Using drone & satellite to track pest damage
FABI and ICFR researchers are collaborating in an innovative project to develop a system to monitor the impact of the Eucalyptus snout beetle on the health of eucalypts using a combination of drones and satellite remote sensing.
Gonipterus sp. n. 2, is an invasive insect native to Australia and a significant defoliator of Eucalyptus. Management of this pest, commonly known as the Eucalyptus snout beetle, relies mainly on classical biological control by a tiny wasp Anaphes nitens, which was first introduced into South Africa in 1924. The biological control has been effective in keeping Gonipterus infestations under control for decades, but in the past few years Gonipterus infestations have increased and the damage to eucalypt plantations in South Africa is on the rise.
The project is a collaboration between the Forestry and Agricultural Biotechnology Institute (FABI) based at the University of Pretoria, the ICFR’s Dr Ilaria Germishuizen and Dr Benice Sivparsad and international researchers Prof Wouter Maes of the University of Ghent in Belgium and Dr Rene Heim of the Institut für Zuckerrübenforschung.
Gonipterus is a small beetle with a distinctive X mark on its back. It eats mainly along the leaf margins, leaving a characteristic scalloped leaf edge. It prefers new growth on E. dunnii, E.smithii and hybrids. Gonipterus larvae.
The use of a drone to measure Gonipterus damage is key as it provides very high resolution images of the tree canopy that cannot be seen from ground level once trees reach more than 2 m height. The satellite imagery is useful in that it can detect canopy damage but is not fine enough to provide the detailed information that the researchers require.
The project has two main objectives:-
• To use satellite and drone imagery to assess and monitor the extent of canopy damage from Gonipterus.
• To understand the relationship between the canopy damage and the productivity of the compartment, which will provide forest managers with the info necessary for them to decide when and where to incur the costs of applying a chemical spray to reduce Gonipterus infestations. The info gathered from the study will also enable the researchers to assess the impact of a chemical spray application on the population of the biological control agent A. nitens.
The drone provides detailed images of the tree canopy from above, allowing researchers to gauge Gonipterus damage. (Photo courtesy of FABI)
The model that will be developed through this study will be applicable to monitor the impacts of other pests and diseases that defoliate eucalypts.
Earlier this year PhD candidate Phumlani Nzuza, Dr Michelle Schroder and Ofentse Mathibela from FABI went to the KwaZulu-Natal midlands to map Gonipterus sp. n. 2 defoliation levels using their newly acquired drone. For field ground truthing they are using ICFR’s Gonipterus impact trials at Hodgsons (Greytown) and Sutton (Ixopo)
The ICFR’s work is supported by FSA, Sappi, NCT and TWK.