Publications - Faculty - Recently Submitted Faculty Publications 2008
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Stelinski - Entomologia Experimentalis et Applicata
Suppression of citrus leafminer, Phyllocnistis citrella Stainton, with an attracticide formulation
L. L. Stelinski & D. Czokajlo
Abstract: The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a worldwide pest of citrus crops and is responsible for proliferation of citrus bacterial canker, Xanthomonas axonopodis pv. citri. We developed and evaluated an attracticide formulation, termed MalEx, for control of P. citrella. MalEx is a viscous paste with UV-protective properties that is dispensed as 50 μl droplets using custom-made calibrated pumps. A formulation containing 0.016% P. citrella pheromone (3 : 1 blend of (Z,Z,E)-7,11,13-hexadecatrienal and (Z,Z)-7,11-hexadecadienal) and 6% permethrin was found to suppress male response to pheromone in the field superior to formulations containing 10 fold less pheromone. Although formulations without permethrin showed some suppression of male activity due to mating disruption, addition of 6% permethrin was required for optimal efficacy. When MalEx, containing 0.016% pheromone and 6% permethrin, was applied as 3,000 point sources per ha, the height of application did not influence efficacy of male P. citrella suppression within mature 4 m tall citrus trees. Decreasing the rate of MalEx from 3,000 to 1,500 droplets per ha reduced efficacy as measured by both male P. citrella activity and larval infestation. Although 4,500 droplets per ha did not result in statistically better efficacy than 3,000 droplets per ha, there was a noticeable trend for higher efficacy as droplet density was increased. Continuous treatment of 0.5 ha blocks of citrus with MalEx over the course of 112 d reduced larval infestation of new leaf flush by 3.6-7.2 fold, depending on droplet application density. In laboratory behavioral bioassays, we determined that attractiveness of MalEx droplets to male P. citrella was drastically reduced after 21 d of field aging. However, our laboratory investigation confirmed that 100% of males contacting MalEx droplets, aged up to 35 d in the field, were killed within 24 h. Direct observation of male P. citrella behavior in the field confirmed that attracted males made contact with droplets. Control of P. citrella with MalEx should reduce the number of required broad spectrum sprays for leafminer management in both field and citrus nursery settings.
