Theses and Dissertations

EFFECT OF DISTURBANCE (MOWING) ON FLORIVORY AND HERBIVORE DEFENSES IN SOLANUM ELAEAGNIFOLIUM FOCUSED ON THE IMPACT OF AN ANTHROPOGENIC DISTURBANCE, MOWING, ON A NOXIOUS, HIGHLY DAMAGING WEED

Alejandro Rafael Vasquez Marcano, The University of Texas Rio Grande Valley

Copyright 2023 The Author. All Rights Reserved.

Abstract

To further investigate the effect of an anthropogenic disturbance, mowing, on floral fitness and defense traits, we used a combination of field studies and lab experiments with 6 mowed and 6 unmowed sub populations of Solanum elaeagnifolium, Silverleaf Nightshade (SLN), to ask the following questions: (1) Does mowing influence floral fitness and defense traits, (2) How does mowing affect field herbivory on floral parts (petals and anthers) on a damage scale, (3) How do mowed and unmowed plants affect herbivore (Manduca sexta) mass when the plant material is added to artificial Lepidoptera diet, and (4) Are these effects, if any, affected by the frequency of mowing undergone by the SLN populations at different times of the year? We hypothesized that because of continuous mowing disturbance, mowed plants will exhibit lower floral fitness traits than unmowed plants, yet their defense traits and effect on herbivores will be more pronounced as an overcompensation adaptation to consistent stress in line with how plants response to stress induced by mechanical wounding and defense signaling. To answer herbivory questions, we utilized Tobacco hornworm (Manduca sexta), a generalist on Solanaceae. We also hypothesized that a higher frequency of mowing would compromise fitness and defense floral traits.