Fruit flies (Drosophilasuzukii) destroy berries for human consumption by laying eggs under the fruit's skin. The larvae then hatch from the eggs and feed on the berries until they mature. The spotted-wing Drosophila is a fruit fly that can destroy berry crops without heavy use of insecticides. The scent of a crop-destroying fungus could offer an eco-friendly alternative to the toxic chemical, according to a new study.
The fungus Colletotrichumfioriniae is another problem. Among other things, it causes the fruit of the plant to rot, resulting in a significant reduction in yield.
Obviously people don't want to eat rotten fruit, nor do fruit flies want to lay their eggs in it, and once the smell of fruit rot caused by C. fioriniae is detected, the insects will leave the immediate area in search of more intact, uninfected berries.
With this fact in mind, USDA scientists analyzed the volatile chemicals produced when blueberries rot due to infection with C. fioriniae. In laboratory tests, two chemicals, ethyl crotonate and ethyl butyrate, were found to repel fruit flies when they were applied to healthy blueberries, preventing them from laying eggs in the berries. Moreover, the berries were not infected with fungus. This non-toxic chemical is currently being trialled in real agricultural scenarios.
"We started field trials this summer and have already had some very promising results," said research chemist Caitlin Rering, one of the study's lead authors. "We also want to test whether these repellents work on other fruits that are infested by suzukii bugs, such as strawberries, cherries and raspberries."
The paper was published in the journal Pest Management Science.