Abstract
ABSTRACT The potential for immigration of female codling moth, Cydia pomonella (L.), to affect the efficacy of control by mating disruption was simulated by incorporating different rates of disruption and immigration into previously published life tables for a univoltine codling moth population on unsprayed apple trees in Nelson, New Zealand. Eight-year simulations were conducted using an initial codling moth density of 1.22 adults per tree at 330 trees per ha, as in the original life tables. Life table simulations without mating disruption served as controls for comparison with simulations that included various rates of disruption, and then various rates of immigration by virgin or mated female moths into trees subjected to 85% or 98% disruption. Model outputs were evaluated principally in relation to a nominal low export tolerance of fresh codling moth damage on harvested fruit of one per million. The simulations suggested that 85% disruption reduced the codling moth population too slowly for such export production, and that this rate of disruption was highly susceptible to immigration of virgin or mated female moths. Mating disruption of 98% provided rapid reduction of codling moth to extremely low population density, even in the presence of virgin female immigration up to ∼30 females per ha. However, although this efficacy should allow export by reducing simulated damage to less than one per million fruit, this was undermined by immigration of mated females as low as ∼0.7 per ha, or one per ∼3500 trees, in modern high-density orchards at 2400 trees per ha.
Published Version
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