Detecting ingested plant DNA in soil-living insect larvae

Abstract

Although a significant proportion of plant tissue is located in roots and other below-ground parts of plants, little is known on the dietary choices of root-feeding insects. This is caused by a lack of adequate methodology which would allow tracking below-ground trophic interactions between insects and plants. Here, we present a DNA-based approach to examine this relationship. Feeding experiments were established where either wheat (Triticum aestivum) or maize (Zea mays) was fed to Agriotes larvae (Coleoptera: Elateridae), allowing them to digest for up to 72 h. Due to the very small amount of plant tissue ingested (max = 6.76 mg), DNA extraction procedures and the sensitivity of polymerase chain reaction (PCR) had to be optimized. Whole-body DNA extracts of larvae were tested for the presence of both rbcL and trnL plastid DNA using universal primers. Moreover, based on cpDNA sequences encoding chloroplast tRNA for leucine (trnL), specific primers for maize and wheat were developed. With both, general and specific primers, plant DNA was detectable in the guts of Agriotes larvae for up to 72 h post-feeding, the maximum time of digestion in these experiments. No significant effect of time since feeding on plant DNA detection success was observed, except for the specific primers in maize-fed larvae. Here, plant DNA detection was negatively correlated with the duration of digestion. Both, meal size and initial mass of the individual larvae did not affect the rate of larvae testing positive for plant DNA. The outcomes of this study represent a first step towards a specific analysis of the dietary choices of soil-living herbivores to further increase our understanding of animal–plant feeding interactions in the soil.

Tropical Plant–Herbivore Networks: Reconstructing Species Interactions Using DNA Barcodes

“…DNA contamination can be a serious issue with PCR using general plant primers [19]. The most likely cause of this misidentification is DNA contamination as all other samples of C. placida were successfully identified to the correct plant species (Figure 3 B , Supplement S1).…”

The use of DNA barcodes in food web construction—terrestrial and aquatic ecologists unite!

“…Where most molecular studies target single predators or a few species only, a small but growing number of studies have developed molecular tools to resolve smaller and larger modules within food webs, from plant-herbivore interactions (Staudacher et al 2011;Wallinger et al 2012;Garcia-Robledo et al 2013a, 2013bKitson et al 2013;Kajtoch et al 2015) to plant -leaf minerparasitoid networks (Derocles et al 2015). The food webs of soils offer a particular challenge-and particular scope for new insights-as species diversity is relatively high, trophic relations complex, and direct feeding interactions oftentimes impossible to observe.…”

Discriminatory power of rbcL barcode locus for authentication of some of United Arab Emirates (UAE) native plants

“…Some of the applied areas of barcoding are recognizing insect-host relationship (Jurado-Rivera et al 2009), analyzing the diet of herbivores (Valentini et al 2009;Staudacher et al 2011;Stech et al 2011), scrutinizing the components of herbal medicines (Srirama et al 2010), food products (Jaakola et al 2010) and in ecological forensics to identify the plant from a small tissue of root, or seedling or cryptic life stages (e.g., of fern gametophytes) and endangered species.…”