The role of spider hunting mode on the strength of spider-plant mutualisms

Author(s)

Kersch-Becker, Monica F. ^{[1, 2]} ; Grisolia, Bruno B. ^[3] ; Campos, Maria J. O. ^[3] ; Romero, Gustavo Q. ^[2]

Affiliation

^[1] Univ Alabama, Dept Biol Sci, Tuscaloosa, AL 35487 - USA

^[2] Univ Campinas UNICAMP, Dept Anim Biol, BR-13083970 Campinas, SP - Brazil

^[3] Univ Sao Paulo UNESP, Dept Ecol, BR-13506900 Rio Claro, SP - Brazil

• Document type: Journal article
• Source: Oecologia; v. 188, n. 1, p. 213-222, SEP 2018.
• Web of Science Citations: 3

Abstract

The strength and outcome of mutualistic interactions can be highly dependent on the combination of traits of the species involved. Distinct foraging strategies (e.g., hunting mode) of mutualistic predators may cause predator-prey interactions to vary, potentially affecting the strength of trophic cascades. We evaluate the causes of variation in the strength of spider-plant mutualisms by focusing on contrasting hunting modes of two spiders: an actively hunting lynx spider (Peucetia sp.) and a sit-and-wait crab spider (Misumenops argenteus). We manipulated spider species composition by assigning each plant to one of the following treatments: (1) no spiders; (2) sit-and-wait spiders only; (3) actively hunting spiders only; (4) actively hunting + sit-and-wait spiders. We then examined the independent and interactive effects of spider species on floral herbivory and fitness of the glandular trichome-bearing plant, Trichogoniopsis adenantha (Asteraceae). Both spider species increased plant fitness by suppressing herbivores and increasing ovary fertilization, but the overall net benefit of spiders was contingent on spider hunting mode. Sit-and-wait spiders promoted stronger positive cascading effects compared to actively hunting spiders. The combination of spider species suppressed herbivores in an additive manner; their combined impact on plant fitness, however, was lower than expected, suggesting that the inter-specific interaction between spiders is slightly antagonistic. Thus, both spider species combined weakened the strength of this spider-plant mutualism. Our findings offer a general framework for understanding the critical role of predator foraging mode in trophic cascades. (AU)

• FAPESP's process: 16/01209-9 - Effects of climate change on the structure of food webs in latitudinal gradients
• Grantee: Gustavo Quevedo Romero
• Support Opportunities: Scholarships abroad - Research