Biology Reference
In-Depth Information
use frass (excreta) or larval exuviae as sources of DNA for multiplex PCR for iden-
tifying the larvae of the two species. There was sufficient DNA present in the
frass as long as 7 days after it was excreted to produce a PCR product.
13.8.2 Monitoring Vectors of Disease
Monitoring mosquitoes that are vectors of disease for the presence of the
pathogen is an important component in managing diseases affecting human
and animal populations. Various approaches have been tested, including clini-
cal diagnoses of symptoms or detection of the pathogen in the vectors. Sentinel
animals are used to determine whether a disease outbreak is impending. Virus
surveillance of the mosquitoes is based on isolating the virus from mosquitoes
collected in traps.
Hall-Mendelin et al. (2010)
developed a novel method to
detect viruses in mosquitoes that involves attracting the mosquitoes to a carbon
dioxide-baited trap where they can feed on honey-soaked nucleic-acid preserva-
tion cards in the trap. The mosquitos expectorate the virus into the honey while
feeding, and the cards can then be analyzed by reverse-transcriptase PCR.
Hall-
Mendelin et al. (2010)
detected Ross River and Barmah Forest viruses in these
cards taken from traps in Australia and found the viral RNA was preserved for at
least 7 days. The use of the cards reduced handling of mosquitoes or processing
them to extract viral RNA.
A heteroduplex PCR reaction was developed by
Lee et al. (2002)
to identify
what bird species
Culex tarsalis
mosquitoes had fed on among 16 possible hosts.
The assay used primers amplifying a fragment of the cytochrome B gene from
the 16 bird species and this gene could be detected 7 days after feeding by the
mosquitoes. Information on host range is important in understanding the rela-
tionship between mosquitoes and their normal hosts and determining how
pathogens get transmitted to humans or other animals. Epidemics in humans
or other animals often can only occur when “bridge species” of mosquitoes
transmit the virus (or other pathogen) to them because many mosquitoes are
restricted in their host range and rarely bite humans. Thus, knowing the natu-
ral source of the pathogen can be important in monitoring for and predicting
potential epidemics.
13.8.3 Pesticide Resistances and Pest Management
Pest managers would like to identify pesticide resistances in pests and improve
their ability to design novel pesticides (
Perry et al. 2011
).
Perry et al. (2011)
argue that resistance studies in
Drosophila melanogaster
could elucidate bio-
chemical and genetic mechanisms underlying resistance in many insects because
genes and metabolic activities in all insects are conserved and the advances in
