Probing behaviors and their plasticity for the aphid Sitobion avenae on three alternative host plants

Hemocyanin contributes to embryonic adaptation to hypoxia in the migratory locust

Ambient hypoxia can pose a major threat to the survival of metazoan organisms, especially insect embryos. Hemocyanin exhibits dominant expression in insect embryos, but its specific roles in hypoxia adaptation remain unexplored. Soil-dwelling locust eggs may frequently experience hypoxia during development. A comprehensive analysis of physiological and biochemical characters of hemocyanin was conducted in the embryos of migratory locust Locusta migratoria. Our results demonstrated that the revolution process was the critical hypoxia-sensitive event during locust embryogenesis. Hemocyanin presented a prominent expression in the revolution stage and exhibited strong responses to hypoxia. The relative duration of revolution was correlated negatively with the expression of hemocyanin subunit 2 (HC2), suggesting that HC2 might be closely associated with hypoxia adaptation of locust embryos. Furthermore, a HC2 mutant locust strain was established using the CRISPR/Cas9 technology, and higher hypoxia sensitivity was found for HC2-deficient locust embryos. Knockdown of HC2 increased anaerobic metabolism and oxidative stress while reducing oxidative metabolism. Overall, these findings clearly demonstrated the pivotal roles of hemocyanin in hypoxia adaptation of insect embryos.

A neural m6A pathway regulates behavioral aggregation in migratory locusts

RNA N6-methyladenosine (m6A), as the most abundant modification of messenger RNA, can modulate insect behaviors, but its specific roles in aggregation behaviors remain unexplored. Here, we conducted a comprehensive molecular and physiological characterization of the individual components of the methyltransferase and demethylase in the migratory locust Locusta migratoria. Our results demonstrated that METTL3, METTL14 and ALKBH5 were dominantly expressed in the brain and exhibited remarkable responses to crowding or isolation. The individual knockdown of methyltransferases (i.e., METTL3 and METTL14) promoted locust movement and conspecific attraction, whereas ALKBH5 knockdown induced a behavioral shift toward the solitary phase. Furthermore, global transcriptome profiles revealed that m6A modification could regulate the orchestration of gene expression to fine tune the behavioral aggregation of locusts. In summary, our in vivo characterization of the m6A functions in migratory locusts clearly demonstrated the crucial roles of the m6A pathway in effectively modulating aggregation behaviors.

Genetic diversity in vector populations influences the transmission efficiency of an important plant virus

The transmission efficiency of aphid-vectored plant viruses can differ between aphid populations. Intra-species diversity (genetic variation, endosymbionts) is a key determinant of aphid phenotype; however, the extent to which intra-species diversity contributes towards variation in virus transmission efficiency is unclear. Here, we use multiple populations of two key aphid species that vector barley yellow dwarf virus (BYDV) strain PAV (BYDV-PAV), the grain aphid (Sitobion avenae) and the bird cherry-oat aphid (Rhopalosiphum padi), and examine how diversity in vector populations influences virus transmission efficiency. We use Illumina sequencing to characterize genetic and endosymbiont variation in multiple Si. avenae and Rh. padi populations and conduct BYDV-PAV transmission experiments to identify links between intra-species diversity in the vector and virus transmission efficiency. We observe limited variation in the transmission efficiency of Si. avenae, with transmission efficiency consistently low for this species. However, for Rh. padi, we observe a range of transmission efficiencies and show that BYDV transmission efficiency is influenced by genetic diversity within the vector, identifying 542 single nucleotide polymorphisms that potentially contribute towards variable transmission efficiency in Rh. padi. Our results represent an important advancement in our understanding of the relationship between genetic diversity, vector-virus interactions, and virus transmission efficiency.