Abstract Detail

Ecology

Schulz, Ashley [1], Lucardi, Rima [2], Marsico, Travis [3].

The Forgotten Fourth Trophic Level: Natural Enemies Influence the Success or Failure of Non-Native Invaders and Biological Control Agents .

Understanding the role of natural enemies in the success and failure of invasive species is a fundamental challenge for biological invasion and biological control scientists, with increasing focus in these areas since the 1980s. Almost too many hypotheses have been proposed in an effort to explain the dynamic relationships between invading species and their natural enemies, those from their native range, as well as generalist and specialist enemies that are encountered in the introduced range. We identified ten, key hypotheses addressing the role of enemies in understanding biological invasion: biotic resistance, enemy inversion, enemy of my enemy, enemy reduction, enemy release, enemy resistance, enemy tolerance, evolution of increased competitive ability (EICA), new associations, and resource-enemy release hypotheses. We suggest the enemy release hypothesis may serve as an overarching hypothesis that branches into the other, more specific sub-hypotheses. Of these sub-hypotheses, the enemy inversion hypothesis is the only to address the vulnerability of biological control agents –organisms anthropogenically and purposefully introduced to control invasive species – to enemies from their native and introduced ranges. Records of intentionally or inadvertently non-native hyperparasitoids, and other enemies of typical insect biological control agents, are few. Furthermore, little research has experimentally evaluated the role of these fourth trophic level enemies on the success or failure of biological control agents, and the feedbacks, positive or negative, on invading species. We suggest additional effort devoted to studies that: 1) synthesize and unify the many hypotheses in invasion ecology, including “enemy” hypotheses, 2) consider the role of multiple, concurrent mechanisms (i.e., top-down, bottom-up, competition, etc.) in the establishment and success of invading species, and 3) experimentally expand enemy hypotheses to assess role(s) and impacts(s) of the fourth trophic-level enemies in biological control success and failure impacting the success or failure of invasive species in natural ecosystems.

1 - Arkansas State University, Department of Biological Sciences, PO Box 599, State University, AR, 72467, USA
2 - USDA Forest Service - Southern Research Station, 320 Green Street, Athens, GA, 30602, United States
3 - Arkansas State University, Department Of Biological Sciences, PO Box 599, State University, AR, 72467, USA

Keywords:
biological control
enemy release
fourth trophic level
invasive species
natural enemies.

Presentation Type: Oral Paper
Session: 8, Ecology Section - Invasive Species
Location: Sundance 5/Omni Hotel
Date: Monday, June 26th, 2017
Time: 11:15 AM
Number: 8005
Abstract ID:135
Candidate for Awards:Ecological Section Best Graduate Student Paper