Spatial distribution of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in citrus orchards

Marilia Gregolin Costa,Pedro Takao Yamamoto,Renata Moreira Leal,José Carlos Barbosa

doi:10.1590/s0103-90162010000500008

Marilia Gregolin Costa, Pedro Takao Yamamoto + Show 2 more

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https://doi.org/10.1590/s0103-90162010000500008

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Journal: Scientia Agricola	Publication Date: Oct 1, 2010
Citations: 48	License type: cc-by

Affiliation: Universidade Estadual Paulista (Unesp)

Abstract

The psyllid Diaphorina citri Kuwayama is one of the most important pests of citrus, mainly because it is the vector of the bacterium that causes huanglongbing (HLB) or 'Greening' disease. To study the spatial distribution of nymphs and adults of this pest, an experiment was carried out in two 'Valencia' sweet orange orchards, four and 12 years of age, established in Matão, central area of São Paulo state, Brazil. The following dispersion indices were used to study pest aggregation in the citrus plants: variance/mean relationship (I), index of Morisita (Iδ), coefficient of Green (Cx), the <img border=0 width=16 height=16 src="../../../../../img/revistas/sa/v67n5/a08form10.gif" align=absmiddle>exponent of negative binomial distribution, common k (<img border=0 width=16 height=16 src="../../../../../img/revistas/sa/v67n5/a08form10.gif" align=absmiddle>c) and Taylor's Power Law for each sampling. The negative binomial distribution was more representative of the spatial distribution of this psyllid, for both nymphs and adults. For most samplings, psyllid nymphs found in branches and adults caught in traps had an aggregated distribution.

Highlights

The psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is currently one of the most important pests of world citriculture. It was discovered in 1907 in Taiwan and is today distributed across several countries of South Asia, regions of the Middle East, the Southern region of the United States, and in Central America, the Caribbean, and South America (Halbert and Manjunath, 2004). This insect has become greatly important because it is the vector of the bacteria that causes huanglongbing, that is restricted to the phloem vessels of plants (Gravena, 2005)
The bacteria Candidatus Liberibacter spp. is transmitted by the psyllid Trioza erytreae (Del Guercio) and D. citri; the first is associated with the African form of the disease (Candidatus Liberibacter africanus), while the second is associated with the Asian (Candidatus Liberibacter asiaticus) (Capoor et al, 1967) and the American forms (Candidatus Liberibacter americanus); the latter is only found in Brazil (ColettaFilho et al, 2004; Teixeira et al, 2005a, b)
Probabilistic models for studying the pest’s spatial distribution - The data of each sampling in each area evaluated were tested to see if they fitted Poisson’s distribution; the hypothesis is that all individuals have the same probability of occupying a given space and the presence of an individual does not affect the presence of another, with variance equal to the mean (σ2 = m) according Barbosa and Perecin (1982); or if they fitted the negative binomial distribution, where the occurrence of an individual limits the occurrence of neighboring individuals in the same unit, with variance higher than the mean (σ2 > m) according to Perecin and Barbosa (1992)

Summary

Introduction

The psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is currently one of the most important pests of world citriculture. Index of Morisita (I ) - it indicates that a distribution is random when it isδ equal to 1, aggregate when it is higher than 1, and regular when it is smaller than 1.

Results

Conclusion