Abstract Detail

Ecology

Serpi, Alexandra [1], Dennington, Nina [2], Stephenson, Andrew [3].

The stellate trichomes of Solanum species function in plant defense by damaging the gut lining of an insect herbivore.

Previous studies from our lab have shown that the stellate (non-glandular) trichomes of solanaceous species are not digested as they traverse the guts of Manduca sexta larvae (a common and natural herbivore of solanaceous species), and that the presence of stellate trichomes in the diet decreases larval growth and survivorship. We hypothesized that stellate trichomes function in plant defense by damaging the peritrophic membrane of the larval gut which in turn adversely affects nutrient uptake, necessitates costly membrane repair, and potentially exposes larvae to gut and foodborne microbes and pathogens. To determine if the stellate trichomes of Solanum carolinense damage the gut lining of M. sexta, eggs were collected from an established laboratory colony of M. sexta and raised on artificial diet until the third instar and fifth instar. The third and fifth instar larvae were then randomly separated into two treatments: an artificial diet with fluorescent dye or an artificial diet with trichomes and fluorescent dye. The trichomes were obtained by shaving S. carolinense leaves and adding a realistic concentration of trichomes to the diet (based upon previous feeding studies of larvae on S. carolinense leaves and artificial diet). Larvae were exposed to the treatments for 48 hours and their diet intake, frass, and weight gain were measured. After 48 hours, third instar individuals were placed on a UV transluminator and photographed. Hemolymph was collected from fifth instar individuals and each sample was placed on a UV transluminator and photographed. The larvae consumed significantly less of the diet containing the trichomes and were significantly less efficient at converting the food that was consumed into biomass. The diet with the dye fluoresced in the gut only, but the diet with the dye and the trichomes fluoresced in both the gut and throughout the bodies of the larvae. Moreover, the hemolymph from the 5^th instar larvae that fed on diet with dye and trichomes fluoresced significantly more brightly than the hemolymph from the diet and dye only treatment. These findings suggest that the dye cannot pass through the gut without aid of the trichomes and that trichomes damage the gut lining and thereby hinder larval growth.

1 - Penn State University, Biology, 208 Mueller Lab, University Park, PA, 16802, United States
2 - Penn State University, 208 Mueller Lab, University Park, PA, 16802, United States
3 - Pennsylvania State University, Department Of Biology, 208 Mueller Lab, University Park, PA, 16802, United States

Keywords:
biotic interactions
structure function.

Presentation Type: Oral Paper
Session: ECO1, Ecology 1: Species Interactions
Location: Tucson A/Starr Pass
Date: Monday, July 29th, 2019
Time: 8:45 AM
Number: ECO1002
Abstract ID:95
Candidate for Awards:None