A large-scale experiment shows that warmth brings bees and wasps out of hibernation earlier – leaving some of them with poorer starting conditions.
A large-scale experiment shows that warmth brings bees and wasps out of hibernation earlier – leaving some of them with poorer starting conditions. This is particularly true for species in cooler regions that emerge during spring.
Most wild bees hibernate as pupated larvae in their cocoons in the ground, in wood or in other protected places. Species emerging early in spring hibernate as fully developed adults in the cocoon, while species emerging later in summer will still need to finish development during spring.
Climate change is altering the timing of insect emergence after hibernation in spring or summer worldwide. These shifts can have consequences: if insects hatch too early due to higher temperatures, they may not yet find the flowers or prey they feed on. Moreover, hibernating adults burn their essential fat reserves faster under higher temperatures. This can reduce their chances of survival and reproduction.
Read More: University of Würzburg
Image: A red mason bee (Osmia bicornis) in its winter quarters, a reed stalk. When wild bees like this hatch at the right time after a long winter break, they have enough energy reserves left to take flight and find the flowers they need to feed on. But global warming is changing the rules of the game. Warmer springs push insects to emerge earlier, while higher temperatures cause their valuable energy reserves to be used up more quickly during hibernation. This reduces their chances of survival and reproduction. A new study by the University of Würzburg, which examined wild bees and wasps across Bavaria, draws attention to this problem. Dr Cristina Ganuza and Professor Ingolf Steffan-Dewenter show that insects from cooler regions that are active early in the year are particularly vulnerable to warm springs. Under warmer conditions, they hatch too late, leaving them with less energy and poorer starting conditions for successful reproduction. (Credit: Cristina Ganuza / University of Wuerzburg)
