Net enclosures disrupt codling moth dispersal not establishment

Abstract

1. Apple growers have pursued the use of exclusion netting to reduce pesticide inputs and maintain control of codling moth.2. It is uncertain if these nets provide a physical or behavioural behaviour, and if they prevent codling moth establishment.3. To address this, we conducted field trials testing the ability of commercial netting to exclude codling moth using small (3 trees) and large (48 trees) cages. Experiments were conducted to evaluate both the permeability by releasing marked sterile moths either inside or outside the small cages, and the establishment of wild codling moth in the large cages.4. Results from the small cage study showed that netting reduced codling moth movement out of the netted plots, but virtually prevented codling moth dispersal into the plots. Codling moth capture inside the large cage plots was significantly less than in uncaged plots, but no differences were found in codling moth damage at harvest. 5. These results indicate that the netting is physically permeable to codling moth adults; however, it acts as a behavioural barrier to moth immigration. These outcomes agree with existing literature that net enclosures can provide a noninsecticidal tool to improve codling moth management, although it may not be a stand-alone technique.

Hail netting: an economically competitive IPM alternative to insecticides for Midwest apple production

“…Netting studies published thus far for apple fruit have focused on insect pest exclusion benefits in Europe ( 20 , 22 , 23 ) and North America ( 17 , 19 , 24 , 31 ). However, as noted by Onstad and Crain ( 62 ) and Fornasiero et al.…”

“…Previous studies have documented that both the apple maggot and codling moth are able to move through mesh sizes that are similar to those employed in hail netting ( 28 , 30 , 31 ). However, it is believed that the presence of netting interrupts mate-seeking behavior in the codling moth ( 22 , 31 ).…”

“…Previous studies have documented that both the apple maggot and codling moth are able to move through mesh sizes that are similar to those employed in hail netting ( 28 , 30 , 31 ). However, it is believed that the presence of netting interrupts mate-seeking behavior in the codling moth ( 22 , 31 ). Similarly, netting may interrupt host-seeking behavior in apple maggot since they seek out trees and fruit primarily using visual and olfactory cues, but this has not been documented in the field ( 32 – 34 ).…”

Hail netting excludes key insect pests and protects from fruit damage in a commercial Minnesota apple orchard

“…More recently, a study in Washington found that codling moth could be excluded by using net cages (2 × 5 mm mesh) placed around large orchard blocks ( Marshall and Beers 2021 , 2022 ). While successful at reducing fruit injury initially, these cages did allow a few individuals through, and over time moths were able to establish a population within these blocks ( Marshall and Beers, 2023 ). Additionally, the investigators found that while the cages effectively excluded large, flying insects, smaller and less mobile insects such as aphids were consistently more abundant inside cages than outside ( Marshall and Beers 2021 , 2022 ).…”

“…Both the apple maggot and codling moth are able to move through mesh sizes that are similar to those employed in hail netting (variable mesh size: 7.4 × 3 mm, 6 × 1.8 mm, etc.) ( Sauphanor et al 2012 , Chouinard et al 2022 , Marshall and Beers 2023 ). It is believed that effective exclusion is due to both small mesh sizes and interference with mate-seeking behavior in the codling moth ( Tasin et al 2008 , Marshall and Beers 2023 ).…”