Should I Eat or Should I Go? Acridid Grasshoppers and Their Novel Host Plants: Potential for Biotic Resistance.

Alina Avanesyan

doi:10.3390/plants7040083

Abstract

Novel, non-coevolved associations between introduced plants and native insect herbivores may lead to changes in trophic interactions in native communities, as well as to substantial economic problems. Although some studies in invasion ecology demonstrated that native herbivores can preferentially feed on introduced plants and therefore contribute to the biotic resistance of native communities to plant invasions, the role of acridid grasshoppers as native generalist insect herbivores is largely overlooked. This systematic review aimed to identify patterns of grasshopper feeding preferences for native versus introduced plants and, consequently, a potential of grasshoppers to provide biotic resistance of native communities. The analysis of 63 records of feeding preference trials for 28 North-American grasshopper species (retrieved from 2146 studies published during 1967–2017) has demonstrated a preference of grasshoppers for introduced host plants, and identified 12 preferred introduced plants with high or middle invasive ranks. A significant effect of the life stage (p < 0.001), but not the experimental environment, plant material, and measurements, on grasshopper preferences for introduced plants was also detected. Overall, results suggest a potential of acridid grasshoppers to contribute to the biotic resistance of native communities. The review also provides methodological recommendations for future experimental studies on grasshopper-host plant interactions.

Highlights

Human societies are increasingly moving plant species around the globe: Plants are introduced intentionally for food, landscape restoration, ornamental, and other purposes [1,2], as well as unintentionally, with imported plant material, crop seeds, commercial goods, soil, and by other pathways [1,3,4]
411 studies contained titles and abstracts relevant to insect herbivory, and only 87 studies were conducted on the North-American continent using North-American acridid grasshoppers
It is very encouraging that the number of studies on grasshopper preferences has increased during the last two decades; this corresponds with the general increase of studies on invasion biology [67]

Summary

Introduction

Human societies are increasingly moving plant species around the globe: Plants are introduced intentionally for food, landscape restoration, ornamental, and other purposes [1,2], as well as unintentionally, with imported plant material, crop seeds, commercial goods, soil, and by other pathways [1,3,4]. Some introduced plants escape cultivation and ornamental settings, disperse, and successfully establish in natural ecosystems, becoming potentially invasive (i.e., species causing ecological and economic problems). Out of 25,000 plants introduced in the U.S, an estimated 5000 plant species escaped, invading approximately 700,000 ha of U.S wildlife habitat per year and, in most cases, displacing native plant species [1]. The estimated costs associated with such introduced crop weeds and pasture weeds are $27.9 and $6.0 billion per year, respectively [5]. Substantial economic and environmental problems are caused by some of the introduced (exotic) trees and shrubs, as well as aquatic weeds, which affect the natural habitat of animal species, alter nutrient cycles, and displace native vegetation [1]. A variety of hypotheses have been proposed to explain such successful establishment of exotic plants in the introduced range; Catford et al [6] synthesized 29 hypotheses, which are commonly accepted in studies on plant invasion ecology, that focus on different ecological

Objectives

Methods

Results

Discussion

Conclusion