Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/24/2012
Publication Date: 8/24/2012
Citation: Brockerhoff, E., Suckling, D., Kimberley, M., Richardson, B., Coker, G., Gous, S., Cowan, D., Lance, D., Strand, T., Zhang, A. 2012. Mating disruption by aerial application of sex pheromone against the invasive light brown apple moth and implications for the management of biological invasions. PLoS One. DOI: 10.1371/journal.pone.0043767. Interpretive Summary: The light brown apple moth (LBAM) is an economically important invasive pest originally from Australia. It has become established in Hawaii, the U.K., and New Zealand, and invades California in 2007. It attacks many orchards and field crops and damages or kills seedlings of plants. This moth is of particular concern because of its broad host range and ability to survive in a wide variety of climates. Aerial application of insecticides was ruled out in California because much of the treatment area concerned urban and peri-urban areas. In this research, we used synthetic sex attractant to interfere with LBAM mate finding and reproduction, which is recognized as an environmentally friendly method for the management of pest insects. This study involves aerial application by helicopter of four different kinds of attractant formulations as well as hand-applied formulation in New Zealand, where LBAM is highly abundant. The research results demonstrated that aerial application of attractant formulations for mating disruption can be successful as an area wide control or eradication treatment. This finding can help the US regulatory officials, scientists, and growers to understand LBAM mate-finding behavior and develop similar behaviorally based control strategies to manage LBAM population.
Technical Abstract: Biological invasions resulting from international trade can have major ecological and economic impacts. Eradication can be a viable strategy during the early stage of an invasion but there is a need for the development of suitable tactics that are both effective and have minimal non-target effects. Mating disruption is considered to meet these criteria and it was therefore initially chosen as a key tactic for the eradication of light brown apple moth, Epiphyas postvittana (LBAM; Lepidoptera: Tortricidae), in California. The large size of the infested area (eventually defined as ~ 2500 km2) combined with limited accessibility favoured an aerial application approach. Moth sex pheromone formulations were tested in a large scale study in New Zealand where LBAM is highly abundant. Four formulations were applied by helicopter at a rate of 40 g per ha of LBAM pheromone over 5 ha plots (five replicates) in a Pinus radiata forest. Trap catch before and after application was used to assess the comparative efficacy and longevity of formulations, in comparison with plots treated with ground-applied twist-tie pheromone dispensers and untreated control plots. Treatment effects were monitored with traps at 1.5 m and baited with a range of doses of synthetic pheromone or virgin female LBAM. To determine treatment effects higher in the canopy, vertical transects of traps were placed up to 17 m above ground in mature stands. Populations of LBAM were detected in the upper canopy of tall trees, in much higher abundance than at ground level, which has important implications for any program attempting to control LBAM or similar species in rural and urban areas with taller trees. An amorphous wax formulation and twist-ties were able to provide an adequate degree of trap shut-down at ground level for 10 weeks, with other products providing either intermediate or poor control after four weeks. Only the wax formulation was capable of shutting down traps in the upper canopy for up to five weeks. The results demonstrate that aerial application of pheromone formulations for mating disruption can be successful as an area wide control or eradication treatment. All formulations contained at least 15% of Z-11-tetradecen-1-yl acetate, a behavioral antagonist for LBAM, which rendered release points unattractive. This ruled out ‘false trail following’ as a mechanism explaining trap shutdown, indicating that ‘sensory adaptation’ was probably the main mode of operation. The mechanism of mating disruption means it is highly suitable for eradications because it raises the threshold below which population growth becomes negative, leading to extinction.