Mississippi State University
Date of Degree
Graduate Thesis - Open Access
Mass mortality events (MMEs) can affect communities through large amounts of carcass biomass and significant reductions in population sizes. I conducted laboratory experiments to compare effects of predator and herbivore MMEs on a community using a study system of convergent lady beetles (Hippodamia convergens), pea aphids (Acyrthosiphon pisum), and fava beans (Vicia faba). I used a factorial design crossing input (addition of carcasses) and mortality (removing 75% of the population) of aphids and lady beetles. Lady beetle mortality reduced the top-down pressure on the aphid population, which increased aphid abundance and decreased plant height. Input of aphid carcasses increased aphid abundance. Input and mortality of aphids caused the aphid population to diminish suggesting that top-down effects of mortality were more significant than bottom-up effects of carcasses. My results show that MMEs can have effects through both bottom-up and top-down processes, which is dependent upon who experiences the MME.
Hodge, Mariah Ellen, "Functional Identity Mediates the Net Effects of Experimental Mass Mortality Events" (2018). Theses and Dissertations. 2348.