Biology Reference
In-Depth Information
through the molt to the adult stage of some wasp larvae and suggest MAPL
may allow host-parasitoid associations to be discovered with precision if DNA
barcode libraries become available for a majority of potential hosts in a specific
geographic area. The use of MAPL also could reveal the use of nontarget hosts
by parasitoids and allow extensive host-parasitoid associations. Note that DNA
from host insects can persist for some time and sensitive PCR analysis methods
can detect it in their parasitoid adults.
13.7.2.2 Analyses of the Establishment of a Parasitoid Released in a Classical Biological
Control Program
Lipolexis oregmae
was imported into Florida and released in a classical biologi-
cal control project as a natural enemy of the brown citrus aphid (
Walker and Hoy
2003
). Another parasitoid,
Lysiphlebus testaceipes
, was known to parasitize this
aphid in Florida, which complicated monitoring for establishment and spread of
L. oregmae
. Traditional methods for monitoring populations of aphids for para-
sitoids involve collecting aphids and holding them in the laboratory until adult
parasitoids emerge. This is labor-intensive and many aphids die from fungal
infections without producing a parasitoid adult.
Persad et al. (2004)
developed a
high-fidelity PCR assay that allowed them to discriminate between immatures of
L. oregmae
and
L. testaceipes
without having to hold the aphids until the adult
parasitoids emerged. The method was efficient and sensitive; a sensitivity analy-
sis of the high-fidelity PCR protocol indicated that adding DNA extracted from
a single parasitoid to the pooled DNA from 300 specimens of the brown citrus
aphid allowed consistent detection of the parasitoid. This method of analysis was
used to indicate establishment had occurred and subsequent analyses, using sin-
gle aphids, could be conducted to indicate the rates of parasitism. This PCR pro-
tocol was used to document that
L. oregmae
had colonized brown citrus aphids
in Jamaica, even before a proposed classical biological control program was con-
ducted (
Hoy et al. 2007
). As a result, the time-consuming and expensive process
of rearing and releasing
L. oregmae
in Jamaica was avoided.
13.7.2.3 Gut Analyses of Predatory Insects to Reveal Prey Species
Generalist insect predators can be difficult to study under field conditions, espe-
cially when they are active in the soil or at night. No-choice studies in the labora-
tory may not reveal the true importance of predation on specific prey species. PCR
analyses of DNA present in predator guts can be used to determine what prey spe-
cies are being eaten if experimental methods are validated (
Foltan et al. 2005, Juen
and Traugott 2005, Sheppard et al. 2005, King et al. 2008, Weber and Lundgren
2009
). Sequences commonly used are the COI and COII fragments of mitochondria
and the internal transcribed sequence 1 (ITS1) region of ribosomal RNA genes in
the mitochondria. RAPD-PCR markers have been tested, but are less often used.
