Comparative transcriptomics suggests a highly species-specific nature of the phenotypic plasticity associated with the outbreaks of the two main pest locusts.

Background Locust outbreaks cause devastation and are an important matter for fundamental research. They associate with a striking case of phenotypic plasticity; i.e., a gregarious phase versus solitarious phase polyphenism that affects most aspects of the locusts’ biology. However, changes in behaviour are the most notorious. Changes in gene expression dictate the phenotypic changes, behaviour is key to the locusts’ phase change, and the Central Nervous System (CNS) is essential to behaviour. Therefore, understanding and tackling the phenomenon requires studying the gene expression changes that the locusts’ CNS undergoes between phases. The genes that change expression the same way in different locusts would be ancestrally relevant for the phenomenon in general and those that change expression in a species-specific way would be relevant for species-specific understanding and tackling of the phenomenon. Methods Here, we use available raw sequencing reads to build transcriptomes using the same RNAseq pipeline and to compare the gene expression changes that the CNS of the two main pest locusts ( Schistocerca gregaria and Locusta migratoria ) undergo when they turn gregarious. Our aim is to find out about the species-specificity of the phenomenon, highlight the genes that respond in species-specific manner and those that respond the same way in both species. Results The locust phase change phenomenon seems highly species-specific, very likely due to the inter-specific differences in the biology and life conditions of the locusts. Research on locust outbreaks, gregariousness and swarming should therefore consider each locust species apart—as none seems representative of all locust species. Still, the 109 genes and 39 non-annotated sequences that change expression level the same way in the two main pest locusts provide sufficient material for functional testing in search for important genes, to better understand, or to fight against locust outbreaks. The genes that respond in a species-specific way provide material for understanding the differences between locust species and for looking for potential species-specific weapons against each of them. The still uncharacterized transcripts that change expression either in a species-specific or the same way between the two species provide material for functional testing and gene discovery.