Johnson, Nia , Puritty, Chandler , McKenna, Mary .
Herbivory Response of Murgantia histrionica to a Ni-hyperaccumulator, Alyssum murale.
Alyssum murale (Brassicaceae) is a nickel-hyperaccumulator native to the Mediterranean region that is generally found on serpentine soils derived from ultramafic rock. Martens and Boyd (1994) proposed the “elemental defense hypothesis,” suggesting heavy metal hyperaccumulation is advantageous in reducing herbivory by insects on plant tissue. Alyssum murale also produces glucosinolates as a chemical defense, in addition to the physical defense of trichomes present on leaves, stems, flowers, and fruits. Murgantia histrionica (harlequin bug) is an aposematic stink bug that primarily feeds on plants in the Brassicaceae (mustard) family. This study explored two questions: Does variation in nickel levels prevent or deter herbivory by Murgantia histrionica on Alyssum murale? and Does Murgantia histrionica show preference for stem vs leaf feeding on A. murale? A. murale seeds were germinated and grown in four soil nickel treatments (0 ppm, 100 ppm, 500 ppm, and 2000 ppm). Soil treatments were prepared using a 1:1 ratio of nickel acetate: nickel sulfate in commercial soil mix. Thirty field-captured M. histrionica individuals were starved 24 hours before each feeding trial. Each trial consisted of releasing one bug into a cardboard feeding arena containing one plant from each soil nickel level. The results showed that stem feeding was preferred to leaf feeding in Murgantia. We found no significant difference in time spent (feeding or not feeding) on plants in all nickel levels, suggesting that Murgantia does not discriminate between feeding on A. murale with and without nickel. This differs from the response we saw in previous studies with the Lepidopteran specialist herbivore, Pieris rapae. Although further research is necessary to evaluate the responses of Murgantia histronica to Alyssum murale throughout its life cycle, these results support work by Boyd (2007) and Jhee et al (2005) indicating that elemental defense may be less effective against piercing-sucking insects compared to leaf chewing folivores.
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1 - Howard University, Biology Department, Washington, DC, 20059, USA
2 - Howard University, Biology Department, Washington, DC 20059 USA
Presentation Type: Poster:Posters for Sections
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Candidate for Awards:Ecological Section Best Graduate Student Poster,Ecological Section Best Undergraduate Presentation Award