Plant-herbivorous beetle networks: molecular characterization of trophic ecology within a threatened steppic environment.

Ł. Kajtoch,W. Babik,M. A. Mazur,D. Kubisz,W. Heise

doi:10.1111/mec.13278

Abstract

DNA barcoding facilitates many evolutionary and ecological studies, including the examination of the dietary diversity of herbivores. In this study, we present a survey of ecological associations between herbivorous beetles and host plants from seriously threatened European steppic grasslands. We determined host plants for the majority (65%) of steppic leaf beetles (55 species) and weevils (59) known from central Europe using two barcodes (trnL and rbcL) and two sequencing strategies (Sanger for mono/oligophagous species and Illumina for polyphagous taxa). To better understand the ecological associations between steppic beetles and their host plants, we tested the hypothesis that leaf beetles and weevils differ in food selection as a result of their phylogenetic relations (within genera and between families) and interactions with host plants. We found 224 links between the beetles and the plants. Beetles belonging to seven genera feed on the same or related plants. Their preferences were probably inherited from common ancestors and/or resulted from the host plant's chemistry. Beetles from four genera feed on different plants, possibly reducing intrageneric competition and possibly due to an adaptation to different plant chemical defences. We found significant correlations between the numbers of leaf beetle and weevil species feeding on particular plants for polyphagous taxa, but not for nonpolyphagous beetles. Finally, we found that the previous identifications of host plants based on direct observations are generally concordant with host plant barcoding from insect gut. Our results expand basic knowledge about the trophic relations of steppic beetles and plants and are immediately useful for conservation purposes.

Highlights

The recent development of the concept of barcoding enables examined specimens to be assigned to the appropriate species relatively and quickly (Hebert et al 2003; Moritz & Cicero 2004; Pons et al 2006)
Sampling efficiency Despite the rarity of many steppic beetle species, we managed to collect 55 species of leaf beetles (i.e., 65% of species associated with steppic grasslands in Poland and Central Europe; Borowiec et al 2011; Schmitt & Rönn 2011) and 59 species of weevils (52% of species from Central Europe; Mazur 2001; Wanat & Mokrzycki 2005; see Table 1)
The phylogenetic approach based on rbcL sequences allowed for host plant identification for 62% of leaf beetle species and 65% of weevil species

Summary

Introduction

The recent development of the concept of barcoding enables examined specimens to be assigned to the appropriate species relatively and quickly (Hebert et al 2003; Moritz & Cicero 2004; Pons et al 2006). Previous methods used for the study of herbivores included the direct observation of feeding animals (Sandholm & Price 1962; Dieckmann 1980; Barone 1998; Novotny et al 2002, 2006; Dyer et al 2007) and the analysis of feces (Holechek et al 1982; Johnson & Nicolson 2001) or gut content (Otte & Joern 1976; Fry et al 1978) using morphological or chemical approaches (Dove & Mayes 1996; Dahle et al 1998; Foley et al 1998) All of these methods have serious limitations with regard to their discriminatory power, as they rarely allow for the identification of host plants at the species level.

Objectives

Methods

Results

Conclusion