Distinctive flavours improve foraging efficiency in the polyphagous grasshopper, Taeniopoda eques

We examined the effect of adding flavours to foods of varying nutritional content on the foraging behaviour of the generalist grasshopper Taeniopoda eques. Each grasshopper received three dishes of food containing either (1) the same nutritionally balanced diet to which distinct flavours had or had not been added; or (2) three nutritionally unbalanced diets (lacking protein, sterol or starch) to which distinct flavours had or had not been added. We found that on the balanced foods, individuals ate similar quantities of food from each dish, but on the unbalanced foods, individuals ate most food from the dish lacking sterol and least of the food lacking protein. The proportions eaten reached a stable level and maximized intake of protein and carbohydrate. Although added flavours had no impact on proportions eaten from the dishes containing balanced food, on the unbalanced foods, individuals attained the stable proportions from the different dishes earlier. Furthermore, addition of flavours in either (1) or (2) resulted in greater food intake overall. On incomplete foods, the addition of flavours resulted in the development of additional oocytes. Thus, addition of diverse flavours enabled the grasshoppers to forage more efficiently, resulting in improvements in performance. These results demonstrate the importance of learning in the foraging efficiency of T. eques.