Population and individual polyphagy in the grasshopperTaeniopoda eques during natural foraging |
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Authors: | Jerome J Howard David Raubenheimer and Elizabeth A Bernays |
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Institution: | (1) Department of Entomology and Center for Insect Science, University of Arizona, 85721 Tucson, AZ, USA;(2) Department of Zoology, University of Oxford, South Parks Road, OX1 3PS Oxford, UK;(3) Present address: Department of Biological Sciences, University of New Orleans, 70148 New Orleans, LA, USA |
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Abstract: | Dietary patterns of free-foraging individuals of the polyphagous grasshopperTaeniopoda eques Burmeister (Romaleidae) were studied at three desert grassland sites in southern Arizona. At the population level this species
was highly polyphagous at all sites, but showed evidence of selectivity in terms of frequency of feeding relative to frequency
of contacts with resources. Most feeding bouts were very short, suggesting that most plants were relatively unpalatable. Both
diet diversity and the mean length of feeding bouts varied among the study sites, primarily because highly preferred resources
and plant tissues were not encountered with equal frequency at all sites. Individual insects were highly polyphagous. Dietary
overlap calculations showed that insects at a given site generally consumed diets less similar than the resources they contacted.
This result does not support the idea that all insects preferred the same subset of resources. Most differences in diet among
individuals were probably due to environmental heterogeneity, but factors such as sequence of encounter, compensatory feeding
on complementary resources, and intrinsic differences in preference may also have contributed to variation in diets. |
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Keywords: | diet diversity polyphagy Romaleidae Sonoran Desert Taeniopoda eques |
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