Sustainable Cockroach Management Using Insecticidal Baits: Formulations, Behavioural Responses and Issues - Urban Insect Pests: Sustainable Management Strategies - page 78

Table 5.1. Insecticide resistance profi les of fi eld-collected strains of B. germanica against several
insecticides commonly used in cockroach baits based on LD 50 values obtained from topical bioassays.
Active ingredient (class of
insecticide)

Resistance ratio
based on LD 50 Location Reference

Abamectin (avermectin) 2.5 Ohio, USA Wang et al ., 2004

6.8 Indiana, USA Wang et al ., 2004

Imidacloprid (neonicotinoid) 10 Alabama, USA Wei et al ., 2001

1.8-3.8 Singapore Chai and Lee, 2010

7.6 Florida, USA Gondhalekar et al ., 2011

Indoxacarb (oxadiazine) 1.9-5.3 Singapore Chai and Lee, 2010

5.9 Florida, USA Gondhalekar et al ., 2011

Fipronil (phenylpyrazole) 2.3 Alabama, USA Wei et al ., 2001

8.7 Ohio, USA Wang et al ., 2004

9.3 Indiana, USA Wang et al ., 2004

2.0-15.0 Denmark Kristensen et al ., 2005

2.0-10.0 Singapore Chai and Lee, 2010

37.9 Florida, USA Gondhalekar et al ., 2011

2.1-44.8 Indonesia Rahayu et al ., 2012

continuous sublethal exposure to the
insecticides used in baits. Holbrook et al .
(2003) described conditions in which sub-
lethal exposure may occur, such as through
ingestion of lower doses of insecticide
deposited within oral and anal excretions
produced by bait-fed cockroaches and
exposure to lower doses of insecticides
used in ant and termite management pro-
grammes. In addition, B. germanica may
ingest sublethal doses of an active ingredient
in bait when feeding is interrupted because
of aggressive behaviour among individuals
within a feeding aggregate (Durier and
Rivault, 2003b) or when they are partially
satiated after feeding on alternative food
sources before consumption of bait
(Reierson, 1995). In a laboratory study,
fi eld-collected B. germanica strains sub-
jected to bait selection (0.05% fi pronil and
0.6% indoxacarb baits) for fi ve generations
exhibited a steady increase of physiological
resistance levels (Ang et al., 2013). Due to
palatability of baits, these F 5 generation
cockroaches with increased physiological
resistance exhibited only low levels of
resistance to gel baits and 100% mortality
was achieved by bait treatment within 14
days. This study demonstrated that resist-
ance level can be enhanced under baiting
conditions, but whether the selection
pressure will result in control failure in the
fi eld remains to be seen. If increasingly

higher doses of toxicant are required for
toxic baits to be effective, high-dose manage-
ment strategies may only provide short-
term solutions (Gondhalekar and Scharf,
2012). Alternatively, rotation of toxic baits
with active ingredients with different
modes of action could be a feasible way to
reduce the potential risk of insecticide
resistance development (Gondhalekar et al .,
2013).

Bait aversion behaviour

Another major challenge to overcome in
cockroach baiting is the phenomenon of
glucose and bait aversion in German cock-
roaches . Silverman and Bieman (1993)
reported control failure for hydramethylnon
bait containing glucose in a study conducted
in Florida. They found that avoidance of the
glucose used in the bait formulation was
responsible for this phenomenon. Glucose
aversion is an inherited trait rather than a
learned trait (Silverman and Bieman, 1993;
Wang et al ., 2006). Subsequently, glucose
aversion was found among fi eld strains of B.
germanica from other locations in the USA
and South Korea (Silverman and Ross,
1994). In Malaysia, screening of the 41
strains of B. germanica collected from the
fi eld revealed that 12% of the strains
exhibited a negative response to glucose