Biology Reference
In-Depth Information
In 2010, the Medfly controversy erupted again (
Chen 2010
).
Carey (2010)
reas-
serted that the Medfly was established in California and stated, “To the extent
possible, scientific questions and policy questions should not be conflated.
Whereas the primary responsibility of scientists is to pursue scientific truths,
the principal responsibility of policy makers is to formulate policy on the basis
of these truths.”
Carey (2010)
reiterated that repeated invasions were unlikely
the source of Medflies in California.
Liebhold et al. (2010)
responded to Carey
by reviewing an earlier paper in which they evaluated 190,101 interceptions of
alien insects at U.S. airports between 1984 and 2000, with 43% of the intercep-
tions consisting of fruit infested with insects (especially mangoes). Tephritidae
consisted of 33% of the interceptions. However, “While there is little doubt that
Medflies have consistently arrived in California at relatively high rates in fruit
associated with baggage, the question of whether the species has persisted for
many years or whether it has been repeatedly introduced and then eradicated
remains, in our opinion, unresolved” (
Liebhold et al. 2010
).
Diamantidis et al. (2008)
compared biological traits of wild Medflies obtained
from Kenya, Greece, Portugal, Brazil, Guatemala, and Hawaii under identical
laboratory conditions. The F
1
generation of each population was studied and
showed differences in life span, age-specific oviposition, and differences in sex-
ual behavior, although Medflies from different areas were able to interbreed.
However, the divergences in life history and behavioral traits suggest consider-
able evolutionary changes have occurred as this species has colonized new geo-
graphic areas.
Using a demographic system model,
Gutierrez and Ponti (2011)
evaluated the
effects of temperature on Medfly's potential distribution in Arizona, California,
and Italy. Their model predicts that the area of potential favorability is the south
coastal region of California, especially the urban areas of the Los Angeles basin.
Other regions of California might be suitable for some years, but not continu-
ously over several years and their analysis “suggests that temperatures in much
of CA are simply outside of medfly's thermal envelope.
…
and “if the fly is
established in CA, its permanence is tenuous. In contrast, Medfly is established in
Italy, and our model predicts the wide geographic favorability observed there”
(
Gutierrez and Ponti 2011
).
Classical biological control has been suggested as a possible management tool
for the Medfly in California (
Headrick and Goeden 1996
). However, a biological-
control program typically would not be conducted unless there is a good prob-
ability that the Medfly is established (which would create economic and political
problems in California).
