Title

Quantifying host plant requirements in Speyeria butterflies

Poster Number

36

Lead Author Major

Pre-Pharmacy, Biological Sciences, and Pre-Dentistry

Format

Poster Presentation

Faculty Mentor Name

Ryan Hill

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Over the past century, human disturbance has led to decreases in populations of Speyeria butterflies and their native Viola hosts (Hammond, 1983). Sensitivity of Viola to human disturbance has been shown to be a large contributor to the decline in Speyeria, which play vital roles in their complex ecosystems. While Speyeria larvae are known to feed on Viola, other aspects of their larval ecology are not well understood. In order for Speyeria habitats to be sufficiently restored, an understanding of the Viola requirements necessary to sustain a butterfly population is imperative. In order to elucidate how many butterflies a specific habitat could support, the amount of host plant required to obtain a viable adult was quantified. Wild S. callippe and S. hydaspe females were obtained, and oviposition was induced in a bag containing dried host Viola. Viola papilionacea was used as a lab host because it is a readily available surrogate for wild California Viola, and its morphology is conducive to image analysis and measurement. Total leaf area consumed by all individuals was averaged to obtain an estimate of leaf area necessary for Speyeria larvae to reach adulthood. Our results indicate that larvae consume from 160 - 226 cm^2 of leaf area. Estimates of Speyeria population size and Viola leaf area available in the habitat are not currently known. Once these data are obtained, they will be used in conjunction with the amount of leaf area consumed to identify target levels of population size in populations where restoration is needed.

Location

DeRosa University Center, Ballroom

Start Date

20-4-2013 1:00 PM

End Date

20-4-2013 3:00 PM

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Apr 20th, 1:00 PM Apr 20th, 3:00 PM

Quantifying host plant requirements in Speyeria butterflies

DeRosa University Center, Ballroom

Over the past century, human disturbance has led to decreases in populations of Speyeria butterflies and their native Viola hosts (Hammond, 1983). Sensitivity of Viola to human disturbance has been shown to be a large contributor to the decline in Speyeria, which play vital roles in their complex ecosystems. While Speyeria larvae are known to feed on Viola, other aspects of their larval ecology are not well understood. In order for Speyeria habitats to be sufficiently restored, an understanding of the Viola requirements necessary to sustain a butterfly population is imperative. In order to elucidate how many butterflies a specific habitat could support, the amount of host plant required to obtain a viable adult was quantified. Wild S. callippe and S. hydaspe females were obtained, and oviposition was induced in a bag containing dried host Viola. Viola papilionacea was used as a lab host because it is a readily available surrogate for wild California Viola, and its morphology is conducive to image analysis and measurement. Total leaf area consumed by all individuals was averaged to obtain an estimate of leaf area necessary for Speyeria larvae to reach adulthood. Our results indicate that larvae consume from 160 - 226 cm^2 of leaf area. Estimates of Speyeria population size and Viola leaf area available in the habitat are not currently known. Once these data are obtained, they will be used in conjunction with the amount of leaf area consumed to identify target levels of population size in populations where restoration is needed.