:1 release ratio) into lab cage populations led to effective population suppression. We recently developed fsRIDL D. suzukii strains ( 61 , 62 ) that produce only males when reared on diet without tetracycline. We showed that repeated releases of an excess of fsRIDL males (3 to 10:1 release ratio) led to suppression of small cage populations of D. suzukii .…”

Expansion of the genetic toolbox for manipulation of the global crop pest Drosophila suzukii: Isolation and assessment of eye colour mutant strains

“…Fly rearing, crosses and fecundity/fertility measurements A North Carolina D. suzukii wild-type strain and the established mutant strains were reared on cornmeal-yeast-agar diet at room temperature (approximately 20-22 C), as previously described (Yamamoto et al, 2022).…”

“…Genetic biocontrol offers an environmentally friendly species-specific means for population suppression. Transgenic male-only or female-specific release of insects carrying a dominant lethal (fsRIDL) (Li et al, 2021;Schetelig et al, 2021;Yamamoto et al, 2022), precision-guided SIT (pgSIT) (Kandul et al, 2022), Medea gene drive strains (Buchman et al, 2018) and homing gene drive (Yadav et al, 2023) have been developed for control of D. suzukii populations. In the closely related fly Drosophila melanogaster, the development of transgenic lines is enhanced by the availability of strains carrying a wide variety of visible genetic-markers and other genetic tools such as balancer chromosomes (Miller et al, 2019).…”

Radioactivity and GMO‐Free Sterile Insect Technology for the Sustainable Control of the Invasive Pest Drosophila suzukii

“…[24] Several mass-rearing systems for D. suzukii have already been described [25,26] and various sterilization methods have been proposed and tested [27,28] ) and are currently part of FAO/IAEA guidelines for D. suzukii mass rearing and SIT. Additionally, genetically modified flies have been assessed for both sterilization and sexing, [29][30][31] but EU regulations do not allow the mass release of genetically modified organisms (GMOs) into the environment. Ionizing radiation can also be used for sterilization [32] but it generates radioactive waste and is strictly regulated by the International Atomic Energy Agency (IAEA).…”