Data from: Prolonged Diapause in Mormon Crickets: Embryonic Responses to Three Measures of Time

Mormon cricket eggs can remain diapausing in soil for multiple years without forming an embryo. I investigated whether embryonic development was dependent on the number of annual cycles since the egg was laid, duration of the summer period (forcing), or duration of the winter period (chilling). This was a lab experiment conducted at the ARS Northern Plains Agricultural Laboratory in Sidney Montana on two populations: Arizona (AZ, 36.5018 N, 112.1405 W, 2592 m above sea level) and Wyoming (WY, 44.4644 N, 107.4592 W, 2653 m a.s.l). The timing of Mormon cricket egg development was measured for each sibling group (designated mating pairs in the header row) within a population. Hence eggs within sibling groups are considered independent observations, and each sibling group was ultimately analyzed separately. Each sibling group was split into three treatments: 2cycle, 3cycle, and 4cycle (designated 2, 3, and 4 in the data), named for the number of seasonal cycles completed within a 60 week period. Two-cycle is best described as 15 weeks of winter, 3 weeks of spring, 10 weeks of summer, and 2 weeks of autumn; three-cycle is 6 weeks of winter, 2 weeks of spring, 10 weeks of summer, and 2 weeks of autumn; and four-cycle is 6 weeks of winter, 2 weeks of spring, and 5 weeks of summer, and 2 weeks of autumn. For 2cycle and 3cycle, eggs were screened for development in the final two weeks of each cycle (the autumn period), and the developed eggs were separated from the undeveloped eggs. Half-developed eggs (or ‘middies’) were also separated from the undeveloped eggs to follow the completion of their development separately. Initially, eggs in 4cycle were also screened in each ‘autumn’ period, but the embryos were unable to complete development in a single screening. Therefore, we were able to screen 4cycle every other autumn period. For each egg in the sibling group, we tracked the timing of the fate of each egg: either fully developed (and thus ready to enter winter and hatch the following spring), discard (due to being flat, black, or invaded by fungus), broken, mia (or missing in action when accidentally lost), or right censored (for the few eggs in a sibling group that still remained undeveloped at the end of the experiment). Any middies that were found hatched were assumed to have completed development in the prior summer. For some mating pairs, we also collected a few eggs and fixed them, which killed the eggs, but cleared the chorion so that we could review their developmental stages (fate=fixed). The treatments were applied for approximately 10 calendar years starting in 2013 when the eggs were collected and ending in 2023. The timing of the fate of each egg was calculated in three ways: 1) the number of warm periods that the egg had experienced (designated ‘wp’ in the header row), the number of weeks of chill time that the egg had experienced prior to its fate (designated ‘winter chill’), and the number of weeks of warm period that the egg had experienced when its fate was determined (designated ‘summer weeks’ although it also includes the 2 weeks of autumn).

摩门蟋蟀（Mormon cricket）卵可在土壤中滞育多年而不形成胚胎。本研究旨在探究胚胎发育是否取决于产卵后的年度循环次数、夏季时长（促育处理，forcing）或冬季时长（低温处理，chilling）。本实验于美国农业部农业研究服务局（Agricultural Research Service, ARS）北平原农业实验室开展，地点位于蒙大拿州锡德尼，共设置两个种群：亚利桑那种群（AZ，北纬36.5018°，西经112.1405°，海拔2592米）与怀俄明种群（WY，北纬44.4644°，西经107.4592°，海拔2653米）。本研究针对种群内的每个同胞组（表头行中标注为交配对）测定了摩门蟋蟀卵的发育时序。因此，同胞组内的卵视为独立观测样本，且每个同胞组均单独开展分析。每个同胞组被分为三组处理：2循环组、3循环组和4循环组（数据中分别标注为2、3、4），其命名依据为60周周期内完成的季节循环次数。2循环组的周期构成为：冬季15周、春季3周、夏季10周、秋季2周；3循环组为：冬季6周、春季2周、夏季10周、秋季2周；4循环组为：冬季6周、春季2周、夏季5周、秋季2周。针对2循环组与3循环组，研究者在每个循环的最后两周（即秋季时段）对卵的发育情况进行筛查，将已发育卵与未发育卵分离。半发育卵（或称“中间态卵”）也会从未发育卵中分出，以便单独追踪其后续发育完成情况。最初，4循环组的卵也会在每个“秋季”时段进行筛查，但胚胎无法在单次筛查周期内完成发育。因此，研究者改为每隔一个秋季时段对4循环组的卵开展筛查。针对同胞组内的每枚卵，研究者追踪了其最终结局的发生时序：包括完全发育（可进入冬季并于次年春季孵化）、废弃（卵体干瘪、发黑或被真菌侵染）、破损、mia（即行动失踪，指意外丢失的卵），以及右删失（指实验结束时仍未发育的少量同胞组卵）。所有被发现孵化的中间态卵，均被认定为在前一个夏季完成了发育。针对部分交配对，研究者还收集了少量卵并进行固定处理：该操作会杀死卵体，但可清除卵壳以便观察其发育阶段（结局标注为fixed）。该实验处理自2013年收集卵粒起，至2023年结束，共持续约10个日历年。每枚卵的结局发生时序通过三种方式计算：1）卵所经历的温暖周期数（表头行标注为wp）；2）结局发生前卵所经历的低温时长（单位：周，标注为winter chill）；3）结局确定时卵所经历的温暖周期时长（单位：周，标注为summer weeks，该时长亦包含2周秋季时段）。