Date of Award

1999

Degree Name

Biology

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Dr. Thomas K. Pauley

Second Advisor

Dr. Leonard J. Deutsch

Abstract

Amphibian declines and deformities are indictors of pollution and other environmental impacts. Pesticides, such as Bacillus thuringiensis var. kurstaki (Bt), may produce non-target effects on salamanders by impacting their food supply, ultimately resulting in population declines. Salamanders were used as an assessment tool of pesticide impacts before populations decline. Diet analysis determined if Bt affected food consumption of two salamander species (Desmognathus ochrophaeus and P. cinereus). Nine plots in the Monongahela National Forest, West Virginia were used in this study. Three plots were sprayed with Bt in 1997 and 1998, three were sprayed with a gypsy moth specific insecticide (Gypchek®) in the same years, and three received no pesticide application. Stomach contents were obtained by hand-collection and stomach pumping specimens in 1997 and 1998. Food items were compared between treatments in 1997 and 1998 separately, and for both years combined. Salamanders were also obtained by pitfall traps from 1995 - 1997. Stomach contents from these samples were compared before and after application of each treatment. There were no differences in diet of either species between treatments after pesticide application in either 1997 or 1998 (Spearman rank correlation, p=0.05). There was no correlation in the diet of either species before and after application of Bt or plots with no pesticide application. There was a correlation of D. ochrophaeus diets from Gypchek plots before and after application. Based on the diets of hand collected salamanders compared between treatments, there is no evidence to show that Bt affects salamander foraging.

Stomach contents, habitat, daily activity and monthly activity determined feeding niche overlaps among six species (D. fuscus, D. monticola, D. ochrophaeus, P. cinereus, P. glutinosus, P. hoffmani). I made 15 pairwise comparisons representing all possible combinations. There are 5 feeding niche overlaps based on food and habitat (Spearman rank, p=0.05). Competition for food may be reduced between P. cinereus and P. glutinosus and between D. fuscus and D monticola by differences in daily activity. Different monthly activity may reduce competition between P. cinereus and P. hoffmani. Desmognathus ochrophaeus is a semi-aquatic species with feeding niche overlaps with both D. fuscus and P. cinereus. Diets from these six species show a continuum of food items from terrestrial to aquatic habitats.

Subject(s)

Salamanders – Feeding and feeds.

Ecology – Effect of pesticides on.

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