Abstract
Biological invasions can cause major ecological and economic impacts. During the early stages of invasions, eradication is desirable but tactics are lacking that are both effective and have minimal non-target effects. Mating disruption, which may meet these criteria, was initially chosen to respond to the incursion of light brown apple moth, Epiphyas postvittana (LBAM; Lepidoptera: Tortricidae), in California. The large size and limited accessibility of the infested area favored aerial application. Moth sex pheromone formulations for potential use in California or elsewhere were tested in a pine forest in New Zealand where LBAM is abundant. Formulations were applied by helicopter at a target rate of 40 g pheromone per ha. Trap catch before and after application was used to assess the efficacy and longevity of formulations, in comparison with plots treated with ground-applied pheromone dispensers and untreated control plots. Traps placed at different heights showed LBAM was abundant in the upper canopy of tall trees, which complicates control attempts. A wax formulation and polyethylene dispensers were most effective and provided trap shut-down near ground level for 10 weeks. Only the wax formulation was effective in the upper canopy. As the pheromone blend contained a behavioral antagonist for LBAM, ‘false trail following’ could be ruled out as a mechanism explaining trap shutdown. Therefore, ‘sensory impairment’ and ‘masking of females’ are the main modes of operation. Mating disruption enhances Allee effects which contribute to negative growth of small populations and, therefore, it is highly suitable for area-wide control and eradication of biological invaders.
Highlights
Biological invasions resulting from trade and other human activities represent a major threat to biodiversity and the integrity of ecosystems [1]
The results are presented in four section addressing (1) mating disruption treatment effects near ground level and relationships with pheromone release characteristics of formulations, (2) effects of horizontal trap position, (3) distribution of catches in vertical transects across the canopy, and (4) mating disruption effects at different heights across the canopy
Over 28,700 male LBAM were trapped during this trial, of which over 25,000 catches occurred near ground level where mating disruption is usually assessed, and where the majority of our traps were located
Summary
Biological invasions resulting from trade and other human activities represent a major threat to biodiversity and the integrity of ecosystems [1]. MD by aerial application of moth pheromones has been widely used in the U.S for the gypsy moth, Lymantria dispar, ‘‘slow-the-spread’’ program; up to 2008 more than 1.4 million ha were treated with MD formulations [10] This is considered environmentally friendly and more cost-effective than alternatives for suppressing gypsy moth populations [18]. Biological control and IPM programs, using insecticides and other methods, contribute to successful management in New Zealand, LBAM remains very abundant in organic orchards [21] and pine forests [22]. We report the results of a substantial study involving aerial application by helicopter of four different pheromone formulations as well as hand-applied pheromone polyethylene tubing dispensers (hereafter referred to as ‘twist-ties’) in New Zealand, in a pine forest with abundant LBAM [22]. This study is important for the response to the incursion of LBAM in California and for similar uses against other species where ‘greener’ yet effective alternative incursion response and management methods are required
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