Spatial Distribution and Development of Sequential Sampling Plans for Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Ignacio Sánchez-Cohen,Gabriel Díaz-Padilla,J Isabel López-Arroyo,Rafael A Guajardo-Panes

doi:10.3390/agronomy11071434

Ignacio Sánchez-Cohen, Gabriel Díaz-Padilla + Show 2 more

Open Access

https://doi.org/10.3390/agronomy11071434

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Abstract

Vector control in huanglongbing management has been conducted on a calendar basis resulting in high production costs. We addressed this issue and proposed a sequential sampling plan to support decision making for intervention against Diaphorina citri Kuwayama, which is involved in the transmission of the bacteria Candidatus Liberibacter asiaticus, associated with such lethal disease. We analyzed 3,264,660 records from samples gathered from the Mexican trapping program for the monitoring of D. citri; it included weekly inspection of 86,004 yellow sticky traps distributed in the country. Spatial distribution of the insect, estimation of a common k (kc), and sequential sampling plans based on Sequential Probability Ratio Test (SPRT) were determined. Taylor’s power law coefficients were ≥1 indicating aggregation in the spatial distribution of the insect. Common k ranged from 0.0183 to 0.2253 and varied independently of geographic zone or citrus species. We obtained 18 sequential sampling plans, one for each state. In the Average Sample Number (ASN) function, the minimal number of samples to make a decision ranged from 17 to 65. In the Operational Characteristic (OC) function, probabilities for a correct intervention at the threshold of 0.2 D. citri adults/trap in most cases were above 80%. In a field evaluation, the application of sampling plans yielded savings obtained by reduction in the number of interventions for insect control.

Highlights

Huanglongbing (HLB) is a catastrophic disease of cultivated Citrus trees (Rutaceae)[1,2,3]
When the Asian citrus psyllid (ACP) acquires the bacteria as an adult, the rate of acquisition is low and the time for inoculation is long, both of which result in low infection rates [11]
We evaluated the sequential sampling plans in two diverse citrus groves in Nuevo

Summary

Introduction

Huanglongbing (HLB) is a catastrophic disease of cultivated Citrus trees (Rutaceae)[1,2,3]. There are 66 countries affected in the world, with only the Mediterranean and West Asian citrus producing areas as well as that of Australia and New Zealand, remaining free of the disease [4]. This malady is associated with three forms of a fastidious, phloem limited, and Gram negative α-proteobacterium: Candidatus Liberibacter africanus, Ca. L. americanus, and Ca. L. asiaticus (CLas) [5], with the latter being widely distributed and affecting most of the main major citrus producers worldwide: China, Brazil, India, Mexico, and USA. Individual bacteriliferous ACP adults can transmit CLas at a rate of 4–10%, while groups of 200 adults transmitted the bacterium at a rate of 88% [11]

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