Agriculture Reference
In-Depth Information
harbourage and competition with other
food items.
Durier and Rivault (2001, 2002b)
reported cockroaches foraging preferentially
on a gel bait over a familiar food source
when it was placed in a new location and
also when the familiar food source was
presented at the same distance (60 cm)
away from the harbourage at a landmark
cockroaches used to associate with the
familiar food. The novelty of the gel bait
became less preferable to cockroaches,
however, when: (i) the placement of the two
food types were interchanged, i.e. gel bait
was placed in the known feeding area and
the familiar food source was placed at the
new location; and (ii) the familiar food
source was located nearer to the harbourage
than the gel bait (30 cm versus 60 cm).
These experiments showed that cockroaches
differentially evaluate the food presented in
their home in relation to its spatial distri-
bution. Compensation for nutrient defi cien-
cies and maintenance of a balanced diet are
some of the reasons why cockroaches
foraged preferentially for novel food in
situations in which they were given a
common food for a period of time (Durier
and Rivault, 2001). However, the benefi t of
the novel food became less obvious to
cockroaches when it was situated further
away from the harbourage than the familiar
food source. In a fi eld study at a swimming
pool facility, food sources nearest to the
harbourage of German cockroaches were
fi rst consumed (Rivault and Cloarec, 1991).
Nevertheless, the presence of a novel food
in a known feeding site in which cock-
roaches used to fi nd their familiar food
resulted in a discrepancy between stored
information and the ongoing situation.
Cockroaches were initially attracted to the
novel food odour placed in a known feeding
site but the visual cues they perceived upon
approaching the familiar landmark contra-
dicted their previous feeding experience.
They identifi ed this local modifi cation as a
potential threat and changed their behaviour
to explore and forage for the safer and
familiar food source that matched their
stored information (Durier and Rivault,
2001, 2002b). From these experiments,
Durier and Rivault (2002b) suggested that
bait, as a novel food for cockroaches, should
be placed in areas nearer to the harbourage
sites.
Studies have also indicated that bait
applied in many small drops or as thin
smears at multiple locations provided
greater control effi cacy than use of a few
large drops in fewer locations (Milio
et al
.,
1986; Appel and Benson, 1995; Durier and
Rivault, 2003b). This could be because
aggression behaviour among cockroaches
interrupts feeding and reduces the number
of cockroaches that can access the bait
(Durier and Rivault, 2003b). The effi cacy of
bait also is greater if it is applied at cock-
roach harbourage sites identifi ed through
placement of traps or visual inspection
rather than at predefi ned locations because
infestation areas vary from house to house
(Silverman and Bieman, 1996). In addition,
a laboratory study (Durier and Rivault,
2003a) indicated that cockroaches were not
always edge followers in their familiar
environment. Baits placed near edges as
well as in the centre of an arena were
equally located and preferred by cock-
roaches. Silverman and Bieman (1996)
reported a similar fi nding in their fi eld
study because baits placed at corners and 25
cm away from corners were equally fed
upon by cockroaches.
Horizontal Transfer of Bait Toxicant
Traditionally, horizontal transfer of insecti-
cides among cockroaches was not con-
sidered to be a trait of cockroach baits
because baits have been constrained by
insecticide resistance (both physiological
and behavioural resistance) and lack of non-
repellent active ingredients (Buczkowski
et
al
., 2001). However, with advancements in
bait technology and a better understanding
of cockroach biology (especially their social
interactions) (Rust
et al
., 1995; Lihoreau
et
al
., 2012), horizontal transfer of bait toxicant
is well documented and now it is one of the
benefi ts of using bait to manage cockroaches
(Kopanic and Schal, 1999; Buczkowski
et
al.
, 2001).
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