Nests are special locations for social insects to store food and rear brood. A nest is a unique location unlike all other locations. The survival of social insects depends on the ability of foragers to navigate back to a nest after a trip to collect resources.
For insects that do not make nests, no one location is of unique importance to survival. Numerous locations may contain equally suitable resources and the need to navigate back to the same resource is not as critical. Can insects that do not have nests orient to unique locations using landmarks?
A group of scientists* asked Drosophila flies this question by creating a unique location of importance to the flies. They built an arena with a floor made of tiles. The temperature of each tile could be individually controlled. One tile in the arena was held at a temperature suited to long term survival. All the other tiles were kept at an unsuitably warm temperature. The tile floor was surrounded by walls containing patterns useful as landmarks.
Naive flies released into the arena eventually located the one suitable tile within 5 minutes through random movements. In subsequent trials, Drosophila flies located the suitable tile in less time and with more direct path. If the landmarks were moved by rotating the arena walls, no learning occurred. They concluded that Drosophila flies can and do use landmarks to navigate to unique locations. Navigation using landmarks may be a widespread ability in insects and not solely confined to those that have nests.
Ousted TA, Zuker CS, Reiser MB. 2011. Visual place learning in Drosophila melanogaster. Nature 474:204–7.