Learning improves growth rate in grasshoppers

To quantify the adaptive significance of insect learning, we documented the behavior and growth rate of grasshoppers (Schistocerca americana) in an en vironment containing two artificial food types, one providing a balanced di et of protein and carbohydrate. which maximizes growth, and the other being carbohydrate-deficient, which is unsuitable for growth. Grasshoppers in th e Learning treatment experienced a predictable environment, where the spati al location, taste, and color of each food source remained constant through out the experiment. In contrast, grasshoppers of the Random treatment devel oped in a temporally varying environment, where the spatial location, taste , and color of the balanced and deficient food types randomly alternated tw ice each day. Our results show that the grasshoppers that could employ asso ciative learning for diet choice experienced higher growth rates than indiv iduals of the Random treatment, demonstrating the adaptive significance of learning in a small short-lived insect.