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

<p dir="ltr">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<b> </b>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).</p>

Tags: diapause, environmental-cue, katydids, multiannual-lifecycle, phenology
Organization: Department of Agriculture