Development And Growth Of Clostera Anachoreta Mediated By Ectomycorrhizal Fungus Paxillus Involutus Inoculated On Populus × Canescens

The roots of most land vascular plants can form a symbiotic association(mycorrhiza) with special fungi. The symbiosis affects performance of above-ground insect herbivores by enhancing availability of nutrients, or modifying concentration of defense compounds in the host plant. Owing to more concerns about genetically modified organisms and problems with pesticides in the landscape: resurgence, residue and resistance, we have focused on mycorrhized breeding to prevent forest insect pests more efficiently and eco-friendly.In this study, the development of Clostera anachoreta Fabricius was explored when 1st instar larvae fed poplar foliage from seedlings either inoculated with ectomycorrhiza Paxillus involutus for eight months or the non-inoculated counterpart. Our results indicated that the larval weight(2nd and 3rd instar) and head capsule width were significantly reduced and the larval period was obviously prolonged by feeding on ectomycorrhizal infected poplar leaves. However, the development of pupae(i.e. pupal weight and pupal period) and the adults(i.e. adult weight, oviposition and longevity) were little influenced by the ectomycorrizal fungus inoculation in the host plant. Naturally, to investigate the underlying physiological mechanisms, differences were observed in the concentration of total nitrogen, phosphorus, soluble sugar, proteins, starch, soluble phenolics and hormones of mycorrhizal and control populus. The results illustrated that the mineral nutrition(i.e. total nitrogen and phosphorus), soluble proteins and starch remained steady after inoculation with the ectomycorrhiza, whereas the soluble sugar, which is closely bound up with the growth of leaf-chewing caterpillars, declined dramatically in ectomycorrhizal seedlings. In addition, the concentration of jasmonic acid and salicylic acid revolved in plant systemic acquired resistance soared up in the effect of ectomycorrhiza Paxillus involutus, likewise, the soluble phenolics increased but much less significantly.By and large, ectomycorrhiza Paxillus involutus apparently inhibited the development of lower instar larvae of Clostera anachoreta by altering the nutrition allocation and priming systemic defense responses in the host plant. According to the slow-growth-high-mortality hypothesis, application of Paxillus involutus rendered Clostera anachoreta larvae more susceptible to natural enemies. Furthermore, the point is also valid in bio-control of forest insect pests. Besides, we uncovered the defense responses in Populus × canescens upon herbivores attack induced by mycorrhizal colonization through the determination of nutrients and defensive secondary metabolites associated with insect growth. Thus, the present study lays an experimental foundation and provides a reference for controlling pests with utilization of ectomycorrhiza.