Title: Intentional coverage gaps reduce cost of mating disruption for the leafminer Phyllocnistis citrella in citrus Authors
|Stelinski, L -|
|Mafra Neto, A -|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2014
Publication Date: N/A
Interpretive Summary: The citrus leafminer has become a major pest of citrus throughout Florida. The leafminer causes direct damage by feeding and facilitates the entry of citrus canker disease into leaves through wounds caused by the caterpillar. SPLAT CLM is a wax matrix used to deliver the sex pheromone of the citrus leafminer to citrus trees in commercial orchards to disrupt the ability of male leafminers to locate females and thereby reduce their numbers while avoiding the use of broad-spectrum insecticides. The cost of producing the sex pheromone through chemical synthesis is significant and motivated a set of studies to determine if effective control could be accomplished by applying SPLAT CLM with intentional coverage gaps (skipped rows). Field experiments demonstrated that a coverage pattern of 4 skipped and 10 treated rows resulted in a 29% savings in SPLAT CLM while reducing trap shutdown (a measure of mating disruption) by only 4%. The number of active mines in citrus shoots of trees treated with SPLAT CLM was reduced by 53% compared with untreated trees. The results of these studies should contribute to the adoption of this environmentally appropriate method of control of a major citrus pest and disease.
Technical Abstract: The leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a global pest of citrus and contributes to the incidence and severity of citrus bacterial canker, Xanthomonas axonopodis pv. citri. SPLAT-CLM™ (ISCA Technologies)is an emulsified wax product that provides sustained release of (Z,Z,E)-7,11,13-hexadecatrienal, the major component of the P. citrella sex pheromone. Field trials demonstrated that SPLAT CLM applied to plots of varying width (number of rows of citrus trees in commercial groves) resulted in disruption of trap catch of male P. citrella within the treated area and across an untreated set of rows adjacent to the treated rows. Applications of SPLAT CLM to plots of constant width (10 rows) disrupted trap catch across an untreated gap as the square of the width of the gap. Similarly, the ability of the pheromone source in treated rows to disrupt trap catch across an untreated gap of constant size declined as the square of the width of the adjacent treated area. A coverage pattern of four skipped rows for every 10 treated rows, equal to an approximately 29% reduction in product and application costs, resulted in an approximate 4% loss of trap shutdown, an indirect measure of mating disruption. These results suggest that the cost of mating disruption can be significantly reduced through the use of appropriate coverage patterns. Commercial lures for P. citrella used in this study were highly potent with respect to attracting males. Each lure was approximately 103 times as attractive as an individual P. citrella female. Disruption of trap catch using such commercial lures may underestimate the actual degree of mating disruption achieved in the field.