Medfly Wars

“The war is over—again,” wrote reporter Pat Brennan of the Orange County Register in a news article published Aug. 14.

Brennan was referring to the war against the Mediterranean fruit fly, a tiny pest that targets some 260 crops. The pest, first detected inCaliforniain 1975, prefers such hosts as peach, nectarine, apricot, avocado, grapefruit, orange and cherry. It is considered the world's worst agricultural pest.

California State Department of Agriculture had earlier announced the eradication of the medfly in three counties:Los Angeles, Solano andSanta Clara.If it were to become permanently established in California, the medflycould cost the state  $1.3 to $1.8 billion in annual losses,  estimated CDFA Secretary A. G. Kawamura.

I remember whenSolanoCountyag officials discovered four live medflies in a single trap in downtownDixon. The date:  Monday, Sept. 10, 2007. Newspapers bannered the story. A quarantine ensued.   Farmers fretted, and rightfully so.  Later I attended a press conference at theNutTreeAirport, Vacaville;a pilot had just released the first of many millions of sterile male fruit flies over Dixon. He showed us the  sterile medflies, dyed pink.

The sterile flies mate with wild flies and biologically force wild populations out of existence, the CDFA says.

UC Davis entomologist James Carey, who has published widely on the medfly, said the pest has been multiplying and spreading undetected--like cancer--for years in California.  He says it's never been really eliminated and he questions whether it could ever be eradicated.

CDFA and Solano County ag officials said no; that an errant tourist likely brought it to Dixon on a piece of fruit fromHawaii. The medfly lays its eggs inside fruit.

Medfly wars ensued.

Carey shared an email he sent Aug .14 to Brennan:

“The absence of medfly appearances anywhere else in the continental U.S. besides California over the past two decades strongly supports the argument that the medfly has never been completely eradicated in our state. CDFA's efforts at eradication have been successful at driving the populations back to subdetection levels for a few years. However, the reappearances of the medfly in the same cities and even in the same locations within these cities is due to a long-term established population.  Although I fully acknowledge the need to respond to the medfly when it appears in the state as it did last year, I have no reason to believe that this program will have been any more successful than the previous ones which merely suppressed rather than eliminated the medfly population from the state."

“This recent declaration of eradication is around the 50th emergency response to medfly outbreaks over the past two decades by CDFA, virtually all of which have been in the same general locations. To my knowledge during this same period no other state such as Arizona, Florida or Texas has experienced any outbreaks even though these states, like California, have climates suitable for the medfly establishment and have many tourists and migrants who are capable of introducing the medfly. These states have experienced no outbreaks while California has experienced 50.”

The CDFA Web site says medflies are not established in California. 

"These (medflies) and other exotic pests have not become established in California due to (1) strict federal exterior and state interior quarantines, (2) a pest detection program, and (3) aggressive eradication programs when an infestation is discovered."

Carey, who has plotted all medfly finds in California, says medfly populations  “do not really get going until late summer and fall. Stay tuned for this fall.”

One thing is certain: the little bugger draws a lot of attention. That's because, as Brennan wrote, it “attacks so many crops.”