Growth performance and transcriptomic response of Calliptamus abbreviatus Ikonn (Orthoptera: Acrididae) to suitable and unsuitable host plant species

Abstract

The growth of herbivorous insects is influenced by their host plants, which is underpinned by genetic regulations. We studied the growth performance of the grasshopper Calliptamus abbreviatus Ikonn when it fed on a suitable host plant, Artemisia frigida (Asteraceae) and unsuitable host plant, Stipa krylovii (Poaceae) in a two-year feeding trial. Additionally, the underlying transcriptomic response was also measured using RNA-seq. When C. abbreviatus fed on S. krylovii, it had a significantly reduced growth rate and large variation in its gene expression profiles. A total of 106 genes were significantly up-regulated and mainly enriched in stress resistance-related KEGG pathways. Another 161 genes were significantly down-regulated and were mainly associated with development regulation-, cuticle biosynthesis-, and nutrition metabolism-related pathways. A total of 18 candidate genes were verified by RT-qPCR and were consistent with the transcriptomic results. Stress resistance was significantly induced in grasshopper when C. abbreviatus fed on the unsuitable host. However, the capacity for cuticle biosynthesis or nutrition metabolism significantly declined. The negative effects which S. krylovii had on the grasshopper’s growth performance and gene expression indicate that this plant species was a stressor compared to A. frigida. This study enhances the knowledge on the underlying molecular mechanisms involved in plant–herbivore insect co-evolution.