plasticity Mushroom bodies can change in size throughout the lifespan of an insect. There is evidence these changes are related to the onset of foraging as well as the experience of foraging. In some Hymenoptera mushroom bodies increase in size when nurses become foragers and begin to forage for the colony. Young bees begin as nurses tending to the feeding and sanitation of the hive’s larvae. As a bee ages it undergoes a shift in tasks from nurse to forager, leaving the hive to collect pollen. This shift in job leads to changes in gene expression within the brain which are associated with an increase in mushroom body size. Some butterflies have also been shown to undergo an experience-dependent increase in mushroom body size. The period of greatest increase in brain size typically is associated with a period of learning through experiences with foraging demonstrating the importance of this structure in insect foraging cognition. Mushroom body evolution Multiple insect taxa have independently evolved larger mushroom bodies. The spatial cognition demands of foraging has been implicated in cases where more sophisticated mushroom bodies have evolved. Cockroaches and bees, which are in different orders, both forage over a large area and make use of spatial information to return to foraging sites and central places which likely explains their larger mushroom bodies. Contrast this with a dipteran such as the fruit fly Drosophila melanogaster, which has relatively small mushroom bodies and less complex spatial learning demands. References Further reading Animal cognition Insect behavior