Earwigs as biological control agents in temperate tree fruit orchards: what do we know and what is the way forward

Authors: HANEL, ALDO - Washington State Potato Foundation; ORPET, ROBERT - Washington State University; HILTON, RICK - Oregon State University; NOTTINGHAM, LOUIS - Washington State University; Schmidt, Rebecca

Submitted to: Western Orchard Pest and Disease Management Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/29/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: The European earwig can be a pest in cherry and other stone fruit orchards, sometimes requiring the pesticides for control. However, in pear/apple orchards they are a predator of important pests, like aphids and pear psylla. Given this, removing earwigs from stone fruit and releasing them in pears/apples could be a win-win strategy for improving sustainable food production without chemical applications. The goal of this project was to determine if earwig mass trapping in stone fruit could serve as a source of earwigs to increase their population in pears/apples. Researchers at USDA-ARS in Wapato, WA in collaboration with Washington State University and Oregon State University found that rolled cardboard strips captured the most earwigs in stone fruit compared to other trap designs. Mass-trapping earwigs in stone fruit did not significantly reduce their numbers, although there was a subtle trend of reduction over time. There was a reduction in earwig fruit damage on apricots, but not on cherries. Using this strategy, the researchers collected large numbers of earwigs in stone fruit, highlighting the potential of this strategy as a source of earwigs for release in pears/apples. Preliminary results on releasing the captured earwigs did not provide enough evidence to demonstrate that this is a successful method for establishing earwigs in pears/apples. The researchers will continue to collect data examine the viability of this strategy in the long term to improve sustainable tree fruit production

Technical Abstract: The European earwig (Forficula auricularia) is considered a pest in stone fruit orchards, sometimes requiring the use of pesticides to control their populations, whereas in pome fruit orchards they are considered predators of important pests, and infrequently damage fruits. Given this dual role in orchards, our goal was to determine if earwig mass-trapping in stone fruit could serve as a source of earwigs for augmentation biological control in pome fruit. As earwig trapping is infrequent in stone fruit, it is not known if this strategy might reduce their abundance and fruit damage. However, earwigs’ low dispersal and reproductive output may make this strategy successful. We found that the standard cardboard trap was the most successful in capturing earwigs in stone fruit. Mass-trapping of earwigs did not significantly reduce earwig populations, although we noticed a trend of declining populations throughout the season. We observed a decrease in damage on apricots, but not in cherries. Given the large number of earwigs captured in stone fruit, we believe that this strategy might be useful for reducing damage on stone fruit and using it as a “natural biofactory” of natural enemies for augmentation biological control in pome fruit. Preliminary results on earwig augmentation did not provide enough evidence to demonstrate establishment in pome fruit. Studies will continue in the following season to further evaluate mass-trapping as way to reduce earwig populations where they are considered pests and establish their populations in pome fruit