UC Davis experts: Mediterranean fruit fly

UC Davis has faculty experts who can provide background and comment on the Mediterranean fruit fly, which recently appeared in Dixon, just west of Sacramento, Calif.

Science of invasion

Although the recent discovery of Mediterranean fruit flies in Dixon, Calif., appears to be an isolated infestation, a UC Davis Medfly expert suggests that this serious agricultural pest may have been multiplying and spreading undetected throughout the state for many years. James Carey, an entomology professor and expert on insect demography, says that officials need to consider how invasive species move into a new area and treat the appearance of the pest like a disease, not just a symptom. During the Medfly outbreaks of the late 1980s and early 1990s, Carey served on the Medfly scientific advisory panel for the California Department of Food and Agriculture. In 1991, he published a historical analysis of Medfly infestations in the journal Science, supporting the notion that the Medfly was established in California, rather than being repeatedly introduced by trade or travelers. Contact: James Carey, Entomology, (530) 752-6217 or 754-6209, .

Medfly control

During the California Medfly infestations of the 1980s and 1990s, the aerial spraying of the pesticide malathion became the focus of great public concern. But an organic Medfly-control compound called spinosad, developed from naturally occurring soil bacteria, should pose little concern, says UC Davis entomologist Frank Zalom, an expert on environmentally sensitive pest control methods. He notes that the spinosad bait has been used successfully by California growers to treat olive fruit flies and in Hawaii to suppress Medflies. The compound is relatively fast acting, killing pests within one or two days, and is quickly broken down into harmless carbon, hydrogen, oxygen and nitrogen in the environment. Spinosad is being used in tandem with the aerial release of sterile male Medflies, which mate with any fertile females that may be present so that they will not produce offspring. Zalom, an integrated pest management specialist, studied the ability of Medfly populations to survive through the winter, while on a Fulbright fellowship in Spain. Contact: Pat Bailey, News Service, (530) 752-9843, .

Economic and policy impacts

The Mediterranean fruit fly and other exotic pests -- those not native to a particular country, region or state -- present a host of challenges to policymakers charged with preventing their introduction, and controlling or eradicating them should they arrive. Daniel Sumner, a UC Davis agricultural economist and director of the UC Agricultural Issues Center says that the expansion of global trade has made exotic pests and diseases an urgent and complex problem for agriculture. Sumner can discuss the economic consequences of policy alternatives for controlling or eradicating the Medfly. He edited the book "Exotic Pests and Diseases: Biology and Economics for Biosecurity," published in 2003. The book, which examines complicated policy issues, contains individual case studies that focus on 14 specific diseases or pests. Contributors to the book considered the impact on California's domestic and international trade of potential exotic pest problems. Contacts: Daniel Sumner, Agricultural Issues Center, (530) 752-1668, .

Media contact(s):

• Pat Bailey, UC Davis News Service, (530) 752-9843,

• Claudia Morain, UC Davis News Service, (530) 752-9841,

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