Biological control of vine weevil larvae on protected strawberry

Abstract: In both soft fruit and nursery stock industries, vine weevil (Otiorhynchus sulcatus) remains one of the main pests, causing serious economic problems. Control methods can be targeted against both the larvae which feed on the roots and the adult weevils within the crop which cause leaf notching. Biological control of vine weevil is preferable to the use of insecticides in Integrated Pest Management (IPM) programmes. Current options for biological control of vine weevil larvae include various entomopathogenic nematode species (in the genera Steinernema and Heterorhabditis) and the entomopathogenic fungus Metarhizium anisopliae (Met52). As several nematode products are now commercially available, growers are unsure of which product to use, and how control by nematodes might compare with that given by using Met52 in the substrate. In an experiment in 2013 on a poly-tunnel strawberry crop, Nemasys® L (Steinernema kraussei) was compared with three Heterorhabditis bacteriophora products in a coir substrate, and with Met52 in both coir and peat substrates. Efficacy of Met52 combined with each of the nematode products was also determined in coir. All the nematode products and Met52 significantly reduced the numbers of live vine weevil larvae in the coir substrate when compared with untreated controls. Combining nematodes with Met52 in the coir substrate did not significantly improve the control of vine weevil larvae compared with using nematodes alone.