The influence of some environmental factors on learning and aggregation in locust hoppers

• 1.1. Using the hoppers of two locust species, Locusta migratoria migratorioides (R. & F.) and Schistocerca gregaria Forsk., an attempt was made to study the importance of a patchy physical environment in bringing hoppers together long enough to become habituated to one another.
• 2.2. When offered tethered decoy hoppers in an evenly heated and lighted area, gregarious hoppers spent more time resting near the decoys than solitary hoppers. The test animals reacted in a number of ways when touched by or when touching decoys, and the proportions of the different types of reactions were different in solitary and gregarious hoppers.
• 3.3. When tethered decoy locusts were placed on a warmed spot of the arena floor the behaviour of solitary and gregarious hoppers was almost the same. The time spent grouped near the decoys was increased for both types of test hopper, but far more for solitary than gregarious hoppers. Under these conditions the proportions of the various types of reaction given by the solitary test hoppers was nearly the same as those for the gregarious hoppers.
• 4.4. Solitary Schistocerca test hoppers, allowed to group on a warmed part of the arena floor before testing, showed behaviour typical of gregarious hoppers when placed in an evenly heated arena with decoys. Similarly trained Locusta hoppers showed intermediate behaviour, confirming that Locusta hoppers learn more slowly than those of Schistocerca.
• 5.5. The importance of the experiments to field conditions is discussed.