Agriculture Reference
In-Depth Information
criterion for bait with secondary kill effects
because it determines whether a lethal dose
is being ingested and it infl uences the
amount of toxicant available for horizontal
transfer. Consumption of more bait means
that poisoned individuals will defecate or
regurgitate more materials containing toxi-
cant and contain more toxicant within the
cadaver (Silverman
et al
., 1991; le Patourel,
2000; Buczkowski and Schal, 2001a). In a
laboratory study, Durier and Rivault (2000a)
documented that German cockroaches often
chose Goliath gel bait (0.05% fi pronil) in
preference to Avert (0.05% abamectin),
Maxforce (2.15% hydraethylnon), and Drax
(33.3% boric acid) gels. Nevertheless,
Maxforce and Avert gels stimulated more
feeding than Goliath because they induced
longer feeding duration on the bait.
Furthermore, certain attractants and
feeding stimulants are species specifi c and
mixtures of these substances may have
synergistic effects (Tsuji, 1965, 1966; Wada-
Katsumata
et al
., 2013). Previously, Tsuji
(1966) demonstrated that several fatty acids
and related compounds were both attractive
and a feeding stimulant to
P. americana
,
P.
fuliginosa
and
B. germanica
, whereas cer-
tain compounds acted as species-specifi c
attractants or feeding stimulants. In a study
(Wada-Katsumata
et al
., 2013), a mixture of
glucose and fructose stimulated a higher
feeding rate and a greater response of sugar-
gustatory receptor neurons in wild-type
B.
germanica
than either fructose or glucose
alone.
The nature of bait formulation also
affects cockroach mortality. Studies have
shown that indoxacarb and abamectin gel
baits resulted in faster mortality (lower
LT
50
)
of German cockroaches than powder
formulations with a similar concentration
of the active ingredient (Buczkowski
et al
.,
2001; Appel, 2003). Buczkowski
et al
.
(2001) attributed this difference to the
secondary kill effect of the bait. They found
that hydramethylnon gel bait caused
signifi cantly more secondary mortality in
adult German cockroaches than the solid
block of hydramethylnon in a bait station.
In general, gel baits are superior to solid
ones for secondary transfer of toxicant
because gels are effi ciently consumed and
excreted from the insect body and therefore
more readily available for horizontal
transmission (Buczkowski
et al
., 2001).
Durier and Rivault (2002a) reported that the
effi cacy of bait could also be attributed to
the design of the bait station. They
demonstrated that German cockroaches
were attracted by a novel object introduced
into their foraging home range. When the
complexity of the introduced object
increased, such as a bait station with several
entrances, German cockroaches spent more
time exploring the exterior and inner parts
and were even more attracted to it if it
contained food. The attractiveness of the
bait station enhanced its effi cacy and was
especially important for bait containing
toxicant with contact toxicity because it
retained the cockroaches for a longer period
of time, allowing more toxicant to be picked
up (Durier and Rivault, 2002a).
Cockroach Foraging Behaviour
An urban environment composed of com-
plex manmade structures and resources
invites cockroaches to fi nd harbourages and
establish an infestation. At nightfall, cock-
roaches begin to leave their daytime
harbourage sites to forage for resources and
seek mates, and their activities normally
peak approximately 2-4 h after sunset
(Mellanby, 1940; Appel and Rust, 1986).
Importance of path integration
Studies of the foraging strategies of
cockroaches using
B. germanica
as a model
revealed that cockroaches are aware of the
spatial distribution of resources in their
environment, and they exhibit effi cient
foraging trips between resources and
harbourage sites (Demark
et al
., 1993; Durier
and Rivault, 2001, 2003a). Although
cockroaches live in an aggregate, they forage
in their environment individually based on
their own knowledge of their surrounding
environment; they do this by using path
integration and previously experienced
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