Researcher grows sunflowers to protect peaches

News From
Division of Agriculture and Natural Resources
University of California

September 30, 2004

If University of California Integrated Pest Management Advisor Walt Bentley has his way, sunflowers will offer a ray of hope in the battle against the oriental fruit moth. The small, grayish insect is a key pest in many stone fruit crops.

The female moth lays eggs inside a peach, and the eggs hatch into larvae which attack the center of the fruit and feed around the pit, making the fruit unfit for consumption.

Macrocentrus ancylivorous is a parasitic wasp that effectively manages the oriental fruit moth. Like the creature from the movie Alien, the wasp lays its eggs inside the pest larva and then the wasp larva develops within, killing the pest.

Unfortunately, the wasp does not winter in the pest, so growers must often spray insecticides. But, if Bentley’s research bears fruit, the parasite will be able to live on caterpillars in sunflowers through the winter, reducing or eliminating the need for insecticide sprays.

“With the pest management products now available, Macrocentrus can be used in a truly integrated program to manage oriental fruit moth,” says Bentley. “Parasitism rates of 70 to 90 percent can mean the difference between doing nothing or having to make a $40 spray application.”

With support from the UC Specialty Crops Grant Program, Bentley has planted sunflowers on a one-acre patch at the Kearney Research and Extension Center in Parlier, California, next to a peach orchard infested with oriental fruit moth. To date, his harvests have showed no damage from the pest.

Bentley’s research shows sunflower moths can help provide a higher population of the beneficial parasite earlier in the season while maintaining the oriental fruit moth at lower levels. Used in conjunction with mating disruption, parasites from sunflowers planted near a crop could control late season infestations.

Mating disruption makes use of the insect's own sexual scents, or pheromones. Researchers tie little chips of the female scent onto branches, confusing the males and disrupting the mating process. Researchers place pheromone dispensers, which are acceptable for produce certified as organically grown, in trees at the first sight of an oriental fruit moth in late February to early March and a second at the beginning of the second flight in May or June.

If the parasite can survive on sunflowers this winter, Bentley hopes it can be integrated into an IPM program that combines mating disruption and biological control to reduce late-season insecticide sprays for oriental fruit moth.