Oral delivery of double-stranded RNAs induces mortality in nymphs and adults of the Asian citrus psyllid, Diaphorina citri.

Diogo Manzano Galdeano,Bryce W Falk,João Roberto Spotti Lopes,Marcos Antonio Machado,Michèle Claire Breton,Randall P Niedz

doi:10.1371/journal.pone.0171847

Abstract

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most important citrus pests. ACP is the vector of the phloem-limited bacteria Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, the causal agents of the devastating citrus disease huanglongbing (HLB). The management of HLB is based on the use of healthy young plants, eradication of infected plants and chemical control of the vector. RNA interference (RNAi) has proven to be a promising tool to control pests and explore gene functions. Recently, studies have reported that target mRNA knockdown in many insects can be induced through feeding with double-stranded RNA (dsRNA). In the current study, we targeted the cathepsin D, chitin synthase and inhibitor of apoptosis genes of adult and nymph ACP by feeding artificial diets mixed with dsRNAs and Murraya paniculata leaves placed in dsRNAs solutions, respectively. Adult ACP mortality was positively correlated with the amount of dsRNA used. Both nymphs and adult ACP fed dsRNAs exhibited significantly increased mortality over time compared with that of the controls. Moreover, qRT-PCR analysis confirmed the dsRNA-mediated RNAi effects on target mRNAs. These results showed that RNAi can be a powerful tool for gene function studies in ACP and perhaps for HLB control.

Highlights

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a phloem-feeding insect and the most economically important pest of citrus, mainly because it is the vector for the causal agents of huanglongbing (HLB), Candidatus Liberibacter asiaticus and Candidatus Liberibacter americanus [1,2]
At 120 h post-treatment, inhibitor of apoptosis, cathepsin D and chitin synthase double-stranded RNA (dsRNA) at 500 ng.μL-1 resulted in 51, 47 and 41% ACP mortality, respectively (Fig 1B), and 1000 ng.μL-1 dsRNA produced similar results (64, 52 and 49% mortality, respectively) (Fig 1C). These results demonstrated that inhibitor of apoptosis dsRNAs induced the most potent ACP lethality among the three candidate dsRNAs examined in this study
Present study, we demonstrated the induction of specific RNA interference (RNAi) effects in ACP by oral acquisition of dsRNA from artificial diets and M. paniculata leaves

Summary

Introduction

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a phloem-feeding insect and the most economically important pest of citrus, mainly because it is the vector for the causal agents of huanglongbing (HLB), Candidatus Liberibacter asiaticus and Candidatus Liberibacter americanus [1,2]. HLB occurs throughout the citrus-growing regions of Asia, Africa and the Americas and is the most important disease affecting citrus worldwide, resulting in tree decline, reduced fruit quality and tree death [3,4,5]. A main challenge for researchers has been to develop efficient strategies for D. citri control with low environmental impact, such as the use the ectoparasitoid Tamarixia radiata (Hymenoptera: Eulophidae) [11] as a natural predator [12], entomopathogenic fungi [13] and recently RNA interference (RNAi) [14,15,16]

Methods

Results

Conclusion