Biology Reference
In-Depth Information
13.7.6 Origins of Insect Populations
It is often the case that pest managers and regulatory agencies want to know
the origin of an invasive pest. Knowing the origin may allow the regulatory
authorities to develop improved inspection methods for cargo and improved
quarantine procedures. Scientists may want to predict the distribution of the
pest in the new environment based on the origin of the pest population. If clas-
sical biological control is to be conducted, it is desirable to know the origin of
the pest so that the most effective natural enemies can be identified for evalua-
tion, importation, release, and establishment. The following examples illustrate
the approaches taken to study the origins of several insect populations.
13.7.6.1 Emerald Ash Borer
The emerald ash borer (EAB),
Agrilus planipennis
(Buprestidae), is a wood-
boring pest of ash that was discovered to have invaded North America in 2002.
It spread from its original infestations in Michigan and Ontario, Canada rapidly,
so that as of 2011 it can be found in 15 states in the United States and in two
provinces in Canada. Larvae of the EAB have killed tens of millions of ash trees
in North America by feeding under the outer bark on phloem and outer sap-
wood. Adults exit the trees within 1 or 2 years to attack new trees.
The EAB is known to occur in Asia, including China, Japan, Korea, Mongolia,
Taiwan, and the Russian Far East. Beetles from 17 areas in Asia and from 7
localities in North America were analyzed using mitochondrial DNA sequences,
AFLP fingerprints, and two microsatellite loci (
Bray et al. 2011
). The COI mito-
chondrial sequences indicated that all North American beetles could have come
from China or South Korea. The 108 AFLP fingerprints indicated that the North
American populations most resembled beetles in Hebei and Tianjin City and
were most likely the result of a single introduction from China. The genetic
diversity of the North American beetles was reduced compared to the beetles
studied from Asia.
Bray et al. (2011)
concluded that the EAB probably invaded
North America only once, even though the first sites were geographically distant
(or that the invasions were from the same source because it was not possible
to distinguish the Ontario population from the other North American popula-
tions tested). However, the authors suggest additional analysis of beetles from
other locations in Asia is desirable. The results obtained have allowed searches
for natural enemies of the EAB in Asia, and releases of three parasitoid species
have been made.
13.7.6.2 Domesticated Populations of
Aedes aegypti
The mosquito
Aedes aegypti
is a vector of dengue and yellow fever viruses and
is thought to have originated in sub-Saharan Africa, breeding in tree holes in
