Related link: UC combats invasive species

RIVERSIDE — California's avocado industry is worth more than $320 million annually, and has about 6,000 growers farming more than 60,000 acres of land. Indeed, California grows nearly 95 percent of the country's avocados.

University of California, Riverside entomologist Mark Hoddle is in Peru until the end of July 2010 to work on the avocado seed moth, Stenoma catenifer, a pest native to Mexico, Central America and parts of South America that could wreak havoc on California's avocados should the pest make its way to the state.

"This pest is native to several South American countries, including Peru. It is a known avocado pest in the Chanchamayo region of the Junin district — a somewhat warm and humid jungle zone where avocados are not grown for export," said Hoddle, director of the Center for Invasive Species Research.

Stenoma has a highly localized and contained distribution in Peru. The Junin district is isolated in the Andes Mountains, it has a unique climate, and avocados grown here are consumed locally.

Hoddle, also a biocontrol specialist in the Department of Entomology, and his research team have collected almost 300 pest-infected avocados from orchards and fruit vendors in Junin, and are rearing out Stenoma and its natural enemies in a lab.

"Stenoma collections can only be done in Junin as this is the only area in Peru with this pest," Hoddle explained. "Later, these biocontrol agents will be identified by taxonomic specialists, and described and named if they turn out to be species new to science. This type of information collected in collaboration with overseas trade partners will help us to more confidently identify and manage Stenoma."

When a new pest shows up in California, establishes and causes havoc, oftentimes researchers can be left scrambling for information on how best to develop eradication or management plans.

"We have seen this twice before in California with avocado pests, the persea mite and the avocado thrips," Hoddle said. "Both were species new to science when they first showed up in the United States, and they are the worst two invasive pests California avocado growers need to manage. The persea mite, which is native to Mexico, has also spread to Costa Rica, Israel, and Spain where it attacks avocados.

"We want to get ahead of the curve by proactively working on Stenoma," he said. "We also want to identify any natural enemies Stenoma may have and how effective these biocontrol agents are."

The avocado seed moth can attack close relatives of the avocado, such as greenheart, an important timber tree in South America, and other naturally-occurring plant species of Lauraceae in jungle areas. The pest could possibly attack and survive on California bay laurel, a plant native to California that is closely related to the avocado.

Hoddle noted that Peruvian avocados that are to be exported to California will arrive from export orchards certified by the U.S. Department of Agriculture and located hundreds of miles from the Junin district. These export orchards are located in the coastal desert areas of Peru, one of the world's driest deserts, where vegetation is practically non-existent and food, water and shade for pests are lacking.

To monitor Stenoma that could be infecting Peruvian avocados, the Hoddle team deployed pheromone traps in certified avocado export orchards in the desert and non-certified avocado growing areas in the jungle in Junin.

"The sex pheromone is very attractive to adult male Stenoma," Hoddle said. "As expected, Stenoma has not been trapped in the export orchards located in the coastal desert production regions of Peru. In non-certified export areas in the Junin district, where Stenoma is known to occur, males have been trapped. This is the result we were expecting.

"It is abundantly clear that the sex pheromone we developed for Stenoma from our recent research in Guatemala works in Peru," he said. "We have shown that the pheromone works in Mexico, Guatemala and Brazil. It is likely to work in any country with a Stenoma population — Mexico, all of Central America and parts of South America. Countries exporting or wanting to export avocados should use the Stenoma pheromone to monitor their export orchards for this pest to demonstrate that they are pest-free year round."

In California (San Diego, Riverside, Ventura, and San Luis Obispo counties), Hoddle's team already has set up a proactive monitoring network with the Stenoma pheromone to detect the moth early should it ever arrive in the state and, if need be, eradicate it when populations are still small and highly localized.

For the research project in Peru, Hoddle is partnering with SENASA (Servicio Nacional de Sanidad Agraria), Peru's equivalent of the U.S. Department of Agriculture's Animal Plant Health Inspection Service (USDA-APHIS). SENASA invited Hoddle to Peru to place Stenoma pheromone traps in their export orchards, and provided him with staff and laboratory space to rear out Stenoma inside avocados collected from non-certified export areas.

"Without SENASA's assistance, we would never have been able to access the orchards or our study sites," Hoddle said. "SENASA has been a first class and extremely cooperative partner in this avocado pest survey project. It is obvious that SENASA is very serious about developing world class avocado export orchards and they are taking pest monitoring very seriously."

The California Avocado Commission provided financial support for Hoddle's research trip to Peru. Hoddle is accompanied in this research project by Christina Hoddle, his field assistant.

In mid-August, he will travel to India and Pakistan to study the Asian citrus psyllid and its natural enemies, and to potentially develop a biocontrol project for this pest, which poses a serious threat to California's citrus after its successful establishment in San Diego County in August 2008.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UC Riverside's enrollment of over 19,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UC Riverside Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.