Advances in RNA suppression of the Asian citrus psyllid vector and bacteria (huanglongbing pathosystem).

The devastation to the US citrus industries from huanglongbing (HLB or citrus greening disease, caused by 'Candidatus Liberibacter asiaticus') is spread during feeding by the Asian citrus psyllid (ACP) Diaphorina citri. Innovative echnologies, such as RNA suppression by RNAi, morpholino oligos, or gene editing tools, including CRISPR/Cas9, all provide non-transgenic strategies, as well as transgenic solutions to manage arthropod vectors, pests and pathogens. Current results from researchers report that these methods enable suppression of ACP vectors, their endosymbionts and the Liberibacter pathogens in infected citrus trees. This chapter reviews several emerging technologies and strategies that enable direct targeting of pathogenic microbes including bacteria in citrus trees, and the critical genes specific to arthropod vectors, such as ACP and their endosymbionts. RNAi-based approaches continue to make advances to improve persistence and activity, especially when applied as an exogenous spray or as soil-applied treatments. RNA-suppressing biopesticides will soon become common in the protection of crops that are either difficult to transform, such as fruit trees, or that are short-term seasonal crops.