An Empirical Model of Diapause Strategies of the Cricketallonemobius Socius

We modeled the effect of heterogeneity in growing-season length on the diapause strategies of a partially bivoltine population of the striped ground cricket Allonemobius socius. First-generation females of this population can lay mixtures of direct-developing and diapause eggs, and bet-hedging theory predicts that in an unpredictably variable environment the proportion of diapause eggs laid will gradually increase over the season as the likelihood that a second generation will be able to complete development before winter decreases. We quantified variability in the thermal regime using long-term meteorological records, and constructed an analytical model using empirical components for growth and reproduction. The model predicted that females should switch to diapause egg production in early August, a finding that was corroborated by experimental and field observations. The form of the switch between egg types predicted by the model was a transition that spanned only a few days and was similar to that estimated from a laboratory experiment. Thus interannual variation in climate was not sufficient for the evolution of a marked bet-hedging response in the form of a gradual increase in the proportion of diapause eggs. However, we observed considerable variation among females in their diapause strategies that remains unexplained.