Bioenergy Crops and Natural Enemies: Host Plant-Mediated Effects of Miscanthus on the Aphid Parasitoid Lysiphlebus testaceipes

Abstract

Miscanthus spp. are biofuel crops that are triggering growing interest worldwide due to their numerous agronomic advantages. Though breeding programs take into account usual key plant traits of agronomic interest (e.g., biomass production, adaptation to broader climatic range), they generally overlook plant attributes relating to pest and pathogen resistance and even more those that may favor or improve the combined use of biological control agents of pests. A recent study showed that the parental species, Miscanthus sacchariflorus and, to a lesser extent, Miscanthus sinensis, were less suitable and acceptable host plants for the corn leaf aphid Rhopalosiphum maidis, one of the main pests of Miscanthus × giganteus in the USA, than the hybrid M. × giganteus. In the present laboratory study, we investigated the host plant-mediated effects of these three miscanthus species on various life history traits of the aphid parasitoid Lysiphlebus testaceipes. A clear host plant effect was shown on aphid size and, consequently, on parasitoid fitness parameters. High plant resistance to aphids was shown to be more detrimental to the parasitoid than partial resistance, with M. sacchariflorus being the least suitable host plant to both aphid and parasitoid development. Selection of partial resistance, such as the one exhibited by M. sinensis, should then be preferred to support efficient aphid regulation by parasitoids. This study provides the first contribution to the evaluation of bottom-up effects of a biofuel crop on beneficial insects. It also underlines the need to conduct additional research when considering the implementation of new biomass crops.

Aphid Parasitoid Mothers Don't Always Know Best through the Whole Host Selection Process

“…e ., mated, fed, and without oviposition experience) with a single three-day-old A . fabae nymph in a small Eppendorf tube (0.5 ml), as described in [ 35 ]. Each parasitoid female was only used once.…”

How the use of nitrogen fertiliser may switch plant suitability for aphids: the case of Miscanthus, a promising biomass crop, and the aphid pest Rhopalosiphum maidis

“…Indeed, some studies using in vitro plants have pointed out that M. sacchariflorus shows a greater resistance to the corn leaf aphid R. maidis than M. sinensis and M . × giganteus . Another study using potted plants has shown that M. sinensis is more resistant than M .…”

“…20 Indeed, some studies using in vitro plants have pointed out that M. sacchariflorus shows a greater resistance to the corn leaf aphid R. maidis than M. sinensis and M. × giganteus. 21,22 Another study using potted plants has shown that M. sinensis is more resistant than M. × giganteus, raising the possibility that M. sinensis could represent a better alternative to M. × giganteus under heavy aphid pressure. 20 These studies suggest that Miscanthus breeding programmes should also take into account traits that are related to resistance to insect pests.…”