Quality Matters: Influences of Citrus Flush Physicochemical Characteristics on Population Dynamics of the Asian Citrus Psyllid (Hemiptera: Liviidae).

Mamoudou Sétamou,Catherine R Simpson,Olufemi J Alabi,Shad D Nelson,Srilakshmi Telagamsetty,John L Jifon,Leandro Peña

doi:10.1371/journal.pone.0168997

Mamoudou Sétamou, Catherine R Simpson + Show 5 more

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https://doi.org/10.1371/journal.pone.0168997

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Abstract

Studies were conducted to relate the influence of the physical characteristics, leaf nutrient content and phloem sap amino acid concentration of citrus flush shoots on the densities of various Diaphorina citri life stages. Adult D. citri preferentially selected young shoots for feeding and numbers of D. citri immatures were positively correlated with flush shoot softness. Young flush shoots had higher concentrations of macro and micro nutrients relative to mature ones and this was associated with higher densities of all D. citri life stages. All D. citri life stages were positively correlated with higher nitrogen-carbon (N:C), nitrogen:sulfur (N:S) and nitrogen:calcium (N:Ca) ratios in leaf tissue, while densities of adults were negatively related to calcium, manganese and boron levels. Concentrations of total and essential amino acids were highest in phloem sap of young expanding flush shoots in both grapefruit and lemon, but dramatically declined as flush shoots matured. The sulfur-containing amino acids cystine, methionine and taurine occurred only in younger flush shoots. In contrast, cystathionine was only present in phloem sap of mature shoots. These results clearly indicate that young citrus flush shoots are a nutritionally richer diet relative to mature shoots, thus explaining their preference by D. citri for feeding and reproduction. Conversely, tissue hardness and the lower nutritional quality of mature flush shoots may limit oviposition and immature development. The data suggest that both physical characteristics and nutritional composition of flush shoots and their phloem sap are important factors regulating host colonization and behavior of D. citri, and this interaction can impact the dynamics and spread of HLB in citrus groves.

Highlights

The Asian citrus psyllid, Diaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae) is the vector of the phloem-inhabiting bacterial pathogen Candidatus Liberibacter asiaticus (CLas), the primary causal agent of Huanglongbing (HLB) or citrus greening disease in the U.S [1,2,3,4]
No differences were observed in young flush shoot hardness between the two host plants, mature shoots of grapefruit were significantly harder than their lemon counterparts
Calcium is a key component of plant cell walls and thereby plays a vital role in the structural integrity of plant tissues [38,39]

Summary

Introduction

The Asian citrus psyllid, Diaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae) is the vector of the phloem-inhabiting bacterial pathogen Candidatus Liberibacter asiaticus (CLas), the primary causal agent of Huanglongbing (HLB) or citrus greening disease in the U.S [1,2,3,4]. Both ACP and HLB have invaded the U.S during the last decade. In Florida, HLB has caused substantial economic losses totaling more than $4.5 billion from 2006–2012, besides the loss of over 8,000 jobs [8]. And effective control of its vector, D. citri is a key management strategy for reducing the incidence and spread of HLB [9]

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