Replacing Pesticides with Fungi

Reducing pesticide use has been a major EU policy goal over the last few years. One way the EU intends to achieve this is by developing biological or non-chemical pesticides as replacements for conventional pesticides. Now, a new UK study has delivered some promising suggestions as to how this may be done.

The study identified some naturally occurring alternatives to control wireworm, a pest which causes major problems in arable crops in many parts of the world. Wireworms are the larvae of click beetles, and they have a particularly harmful impact on potato yields (when more than 10-15 per cent of potatoes are damaged, the crop is no longer financially viable for the farmer).

Normally wireworms are controlled by applying insecticides to the soil. The study however identified three alternative, naturally occurring, pesticides that showed promise for development. These were two types of parasitic fungi and one type of parasitic nematode (or roundworm).

The researchers investigated the pesticidal properties of six fungi and twelve nematodes in all. The wireworms were exposed to the different parasites and the mortality of the wireworms was assessed every week for three weeks. The dead larvae were dissected to confirm the cause of death. After three weeks, there were significant differences in the effects of the fungi. Most striking were the effects of the Metarhizium anisopliae strains, V1002 and LRC181A, which caused 90-100 per cent mortality. There were also significant differences in the parasitic effects of the different types of nematode. The most aggressive was the UK strain of Heterorhabditis bacteriophora, UWS1, that caused 67 per cent mortality.

Previous research has demonstrated that the fungi M. anisopliae can work together with chemical pesticides to control wireworm and other pests, and the fungi could therefore be used to reduce the use of conventional pesticides. The same fungi can also be used in conjunction with nematodes, providing the potential for a completely organic approach to controlling pests.

Source: Ansari, M.A., Evans, M and Butt, T.M. (2009). Identification of pathogenic strains of entomopathogenic nematodes and fungi for wireworm control. Crop Protection. 28: 269-272.