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Condensed tannin and astringency levels of several grasses known to be preferred, or not preferred, by range caterpillar larvae, Hemileuca oliviae Cockrell, were determined. Comparable levels of a commercially available condensed tannin, quebracho, were applied to filter paper discs in choice-tests. Quebracho inhibited feeding in preference tests. Quebracho also was incorporated into agar-based diets; larval development and survival were inhibited. However, in these latter tests, larvae were not provided with tannin-free diet and responded to the presence of quebracho by increasing their rate of consumption. Condensed tannin (quebracho) therefore acted as a feeding deterrent to range caterpillar larvae in situations where low-tannin hosts were available, but as an antimetabolite in no-choice environments. |
