title: Is the Combination of Insecticide and Mating Disruption Synergistic or Additive in Lightbrown Apple Moth, Epiphyas postvittana?
abstract: Pest suppression from combinations of tactics is fundamental to pest management and eradication. Interactions may occur among tactical combinations and affect suppression. The best case is synergistic, where suppression from a combination is greater than the sum of effects from single tactics (AB >> A+B). We explored how mating disruption and insecticide interacted at field scale, additively or synergistically. Use of a pheromone delivery formulation (SPLAT™) as either a mating disruption treatment (i.e. a two-component pheromone alone) or as a lure and kill treatment (i.e. the two-component pheromone plus a permethrin insecticide) was compared for efficacy against the lightbrown apple moth Epiphyas postvittana. Next, four point-source densities of the SPLAT™ formulations were compared for communication disruption. Finally, the mating disruption and lure and kill treatments were applied with a broadcast insecticide. Population assessment used virgin female traps and synthetic pheromone in replicated 9-ha vineyard plots compared with untreated controls and insecticide-treated plots, to investigate interactions. Lure and kill and mating disruption provided equivalent suppression; no additional benefit accrued from including permethrin with the pheromone suggesting lack of contact. The highest point-source density tested (625/ha) was most effective. The insect growth regulator methoxyfenoxide applied by broadcast application lowered pest prevalence by 70% for the first ten weeks compared to pre-trial. Pheromone addition suppressed the pest further by an estimated 92.5%, for overall suppression of 97.7% from the treatment combination of insecticide plus mating disruption. This was close to that expected for an additive model of interactivity between insecticide and mating disruption (AB = A+B) estimated from plots with single tactics as 98% suppression in a combination. The results indicate the need to examine other tactical combinations to achieve the potential cost-efficiencies of synergistic interactions.
authors: The New Zealand Institute for Plant & Food Research Limited, Christchurch, New Zealand and School of Biological Sciences, University of Auckland, Building 733, Tamaki Campus, Auckland, New Zealand.|Plant Biosecurity Cooperative Research Centre, Bruce ACT, Australia.|Better Border Biosecurity, Christchurch, New Zealand.
authors: David M
authors: http://orcid.org/0000-0001-7216-9348
authors: DM
authors: Suckling
authors: Plant Biosecurity Cooperative Research Centre, Bruce ACT, Australia.|Entomology Unit, South Australian Research and Development Institute, Adelaide, SA, Australia.
authors: Greg
authors: G
authors: Baker
authors: Plant Biosecurity Cooperative Research Centre, Bruce ACT, Australia.|Entomology Unit, South Australian Research and Development Institute, Adelaide, SA, Australia.
authors: Latif
authors: L
authors: Salehi
authors: Plant Biosecurity Cooperative Research Centre, Bruce ACT, Australia.|Department of Food and Agriculture, South Perth, WA, Australia.
authors: Bill
authors: B
authors: Woods
mesh_terms: D000818:Animals; D007300:Insect Control / Q000379:methods*; D007306:Insecticides / Q000494:pharmacology*; D027845:Malus / Q000469:parasitology*; D009036:Moths / Q000187:drug effects*; D012724:Sex Attractants / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*
chemical_list: D007306:Insecticides; D012724:Sex Attractants