USA: Battling avocado-ravaging disease

by Tim Sandle, Digital Journal


Redbay ambrosia beetles carry laurel wilt disease and they are a serious threat to avocado trees. To combat this, a research group seem to have found a biological control to eliminate the beetles.


Red ambrosia beetles bore holes in trees and carry with them a fungus that causes laurel wilt. The redbay ambrosia beetle is a small, black or amber-brown, cigar-shaped beetle under two millimeters in length. Laurel wilt is a vascular disease caused by the fungus Raffaelea lauricola. The main risk is to avocados in the U.S., especially in California and Florida.

The problem is a relatively new one. The beetles, native to India, began to appear in the U.S. in 2002. By 2005 the damage to avocado trees became apparent and the beetle-fungus link was established.

The only means to control the beetles at present is the use of insecticides, but these potent chemicals carry their own risks. As an alternative, scientists based at Tropical REC and the Indian River Research and Education Center in Fort Pierce have identified a different type of biological control: a different type of fungus.

To test out the new method, the researchers exposed beetles to three commercially available fungi, and all of the beetles died. Next they proceeded to sprayed the fungi on avocado tree trunks, and beetles got infected while boring into the trunk. Here they saw two-thirds of the beetles dying. This could help to reduce the level of insecticides used.

The aim is to use the fungal treatments to prevent the beetles from boring into the trees which would prevent the disease causing fungus from entering.

The research was carried out at the University of Florida. The research outcome has been published in the journal Biological Control, in a paper titled “Entomopathogenic fungi as biological control agents for the vector of the laurel wilt disease, the redbay ambrosia beetle, Xyleborus glabratus(Coleoptera: Curculionidae).”


Source: Digital Journal

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