Development on Infected Citrus over Generations Increases Vector Infection by 'Candidatus Liberibacter Asiaticus in Diaphorina citri'.

Inaiara De Souza Pacheco,João Roberto Spotti Lopes,Marcos Antonio Machado,Diogo Manzano Galdeano

doi:10.3390/insects11080469

Inaiara De Souza Pacheco, João Roberto Spotti Lopes + Show 2 more

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https://doi.org/10.3390/insects11080469

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Abstract

‘Candidatus Liberibacter asiaticus’ (CLas) is a major causal agent of citrus Huanglongbing (HLB), which is transmitted by Asian citrus psyllid (ACP), Diaphorina citri, causing severe losses in various regions of the world. Vector efficiency is higher when acquisition occurs by ACP immature stages and over longer feeding periods. In this context, our goal was to evaluate the progression of CLas population and infection rate over four ACP generations that continuously developed on infected citrus plants. We showed that the frequency of CLas-positive adult samples increased from 42% in the parental generation to 100% in the fourth generation developing on CLas-infected citrus. The bacterial population in the vector also increased over generations. This information reinforces the importance of HLB management strategies, such as vector control and eradication of diseased citrus trees, to avoid the development of CLas-infected ACP generations with higher bacterial loads and, likely, a higher probability of spreading the pathogen in citrus orchards.

Highlights

Huanglongbing disease is the most destructive bacteriosis in the citrus industry around the world
Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the natural vector of ‘Candidatus Liberibacter asiaticus’ (CLas), the main bacterium associated with HLB across citrus crops of the Americas and Asia
It was observed that the proportion of CLas-infected ACPs and the bacterial load both increase when ACPs are reared on CLas-infected plants over several generations

Summary

Introduction

Huanglongbing disease is the most destructive bacteriosis in the citrus industry around the world This disease is characterized by yellow and mottled shoots, with leaves presenting chlorotic spots similar to nutritional deficiencies. ACP transmits CLas in a circulative-propagative manner, which involves pathogen acquisition during phloem-sap ingestion, movement and multiplication in vector organs, followed by inoculation via saliva [2,3,4]. Both ACP nymphs and adults can acquire CLas, but this pathogen multiplies faster, reaches higher populations and is more efficiently transmitted in psyllids that acquire it during immature stages [5,6]

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