Handler A M, Allen M L, Skoda S R
Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida 32608, USA.
Med Vet Entomol. 2009 Jun;23 Suppl 1:98-105. doi: 10.1111/j.1365-2915.2008.00773.x.
The New World screwworm (NWS), Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), was the first insect to be effectively controlled using the sterile insect technique (SIT). Recent efforts to improve SIT control of this species have centred on the development of genetically transformed strains using the piggyBac transposon vector system. Eight transgenic strains were produced incorporating an enhanced green fluorescent protein (EGFP) marker gene under polyubiquitin regulation that has the potential for use as a genetic marking system for released males. The transgenic strains were genetically and phenotypically characterized, including for life fitness parameters and mating competitiveness. These characteristics were unique for each strain and thus some strains were deemed suitable for incorporation into SIT eradication programmes. The strain with the best attributes is designated 'CLAY'. Four of the strains, including CLAY, have been successfully cryopreserved so that their original characteristics should be unchanged when further evaluation is required. With the demonstration of efficient germ-line transformation in NWS, allowing production of fit and competitive transformants, it is now possible to consider further transgenic strain development to improve SIT that are currently being tested in other dipteran species. This includes strains that allow genetic marking with fluorescent proteins, genetic sexing by female lethality, male-specific fluorescent sorting and male sterility by testis-specific lethality. The SIT may also be improved upon by new strategies resulting in lethality of offspring of released insects using conditional lethal systems based upon temperature-dependent or dietary tetracycline regulation of lethal gene expression. Both the creation of new NWS transgenic strains and the ecological safety of their release will be enhanced by new vector systems that allow specific genomic targeting of vector constructs and their subsequent immobilization, ensuring transgene and strain stability.
新大陆螺旋蝇（NWS），嗜人瘤蝇（Cochliomyia hominivorax (Coquerel)）（双翅目：丽蝇科），是第一种采用昆虫不育技术（SIT）有效控制的昆虫。最近为改进该物种的昆虫不育技术控制所做的努力集中在利用piggyBac转座子载体系统开发基因转化品系上。构建了八个转基因品系，这些品系在多聚泛素调控下整合了增强型绿色荧光蛋白（EGFP）标记基因，具有用作释放雄蝇遗传标记系统的潜力。对这些转基因品系进行了遗传和表型特征分析，包括生命适合度参数和交配竞争力。每个品系的这些特征都是独特的，因此一些品系被认为适合纳入昆虫不育技术根除计划。具有最佳特性的品系被命名为“CLAY”。包括CLAY在内的四个品系已成功冷冻保存，以便在需要进一步评估时其原始特性保持不变。随着新大陆螺旋蝇高效种系转化的证明，能够产生健康且有竞争力的转化体，现在有可能考虑进一步开发转基因品系以改进目前正在其他双翅目物种中测试的昆虫不育技术。这包括允许用荧光蛋白进行遗传标记、通过雌性致死进行遗传性别鉴定、雄性特异性荧光分选以及通过睾丸特异性致死实现雄性不育的品系。利用基于温度依赖性或饮食中四环素调控致死基因表达的条件致死系统导致释放昆虫的后代死亡的新策略也可能改进昆虫不育技术。允许载体构建体进行特定基因组靶向并随后固定的新载体系统将增强新的新大陆螺旋蝇转基因品系的创建及其释放的生态安全性，确保转基因和品系的稳定性。
