Repellent emitted by redbay may be key to fighting beetles

in Growing Produce

by Paul Rusnak, Growing Produce

UF/IFAS scientists might have just tracked down the right scents to help deter a beetle that’s been delivering disease and devastation to Florida avocado growers.

According to a recently published study, UF/IFAS researchers found when infected with the laurel wilt fungus, redbay trees (a close cousin to the avocado) emit methyl salicylate to repel redbay ambrosia beetles, the vector of the deadly pathogen.

The discovery comes as good news for avocado growers. Some fungicides are available, but they are expensive, said study co-author Xavier Martini, an Assistant Professor of Entomology at the UF/IFAS North Florida Research and Education Center in Quincy. Insecticides are not very efficient because beetles spend most of their time within the wood, he noted.

For the study, scientists compared the number of beetles captured on sticky traps disposed on redbay tree logs. After 10 weeks, they also looked at the holes dug by the beetles into the logs because that’s when the beetles transmit the fungus.

Scientists then tested three different blends of repellent and found verbenone and verbenone plus methyl salicylate — produced by the infected redbay tree — were the most efficient. When scientists applied these repellents on redbay logs, they reduced the number of beetles captured on sticky traps by 95% and the number for boring holes by 90%.

“We believe that these repellents could be used in a larger context, if associated with bug lures to have a push-pull system,” stated Marc Hughes, a former Postdoctoral Researcher in the Forest Resources and Conservation.

In addition to the fact that the repellent — methyl salicylate — seems to work, it is about 80% less expensive than verbenone, Hughes said.

Read more in Growing Produce.

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