Medfly Infestation in Dixon 'One of Many Isolated Pockets of Medfly Infestations in California,' UC Davis Entomologist Says

Sept. 19, 2007 (See story)
"The medfly has been captured in 160 cities in the state. There are 478 cites in California, so medflies have at one time (or are now) present in one of every three cities in the state." --James Carey

The Mediterranean fruit fly (Ceratitis capitata). Click for high resolution. (Photo by Jack Kelly Clark, UC Division of Agriculture and Natural Resources) How and when do you think the medfly arrived in California? I have a theory that the medfly was introduced into the state in the middle of last century, for example, when we had massive movements of troops and supplies into and out of the state during World War II at a time when exotic pest introductions were the least of the state's worries. It is virtually impossible to reconstruct the details of any invasion, though at some point, we may be able to piece together from genetic analysis the geographic origins, rough time frames, how many introductions and so forth. Why is it here and not in some other states, Texas, for example? The medfly is here and not in Texas due to chance. Texas has other exotic pests not found in California that could easily thrive in our state because of chance. Most action agencies view introductions as events, what I call 'tinder box' models where a single 'spark' is all that is needed to start the 'fire.' But history shows that many conditions have to be met to successfully invade. But when an exotic gets a foothold, then it is extremely difficult to eradicate for the same reason that metastatic cancer is difficult to cure; i.e., each of hundreds or thousands of tiny metastases need to be eliminated, otherwise each can generate a separate tumor (population). Elimination of 99 percent of the metastases sounds impressive. But it is still a control concept and not an eradication concept. Once a pest is established in an area, it becomes the source of innoculum and reservoir for the surrounding regions. —James Carey, professor of entomology, University of California, Davis -Kathy Keatley Garvey Communications Department of Entomology (530) 754-6894