Search for: All records

Predators impact prey populations directly through consumption and indirectly via trait-mediated effects like predator-induced emigration (PIE), where prey alter movement due to predation risk. While PIE can significantly influence prey dynamics, its combined effect with direct predation in fragmented habitats is underexplored. Habitat fragmentation reduces viable habitats and isolates populations, necessitating an understanding of these interactions for conservation. In this paper, we present a reaction–diffusion model to investigate prey persistence under both direct predation and PIE in fragmented landscapes. The model considers prey growing logistically within a bounded habitat patch surrounded by a hostile matrix. Prey move via unbiased random walks internally but exhibit biased movement at habitat boundaries influenced by predation risk. Predators are assumed constant, operating on a different timescale. We examine three predation functional responses—constant yield, Holling Type I, and Holling Type III—and three emigration patterns: density-independent, positive density-dependent, and negative density-dependent emigration. Using the method of sub- and supersolutions, we establish conditions for the existence and multiplicity of positive steady-state solutions. Numerical simulations in one-dimensional habitats further elucidate the structure of these solutions. Our findings demonstrate that the interplay between direct predation and PIE crucially affects prey persistence in fragmented habitats. Depending on the functional response and emigration pattern, PIE can either mitigate or amplify the impact of direct predation. This underscores the importance of incorporating both direct and indirect predation effects in ecological models to better predict species dynamics and inform conservation strategies in fragmented landscapes. 

Abstract Black flies (Diptera: Simuliidae) are reemerging as biting and nuisance pests in many southern states, presumably from improving water quality in creeks and rivers. Since 2009, entomologists at Mississippi State University and the Mississippi Department of Health have conducted surveys to ascertain what black fly species are present in the state as well as their geographic distribution and seasonality. These surveys revealed what appears to be a recurring, significant emergence of black flies every year around 25 December at one site in southern Mississippi. In this study, adult black flies were collected from 1 January 2018 to 31 December 2021 by hand netting in the exact same way each time at Okatoma Creek, Seminary, MS. Forty-eight collecting trips to the site over the 4-yr period yielded a total of 176 black flies, all morphologically identified as Simulium jenningsi Group Malloch. Molecular identification was successfully performed on 17 specimens collected during the December outbreaks. Of the 17 specimens analyzed, 10 and 7 specimens grouped with 100% bootstrap confidence inside clades comprising S. jenningsi or S. podostemi, respectively.