A BEHAVIORAL MECHANISM FOR INCORPORATING AN UNPALATABLE FOOD IN THE DIET OF A GENERALIST HERBIVORE (ORTHOPTERA, ACRIDIDAE)

We investigated mechanisms that could lead to incorporation of unpalat able foods into the diet of a generalist grasshopper, Schistocerca ame ricana: nutritional stress, habituation, learning, and attraction to n ovelty. The model sl stein involved mesquite, a palatable but inferior food, and mulberry, an unpalatable but adequate food. Nutritional str ess, due to prolonged intake of the inferior food, mesquite, did not i ncrease the acceptability of mulberry. Habituation to the deterrent co mpounds in mulberry and associative learning of the nutritional benefi ts of mulberry also did not occur. However, mulberry became more accep table after a day of restriction to a single food type other than mulb erry, and even deterrent and nutritionally worthless alternatives such as filter paper became acceptable after a day on any one food type. A tendency to feed on novel food types may be a proximate mechanism for the incorporation of relatively unpalatable, but nutritionally valuab le foods into the diet. Novelty and the apparent need for diversity of foods are discussed in the context of exploratory foraging behavior b y generalist herbivores.