Optimizing Spatial Distribution of Pheromone Traps for Monitoring Citrus Leafminer and Related Species

Optimizing Spatial Distribution of Pheromone Traps for Monitoring Citrus Leafminer and Related Species

Report Date: 01/13/2014
Project: 763
Category: ACP Vector
Author: Philip Stansly
Sponsor: Citrus Research and Development Foundation

Citrus leafminer (CLM) is a major pest of citrus, causing direct damage and increased incidence/intensity of citrus canker. Pheromone traps are valuabe for monitoring CLM but need further evaluation to optimize use for management. The objectives of the proposed project include: (1) assess species composition of trap catches, (2) optimize spatial and temporal distribution of pheromone traps. Species composition in trap captures is being evaluated by analysis for Cytochrome Oxidase 1 (CO1) sequence generation incorporating an anchored hybrid enrichment probe set from Illumina HiSeq data with the Lemmon Lab at FSU. The probe set is designed to capture a tiled, 250 bp region of the 658 bp CO1 ‘barcode region’. Blast-searches against the comprehensive BOLD sequence library has allowed a faster, bulk-sequencing approach to the identification of leafminers. Since January 2014, CO1 genes were sequenced from a total of 95 samples of which 65 were recently added to the maximum likelihood phylogenetic analysis. DNA from an additional 70 samples from Silver Strand B9 block, Okaloacoochee Slough State Forest, and Charleston Grove was extracted, analyzed by PCR and is currently being sequenced. Each sample is associated with locality, collection date, type of storage (dry or ethanol), and trap number. Some samples also include morphological data. Two specimens from OK Slough appear in the clade of Phyllocnistis new species 1, and a third appears in the clade of Phyllocnistis new species 2. This is the first time that these two new species have been collected at the Slough. All specimens from the other two localities were citrus leaf miners. Samples collected in 2013-2014 and received in March 2014 are currently being processed, so the current analysis does not include any samples collected during this time frame. Part of the processing will include photography of the specimens prior to extraction. Although many species of Phyllocnistis are cryptic, it is possible that the new species collected in OK Slough can be distinguished from P. citrella by external morphological characters. Photographs of the specimens will help elucidate this in order to provide more accurate identifications. Vince Ficarrotta recently trained David Plotkin in the Kawahara Lab to serve as a part-time assistant through the end of the summer of 2014. David will focus on photographing moths through a microscope and also generate COI sequence data. Almost two years of CLM monitoring for a study to evaluate trap densities and lure efficacy decay under field conditions demonstrated that densities of 1 trap per 2 ha (5 acres) were sufficient to obtain reliable moth counts. Lure efficacy of the two pheromone brands tested declined by 25% after 3-5 weeks and 50% by 6-10 weeks during the spring through fall growing season in Florida. Therefore, large correction factors need to be applied to trap catch readings if traps are replaced at 8-13 weeks. Results obtained will help growers to optimize CLM monitoring programs. A manuscript was submitted to the Journal of Economic Entomology. A formal evaluation of marking techniques was concluded; comparable survivorship of CLM adults powdered or not (P > 0.05) and when exposed to a honey-water solution spiked with blue dye or not (P > 0.05), was demonstrated. Given the shorter period required to affix a mark on CLM with fluorescent powder, this technique will be incorporated. The mark-recapture component is set to begin in April, 2014.


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