Caloric restriction extends lifespan of mothers at the expense of offspring survival in a predatory mite (Neoseiulus cucumeris)

The extension of lifespan by means of calorie restriction (CR) is one of the most replicable mechanisms across a range of different taxa. However, the effects of this on the next generation are less studied due to the complexities associated with such an experiment. In this study, the effects of CR and ad libitum (AL) feeding on lifespan, duration of ovipositional stages, and fecundity of a predatory mite, Neoseiulus cucumeris were investigated. The egg volume, sex ratio, and survival rate of the offspring were then compared across the different treatments. The three treatments were: (1) 40 prey Tyrophagus putrescentiae eggs per day representing the AL treatment; (2) 10 eggs per day representing medium CR; and (3) 5 eggs per day being high CR. To assess for transgenerational effects, the eggs produced under the three different treatments were fed AL and reared until adulthood or death. Mothers under the medium CR treatment had a lifespan that almost doubled the lifespan of mothers fed AL. Contrastingly, a higher reproductive rate was seen in mothers under AL, which also had a significantly higher total fecundity when compared with both CR treatments. The AL mothers had a shorter gestational period and produced larger eggs. There was no difference between the sex ratio of offspring for the medium CR and AL treatments. These results indicate the different effects of the two levels of CR and highlight the trade-offs that are accompanied with a longer lifespan due to caloric restriction.