Biology Reference
In-Depth Information
most differentiated in the Medfly range. An estimation of the probability that
the California Medflies are immigrants from South America, Central America, or
Hawaii was determined using the IMMANC test (
Bonizzoni et al. 2001
).
Bonizzoni et al. (2001)
had three main conclusions: “(i) among the Latin
American and Pacific samples, the Guatemalan flies are most closely related
genetically to the California flies, according to the majority of the tests applied;
(ii) the Californian infestations are structured with the San Diego infestation
being the most differentiated; and (iii) the fact that flies captured between
1992 and 1997 in the Los Angeles basin appear to be genetically related, sup-
ports the hypothesis that an endemic population has been formed in this area.”
Furthermore, “Hawaiian flies show relatively low similarities with Californian
flies,” which indicates Hawaii is not the source of the Californian Medflies
tested, as found by
He and Haymer (1999)
.
Bonizzoni et al. (2001)
concluded that the situation could be more complex
than expected: “Within at least some of the Los Angeles basin samples, there is
considerable evidence for genetic homogeneity. Based on this, the possibility of
an endemic population in California cannot be excluded. It is entirely possible
that independent infestations of this pest from the same geographical region,
overlaid on an existing endemic population, have acted together to create this
unique situation.”
13.7.4.5 The End?
A California Department of Food and Agriculture press release in June 2001
summarized eradication costs since 1975 in California: “more than $256 million
in state and federal funds have been spent eradicating infestations of the pest,
primarily in Southern California and the Bay Area.” The report concluded that
the 5-year test program to stop new infestations by releasing sterile Medflies
in the Los Angeles basin was “enormously successful” because “Between 1987
and 1994, an average of 7.5 Medfly infestations were discovered each year in
California. Since the preventative Release Program began in 1996, there has
been just one infestation for the entire five-year period.”
Over the life of the 5-year “preventative program” that began in 1996, nearly
75 billion sterile Medflies were released from airplanes over
>
2000 square miles
of the Los Angeles basin. This preventative program cost California
≈
US$7.4
million annually and the U.S. government an additional US$7.4 million (CDFA
Legislative Report, March 2000). The report highlighted the fact that, “Since
1994, California's Medfly strategy in Southern California has shifted from a reac-
tive approach, focused on detecting and eradicating early infestations, to a pro-
active approach that emphasizes preventative measures.”
