Preventing the destruction of Eucalyptus forest plantations: naturally occurring pathogenic fungi to control the Eucalyptus snout beetle

Scientists have found naturally occurring pathogenic fungi infecting the Eucalyptus snout beetle in Eucalyptus forest plantations, and characterised them to develop a bio-pesticide for controlling the beetle.

Gonipterus platensis, or the Eucalyptus snout beetle, has a heavy impact on Eucalyptus forest plantations worldwide, and it is mostly controlled using the micro wasp Anaphes spp., although control rates rarely become financially viable. This led a team of scientists to look for naturally occurring pathogenic fungi to tackle the Eucalyptus snout beetle problem.

Worldwide, the Eucalyptus forest covers more than 20 million hectares. In the Iberian Peninsula, the Eucalyptus snout beetle could cause defoliation levels of 100% and produce wood volume losses of up to 86%. Although Eucalyptus wood is important for paper pulp production, the biological control of the Eucalyptus snout beetle is far from total, and on some occasions chemical control is needed, too. 

The identification of fungi pathogenic to the Eucalyptus snout beetle is not new. What is remarkable in this new research is that the scientists collected the fungi from naturally infected beetles in the current distribution area in Colombia, so the fungi will be well-adapted to the environmental conditions, which is promising for controlling the beetle in forest plantations.

To ensure that the recovered fungi are suitable for developing a bio-pesticide, the scientists characterized them in terms of insecticidal activity, UV-B radiation tolerance and other parameters. This characterisation ensures that the fungi are suitable for mass production of a bio-pesticide and, when used in forest plantations, are resistant to the environmental conditions. Beauveria pseudobassiana and Metarhizium brunneum were the most virulent fungi. B. pseudobassiana was the most adapted for producing a bio-pesticide and tolerant to the environmental conditions.

The fungi could be used to develop a bio-pesticide, after trials in Eucalyptus forests. Later, the fungi could also be used in other countries where the insect is causing severe damage.

This work was supported by the Ministry of Agriculture and Rural Development, Colombia, through Corporación Colombiana de Investigación Agropecuaria – AGROSAVIA, as part of the project “Strategies for planning and management of forest plantations and agroecosystems in Colombia”. The scientists are looking for new funding to run tests in field conditions.