Pitts-Singer Theresa L
USDA ARS Pollinating Insects Research Unit, Logan, UT.
Environ Entomol. 2020 Apr 14;49(2):516-527. doi: 10.1093/ee/nvaa004.
Megachile rotundata F. populations are managed to pollinate alfalfa, Medicago sativa L. (Fabaceae), for seed production in western North America. Some progeny produced in summer by overwintered M. rotundata females enter diapause as prepupae to overwinter and become adults the following year. Other offspring avert diapause to undergo adult emergence in summer. The regulatory mechanism(s) of diapause induction or aversion is unknown; the process apparently involves multiple and integrated factors. This 4-yr study sought to determine effects of the exposure of mother bees to short, long, very long, and natural photoperiods on their production of non-diapausing and diapausing progeny. Just-emerged adult bees from both Utah and Canada sources were exposed to different photoperiods for 3 d in incubators and then released into field enclosures placed over blooming alfalfa. Control bees were those exposed to only outdoor conditions. Reproduction was monitored for each female bee, and offspring diapause outcome was recorded. Progeny outcome data were informative for only two of the four study years. Generally, progeny of Utah mothers exposed to long and very long photoperiods were more likely to be non-diapausers compared to progeny of mothers exposed to short and control photoperiods. Short and long (but not very long) photoperiod maternal exposures increased the likelihood of diapause aversion in Canada progeny. Performing multiyear field studies on geographically distinct populations is imperative for revealing environmental challenges and inconsistent bee performance that can impair analyses and interpretation. Future similar studies are needed to more fully evaluate photoperiod effects on diapause.
在北美洲西部，为了紫花苜蓿（Medicago sativa L.，豆科）种子生产进行授粉，人们对切叶蜂（Megachile rotundata F.）种群进行管理。一些越冬后的切叶蜂雌性个体在夏季产生的后代以预蛹的形式进入滞育状态越冬，并在次年成为成虫。其他后代则避免滞育，在夏季羽化成为成虫。滞育诱导或避免的调控机制尚不清楚；这个过程显然涉及多个综合因素。这项为期4年的研究旨在确定母蜂暴露于短、长、极长和自然光照周期下对其非滞育和滞育后代产生的影响。来自犹他州和加拿大的刚羽化的成年蜜蜂在培养箱中暴露于不同光照周期3天，然后放入放置在盛开紫花苜蓿上的田间围栏中。对照蜂只暴露于户外条件。监测每只雌蜂的繁殖情况，并记录后代的滞育结果。在四个研究年份中，只有两年的后代结果数据具有参考价值。一般来说，与暴露于短光照周期和对照光照周期的母蜂后代相比，暴露于长光照周期和极长光照周期的犹他州母蜂后代更有可能是非滞育个体。短光照周期和长光照周期（但不是极长光照周期）的母体暴露增加了加拿大后代避免滞育的可能性。对地理上不同的种群进行多年田间研究对于揭示可能影响分析和解释的环境挑战和蜜蜂表现不一致情况至关重要。未来需要进行类似研究，以更全面地评估光照周期对滞育的影响。
