Radio-tagging earwigs to understand the breakdown in successful woolly apple aphid, Eriosoma lanigerum (Hausmann) control

The woolly apple aphid, Eriosoma lanigerum (Hausmann) (WAA), is becoming an increasingly important pest in apple orchards. Damage from the aphids and their waxy residue can become severe reaching the shoot tips and contaminating the fruits. Reasons for the increased occurance of WAA are not entirely clear and could include changes in pesticide use, climate change and rootstock resistance breakdown. However, the common European earwig, Forficula auricularia L. (Dermaptera), is known to be an important predator of WAA. Studies in the Netherlands have suggested that 8 earwigs foraging in a tree at night could be enough to reduce WAA incidence. Pilot data collected in a NIAB EMR Innovate study showed that earwigs in refuges tied into trees were not evenly distributed between trees in the orchards. In addition no direct relationship between earwig and WAA distribution in UK apple orchards has been established. Earwigs also play a key role in regulating populations of other aphid pests, mussel scale, codling moth and pear sucker. Because earwigs are nocturnal they represent a challenging insect to study. Studies at Harper Adams University demonstrated the use of passive radio frequency identification (RIFD) tags to trace the activity of vine weevil in crops. Smaller RFID tags are used in honey bee and bumblebee research, where the reader can be positioned at the entrance of the nest. As earwigs readily use artificial shelters placed within tree canopies tiny RFID tags could enable earwig behaviour to be monitored in the field allowing the relationship of earwig foraging and WAA populations to be studied. This will inform growers whether the diistribution of earwigs in orchards has an impact on WAA populations and help mitigate WAA incidence in orchards.
Aims
The overall aim is to develop a greater understanding of earwig migration in orchards and foraging behaviour in relation to WAA populations and to use this knowlegde to develop methods to mitigate WAA build-up. This PhD will train the student in several aspects of insect behaviour, including developing novel RFID techniques and give the student an understanding of orchard agronomy and IPM.
Objective 1. Map WAA populations in relationship to earwig foraging in apple orchards
Objective 2. Adapt an insect RFID system and refuge to track earwig behaviour in relation to WAA
Objective 3. Determine the movement (migration) and foraging behaviour of earwigs (lab and field experiments) in relation to WAA colonies in apple trees
Objective 4. Test the mitigation of WAA build-up by deploying refuges preloaded with earwigs into WAA infested trees
Objective 5. Develop guidance for fruit growers on the prevention of WAA by exploiting earwig