Identification of the role of earwigs in blackcurrant plantations

Summary: Research at EMR has shown that pear and apple orchards vary enormously in the numbers of common European earwigs (Forficula auricularia) that reside in them. Indeed, some orchards appear to have no earwigs at all. The reasons for this are not certain, but the use of some insecticides may be playing a role. As part of the Blackcurrant HortLINK project it was observed that although there were reasonable numbers of blackcurrant sawfly adults being captured in the newly developed pheromone traps and eggs and young larvae were sometimes found on young leaves in the centre of the bush, larvae and significant leaf damage was not always occurring. The current AHDB Blackcurrant sawfly project, SF 162, aims to optimise the sawfly pheromone trap with spray thresholds and some estimation of earwig numbers. However earwigs may be playing a more significant role in pest control in blackcurrants. In apple and pear, these nocturnal predators have been shown to have significant effects on aphid numbers and also feed on other pests such as scale insects, caterpillars and midge larvae.

It is not known how abundant earwigs are in UK blackcurrant plantations, whether they are impacted by plant protection products or what role they play in pest control on this crop.