Agriculture Reference
In-Depth Information
Bed bugs
extensive spread. In Jersey City, New Jersey,
two or more introductions followed by
spread are evident in two buildings.
Populations within single apartments in all
buildings were characterized by high levels
of relatedness and low levels of diversity,
indicative of foundation from small, gen-
etically depauperate propagules. Regardless
of the number of unique introductions,
genetic data indicate that spread within
buildings is extensive, supporting both
active and human-mediated dispersal within
and between adjacent rooms or apartments
spanning multiple fl oors.
Bed bugs (
Cimex lectularius
L.) are a
resurgent pest worldwide and infestations
within the USA and elsewhere are increas-
ing at a rapid rate. Although bed bug
infestations are spreading and becoming
more prevalent, we have a poor understand-
ing of their dispersal patterns and sources of
infestation. To help fi ll this gap, Saenz
et al
.
(2012) conducted a genetic study of 21 bed
bug infestations from the eastern USA,
nearly all of which came from single rooms
within residences. These authors genotyped
samples comprising 8-10 individuals per
infestation at nine polymorphic micro-
satellite loci. Despite high genetic diversity
across all infestations, with 5-17 alleles per
locus (mean = 10.3 alleles per locus), there
was low genetic diversity (1-4 alleles per
locus) within all but one of the infestations.
These results suggest that nearly all the
studied infestations were started by a small
propagule, possibly consisting of a singly
mated female and/or her progeny, or a
female mated with multiple males that were
highly related to her. All infestations were
strongly genetically differentiated from
each other (mean pairwise
F
ST
between
populations = 0.68) and there was strong
evidence of a geographic pattern of genetic
structure, indicating infestations located in
closer proximity to each other were nearly
as genetically differentiated as those located
hundreds of kilometres away. The high
level of genetic diversity across infestations
from the eastern USA together with the lack
of geographically organized structure is
consistent with multiple introductions into
the USA from foreign sources.
To characterize further the dynamics of
bed bug infestations on a fi ner scale, Booth
et al
. (2012) investigated the population
genetic structure and patterns of dispersal
within three multi-storey apartment build-
ings in the USA. Results reveal contrasting
characteristics potentially representative of
geographic or locale differences. In Raleigh,
North Carolina, an infestation within an
apartment building seemed to have started
from a single introduction followed by
Cockroaches
The German cockroach,
Blattella germanica
(L.) (Blattodea: Blattellidae), is a major
residential pest with the potential to vector
various pathogens and produce and dis-
seminate household allergens. Studies of
B.
germanica
populations between two cities
in France using allozymes (Cloarec
et al.
,
1999) or randomly amplifi ed polymorphic
loci or RAPDs (Jobet
et al.
, 2000) found no
or weak differentiation. Using microsatellite
markers, Crissman
et al
. (2010) investigated
patterns of genetic diversity and differenti-
ation within and among 18 apartments from
six apartment complexes located in Raleigh,
North Carolina. No departure from panmixia
(random mating) was found between rooms
within apartments, indicating that active
dispersal resulting in gene fl ow may occur
among rooms within apartment units.
Alternatively, aggregations within apart-
ments may exist in relative isolation under
a metapopulation framework, derived from
a recent, common source. Thus, in the event
of population control practices leading to
incomplete cockroach eradication within
an apartment, recolonization of shelters and
rooms is likely to occur from a genetically
similar aggregation. A pattern of isolation-
by-distance across the six apartment com-
plexes indicated that dispersal was more
common within complexes than among
them and
F
-statistics suggested greater
genetic similarity between apartments in a
Search WWH ::
Custom Search