As a first step towards developing genetic option to control pest populations of Gambusia holbrooki, this study investigated the efficacy of oestradiol (E2) to feminise the species. The oestrogen was administered orally via food to neonates (Experiment 1) or embryos through gravid females (Experiment 2) at dosage between 50 and 400 mg kg^–1 of feed. Two control groups consisted of (C1) normal feed and (C2) feed mixed with 70% ethanol. In Experiment 1, 100% feminisation was observed at all E2 concentrations except at 400 mg kg^–1 where no treated individuals survived. There was a significantly (P < 0.05) lower mean survival rate (MSR) of all E2-treated juveniles than of controls (C1: 71.73 ± 22.86%; C2: 70.02 ± 18.26%), with 50 mg kg^–1 showing the best MSR (66.38 ± 12.34%). In Experiment 2, 100% feminisation was achieved at E2 concentrations of 200–400 mg kg^–1 food, with the best MSR (59.33 ± 12.54%) at 200 mg kg^–1 concentration, which was, however, significantly lower than in control groups (C1: 79.96 ± 20.33%; C2: 77.09 ± 10.32%). The reproductive output and gestation period of gravid females were not affected by E2 exposure. The outcomes provide a framework for reliable sex reversal (feminisation) in this fish, paving way for developing genetic strategies to manage and eradicate this pest fish.

作为开发遗传选择以控制Gambusia holbrooki害虫种群的第一步，本研究调查了雌二醇 (E2) 使该物种女性化的功效。雌激素通过食物口服给予新生儿（实验 1）或妊娠雌性胚胎（实验 2），剂量为 50 至 400 mg kg ^–1饲料。两个对照组由（C1）正常饲料和（C2）与70%乙醇混合的饲料组成。在实验 1 中，除了 400 mg kg ^–1没有接受治疗的个体存活外，在所有 E2 浓度下都观察到 100% 女性化。 所有 E2 处理的幼鱼的平均存活率 (MSR)显着 ( P < 0.05) 低于对照组 (C1: 71.73 ± 22.86%; C2: 70.02 ± 18.26%)，50 mg kg^–1显示最佳 MSR (66.38 ± 12.34%)。在实验2中，100％女性化在200-400毫克公斤E2浓度下达到^-1食品，在200毫克公斤最好MSR（59.33±12.54％）^-1的浓度，这是，然而，显著低于对照组（C1：79.96 ± 20.33%；C2：77.09 ± 10.32%）。妊娠雌性的生殖产量和妊娠期不受E2暴露的影响。结果为这种鱼的可靠性别逆转（女性化）提供了一个框架，为制定管理和根除这种有害鱼类的遗传策略铺平了道路。