Food choice causes interrupted feeding in the generalist grasshopper Schistocerca americana: further evidence for inefficient decision-making

Individual grasshoppers were observed foraging on either single food plant species or binary mixtures of them. Individuals ate slightly less on the mi xtures, but grew faster on them. In the mixtures, individuals fed regularly from both plant species, typically eating both within a single meal. Feedi ng bouts were longer on the preferred plant species in the mixture. The pat tern of foraging behavior was markedly different in mixtures and single foo d treatments. In mixtures, although the total length of time engaged in ing estion over the day was slightly less than in single food treatments, there were relatively more short feeding bouts and more gaps between feeding bou ts within meals, so that the time spent in activities associated with the f ood was markedly longer on mixtures. This is discussed in terms of efficien cy and the problem of choice that faces individual generalists. The efficie ncy factor and its impact on vigilance is added to the other costs of being a polyphagous herbivore. (C) 2000 Elsevier Science Ltd. All rights reserve d.