Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity. Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1 ± 10.2 (mean ± SD, n = 20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37–54.9%) than normal workers (2–25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0 and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes. Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.

中文翻译：

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入侵性蚂蚁中繁殖工人的起源，行为和遗传

工人繁殖对社交昆虫群落的社会凝聚力和效率具有重要影响，但其在入侵性蚂蚁成功中的作用却被忽略了。我们使用了对233个圈养殖民地的观察，实验室实验和遗传分析，以调查侵入性无节肢动物Anoplolepis gracilipes（黄色蚂蚁）中工人繁殖的条件及其在种间防御中的潜在成本。我们确定了男性劳动生产率的高低，以及是否由女王缺席引发。腹部增大的胃泌乳工人是否更可能生育，正常工人和胃泌乳工人在觅食和防御方面的贡献如何比较；工人生产的雄性和可能是女王生产的或雄性生产的雄性，其大小和杂合性不同。我们的233个圈养殖民地中有66个是雄性，而其中25个中，有些雄性只能由工人生产。具有更多工人的殖民地更可能产生雄性，特别是对于无女王的殖民地。在我们的菌落中，首次出现卵和成年雄性之间的平均天数为54.1±10.2（平均值±SD，n = 20）。在我们的实验室实验中，去除女王后引发了胃胃手术工人比例的增加。体力劳动者的卵母卵母细胞（37–54.9％）比正常劳动者（2–25.6％）更有可能，这是可育或营养性卵产生的指标。在种间攻击试验中，体力劳动者的攻击性较弱，而觅食的劳动者则少于正常劳动者。人工生产的雄性的头宽和翼长平均为4.0和4。来源比未定来源的男性高3％。我们的微卫星DNA分析表明，未确定来源的5.5％的工人生产的雄性和14.3％的雄性是杂合的，这表明在拟南芥中存在二倍体雄性和/或遗传镶嵌。我们的实验工作提供了有关细齿拟南芥工人繁殖及其对殖民地防御的潜在成本的重要信息。如果在原初的皇后和工人生产的雄性之间可以进行巢内交配，则禾本科农杆菌在没有皇后的情况下生产雄性的能力也可能有助于其作为入侵物种的成功。这表明在拟南芥中存在二倍体雄性和/或遗传镶嵌。我们的实验工作提供了有关细齿拟南芥工人繁殖及其对殖民地防御的潜在成本的重要信息。如果在原初的皇后和工人生产的雄性之间可以进行巢内交配，则禾本科农杆菌在没有皇后的情况下生产雄性的能力也可能有助于其作为入侵物种的成功。这表明在拟南芥中存在二倍体雄性和/或遗传镶嵌。我们的实验工作提供了有关细齿拟南芥工人繁殖及其对殖民地防御的潜在成本的重要信息。如果在原初的皇后和工人生产的雄性之间可以进行巢内交配，则禾本科农杆菌在没有皇后的情况下生产雄性的能力也可能有助于其作为入侵物种的成功。