Variable chemical defence in the checkerspot butterfly Euphydryas gillettii (Lepidoptera: NymphaIidae) |
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| Authors: | M DEANE BOWERS ERNEST H WILLIAMS |
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| Institution: | University Museum and Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, Colorado, U.S.A.;Department of Biology, Hamilton College, Clinton, New York, U.S.A. |
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| Abstract: | Abstract. - 1 Like other checkerspots, Euphydryas gillettii butterflies may contain the defensive chemicals, iridoid glycosides, which are sequestered from their hostplants during larval feeding.
- 2 We analysed the iridoid glycoside content of E.gillettii adults from two different populations, Warm Lake, Idaho, and Granite Creek, Wyoming, that have different patterns of hostplant use.
- 3 Gas chromatographic analysis of thirty butterflies from the Wyoming population showed that they contained a mean of 1.27 (±0.19 SE) % dry weight iridoid glycosides. Notably, 20% of these butterflies contained no detectable iridoid glycosides.
- 4 In contrast, nineteen butterflies from the Idaho population contained a mean of 3.89 (±0.38 SE) % dry weight iridoid glycosides, and all butterflies contained iridoid glycosides.
- 5 These results illustrate how the chemical defence of herbivorous insects varies according to differential use of potential hostplants.
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| Keywords: | Euphydryas gillettii checkerspot butterfly iridoid glycosides unpalatability chemical defence insect-plant interactions |
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