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Knockdown and Lethal Effects of Eight Commercial
Nonconventional and Two Pyrethroid Insecticides against
Moderately Permethrin-resistant Adult Bed Bugs, Cimex
lectularius (L.) (Hemiptera: Cimicidae)
WILLIAM A. DONAHUE, JR.*1, ALLAN T. SHOWLER2, M. W. DONAHUE1,
B. E. VINSON1, LUCIA HUI3AND WESTE L.A. OSBRINK2
1Sierra Research Laboratories, 5100 Parker Road, Modesto, CA 95357, USA
2USDA-ARS KBUSLIRL, 2700 Fredericksburg Road, Kerrville, TX 78028,USA
3Alameda County Vector Control Services District, Department of Environmental Health, 1131
Harbor Bay Parkway, Alameda, CA 94502, USA
————————————————————————
Biopestic. Int. 11(2): 108-117 (2015)
ABSTRACT The common bed bug, Cimex lectularius (L.) (Hemiptera: Cimicidae) is undergoing
a rapid resurgence in the United States during the last decade which has created a notable
pest management challenge largely because the pest has developed resistance against DDT,
organophosphates, carbamates, and pyrethroids, the latter class of insecticide being most
commonly used today. Eight nonconventional insecticides Orange Guard (a.i., d-limonene),
Natria Home Pest Control (a.i., soy bean oil and eugenol), RestAsure (a.i., sodium laurel
sulfate, sodium chloride, and potassium sorbate), CedarCide (a.i. cedar oil), Essentria Broadcast
Insecticide (a.i., 2-phenethyl propionate, rosemary oil, and peppermint oil), EcoSmart Organic
Home Pest Control (a.i., 2-phenethyl propionate, clove oil, rosemary oil, peppermint oil, and
thyme oil), Cirkil (a.i.,neem oil) and CimeXa (a.i., silica gel) were compared with two pyrethorids
Bonide Bedbug Killer (a.i.,permethrin) and D-Force (a.i.,deltamethrin) as positive controls, and
water for direct contact spray knockdown and lethal effects in the laboratory over 4 days.
Orange Guard, CedarCide, Essentria, EcoSmart, and Cirkil provided extensive knockdown within
15 min (recovery was, at most, negligible), and caused 80 to 100% mortality within a day
making them as effective as the two pyrethroids. CimeXa did not cause appreciable knockdown,
but nearly complete mortality was achieved within a day. Product effects in terms of active
ingredients and factors that might increase and decrease product effectiveness, such as cimicid
aggregation behavior and residual effects, are discussed.
KEY WORDS : Cedar oil, d-limonene, essential oils, eugenol, mode of action, neem oil, peppermint
oil, rosemary oil, silica gel, sodium laurel sulfate
————————————————————————
0973-483X/11/108-117©2015 (KRF)
INTRODUCTION
The bed bug, Cimex lectularius (L.) (Cimicidae:
Hemiptera), is a flightless obligatory hematophagous
parasite of man, bats, poultry, and many domestic
animals (Usinger, 1966; Ebeling, 1975). Cimex
lectularius infestations cause emotional distress,
Mention of trade names or commercial products in this publication is solely for the purpose of providing
specific information and does not imply recommendation or endorsement by the U.S. Department of
Agriculture and by Alameda County Vector Control Services District, Department of Environmental Health.
2015 Donahue et al.: Effect of natural products on cimicidae 109
sleeplessness, and anxiety (Potter, 2006). Public
tolerance for C. lectularius bites in the United States
is almost zero, and litigation, especially involving
hotels, is becoming common (Potter, 2006, 2011). Over
the last decade, pest control professionals have
reported significant increases of C. lectularius
infestations in the United States and in developed
countries worldwide (Potter, 2006; Cooper, 2011).
Explanations for this resurgence include reduction
of baseboard spraying of synthetic pesticides for
cockroach control following the introduction of
effective baits in the early 1980s, resistance to
insecticides, loss of efficacious organophosphates
and carbamates as treatment options after enactment
of the Food Quality Protection Act (1996), increased
international travel, and lack of awareness by the
public and pest management professionals (Silverman
and Shapas, 1986; Shurdutet al., 1998; Potter, 2006;
Romero et al., 2007; Cooper, 2011). Cimex lectularius
has developed resistance against DDT,
organophosphates, carbamates, and pyrethroids, the
latter class of insecticide being most commonly used
today (Romero et al., 2007; Davies et al., 2012;
Koganemaru and Miller, 2013). The rapid resurgence
of C. lectularius in the United States during the last
decade has created one of the most difficult pest
management challenges in a generation (Potter, 2006;
Potter et al., 2008; Koganemaru and Miller, 2013) and
there is a critical immediate need for new insecticides
to achieve control.
As C. lectularius resistance to conventional
insecticides increases, alternative control tactics,
such as application of bioactive natural products that
often involve multiple compounds with different
modes of action warrant investigation and
development. Different modes of action in the same
nonconventional insecticide can reduce the risk of
insecticide resistance. Botanical products that
contain bioactive compounds are desirable for pest
management when they are effective and benign to
natural enemy populations (Schmutterer, 1990, 1995;
Ascher, 1993). Many are considered to be minimum-
risk pesticides and are exempt from Environmental
Protection Agency (EPA) registration under section
25(b) of the Federal Insecticide and Rodenticide Act
(Cloydet al., 2009). While some claims of success
using nonconventional insecticides against C.
lectularius are anecdotal, a limited number of
nonconventional insecticides, including botanically-
based formulations and desiccating powders, have
been scientifically assessed and were found to be
efficacious against C. lectularius (Anderson and
Cowles, 2012; Akhtar and Isman, 2013; Hinson et
al., 2014; Wang et al., 2014; Goddard and Maschek,
2015). Because the need for assessing rapid effects
of nonconventional insecticides is becoming more
apparent as C. lectularius resistance to conventional
insecticides continues to develop and C. lectularius
infestations spread and intensify, we assessed the
direct contact efficacy of eight nonconventional
commercial insecticides, each with different active
ingredients, for C. lectularius suppression by means
of knockdown and mortality.
MATERIALS AND METHODS
Assays were conducted at Sierra Research
Laboratories in Modesto, Stanislaus County, CA,
during March and April 2014. Sierra Research
Laboratories-WMB strain C. lectularius (L.), with
moderate permethrin resistance (10×) were used. The
treatment products were Orange Guard (EPA reg. no.
61887-1-AA, Orange Guard, Carmel Valley, CA) ready
to use (RTU) emulsion with the active ingredient
listed as being d-limonene (5.8%); Natria Home Pest
Control (EPA reg. exempt, Bayer, Environmental
Science, Research Triangle Park, NC) RTU emulsion
with active ingredients soy bean oil (3%) and
eugenol (0.25%); RestAsure (EPA reg. exempt,
RestAsure, St. Louis, MO) RTU emulsion with active
ingredients sodium laurel sulfate, sodium chloride,
and potassium sorbate (proprietary mixture);
CedarCide (EPA reg. exempt, CedarCide, Lewisville,
TX) RTU emulsion with active ingredients cedar oil
(5-20%) and hydrated silica (80-95%); Essentria
Broadcast Insecticide (EPA reg. exempt, Envincio,
Cary, NC) RTU aerosol with active ingredients 2-
phenethyl propionate (3%), rosemary oil (1.5%), and
peppermint oil (2%); EcoSmart Organic Home Pest
Control (EPA reg. exempt, Alpharetta, GA) RTU
emulsion with active ingredients 2-phenethyl
propionate (2%), clove oil (1%), rosemary oil (1%),
peppermint oil (1%), and thyme oil (0.5%); Cirkil RTU
110 Biopesticides International Vol. 11, no. 2
(EPA reg. no. 88760-1, Terramera, Buena Park, CA)
RTU emulsion with cold pressed neem oil as the
active ingredient (5.5% cold pressed neem oil);
CimeXa (EPA reg no. 73079-12, Rockwell Labs,
Kansas City, MO) with silica gel dust as the active
ingredient (100%); Bonide Bedbug Killer (EPA reg.
no. 4-358, Bonide Products, Oriskany, NY) RTU
emulsion with permethrin as the active ingredient
(0.5%) as a positive control; and D-Force (EPA reg.
no. 279-9554, FMC, Philadelphia, PA) RTU aerosol
with deltamethrin as the active ingredient (0.6%) as
another positive control to which the strain of C.
lectularius used in this study was not known to be
resistant. All of the treatments were obtained from
various retail sources, and the control was tap water.
Treatment units were each comprised of 10 adult
C. lectularius inside a 336-mL plastic cup (Kal-Clear
KC12S, Fabri-Kal, Kalamazoo, MI) on a cone coffee
filter at the bottom to absorb excess liquid. Plastic
Kal-Clear domed lids to the cups each had a 2.5-cm
diameter hole at the apex through which the
treatment formulations were sprayed using a 710-mL
Delta Orbital Sprayer (Delta Industries, King of
Prussia, PA) or aerosol can in which the product
was purchased. Application distance between the
sprayer nozzle was 15 cm for all of the treatments.
The amount of each product delivered by the sprayer
varied based on the formulation but complete
coverage was achieved in every instance. Orange
Guard was delivered in the amount of 1.8 mL/
replicate, CedarCide 2.2 mL/replicate, Essentria
Broadcast Aerosol 0.9 mL/replicate, EcoSmart Home
Pest Control 1.6 mL/replicate, Natria Home Pest
Control 1.7 mL/replicate, RestAsure 0.84 mL/replicate,
Cirkil 1.3 1.3 mL/replicate, CimeXa 0.1 g/replicate, D-
Force Aerosol 0.7 mL/replicate, Bonide Bedbug Killer
2.4 mL/replicate, and the control was comprised of
1.6 mL of water. Five minutes after treatment, the
insects in each cup were moved on to a 9.4-cm-diam,
1.5 cm deep plastic dish (Greiner Bio-One North
America, Monroe, NC) with a 7.5-cm-diam #2
Whatman (VWR, Westchester, PA) filter paper disc
inside as harborage and the dish was covered with a
flat lid. This procedure was replicated five times for
each of the 11 treatments, and the treatments were
arranged in a completely randomized experimental
design.
Knockdown (the inability of the bed bug to right
itself or move in an upright deliberate manner) and
recovery (process leading to restoration from
knockdown) were determined by counting numbers
of knocked down insects in each cup at 5, 15, 30, 45,
60, 120, and 240 min after treatment. Mortality (no
movement on being probed) was assessed as
numbers of dead insects at 1, 2, 3, and 4 days
following treatment.
The knockdown, recovery, and mortality assays
were each analyzed using one-way ANOVA and using
repeated measures with treatment and time as factors
and a treatment × time interaction (Analytical
Software, 1998). Mean separations were
accomplished with Tukey’s HSD (P < 0.05)
(Analytical Software, 1998). Because normality and
homogeneity of variance assumptions were not
violated, data were not log (x + 1)-transformed before
analyses.
RESULTS
Knockdown effects were detected (F = 21.95, df
= 76, 384, P < 0.0001). Within the first 5 min
CedarCide, EcoSmart, and Bonide caused complete
knockdown and similar results were obtained with
Orange Guard, Natria, Cirkil, and D-Force (Fig. 1)
(Table 1). RestAsure and Essentria achieved 52%
and 48% knockdown, but CimeXa failed to cause
more knockdown than the negative control
throughout the assay (Fig. 1). The most potent
knockdown-inducing products at 5 min maintained
high efficacy levels for the rest of the 4-h-long
knockdown assessment, and knockdown in the
Essentria treatment increased from 48 to 92% by 15
min (Fig. 1). Although knockdown in the Natria
treatment was not statistically different from complete
knockdown, it declined from a peak of 66% at 5 min
to 60% at 15 min and to ≈52% by 30 min (Fig. 1).
Similarly, RestAsure did not statistically differ at each
sampling time from the products that were>90%
effective and knocked down only ≈60% of the
cimicids (Fig. 1). Repeated measures detected a
treatment effect (F = 24.45, df = 10, 384, P < 0.0001),a
time effect (F = 6.04, df = 6, 384, P < 0.0001) occurred
between 5 and 15 min, and a treatment × time
interaction was detected (F = 7.35, df = 60, 384, P <
2015 Donahue et al.: Effect of natural products on cimicidae 111
0.0001). Three nonconventional insecticides
achieved > 90% knockdown within 5 min, one did so
within 15 min, and Orange Guard maintained ≈78%
knockdown throughout the 4-h-long assay (Table 1).
Recovery from knockdown did not occur in the
CedarCide, Essentria, EcoSmart, and the two
pyrethroid treatments, and it did not rise above 10%
in any of the other treatments that caused
knockdown (Fig. 1). Although treatment differences
were detected (F = 2.03, df = 32, 164, P = 0.0029),
Tukey’s HSD did not identify which means were
involved. Similarly, repeated measures detected
treatment differences (F = 2.18, df = 10, 164, P =
0.0375) that were not clarified by Tukey’s HSD. Time
did not affect recovery and a treatment × time
interaction was not detected.
Treatment influenced mortality (F = 17.55, df =
43, 219, P < 0.0001) during the 4-d sampling period
after the insecticides were applied. All of the
insecticides killed more cimicids than died in the
negative control (Table 2), but only CedarCide
caused 100% mortality and it did so by the end of
the first day (Tables 1 and 2). Essentria, Cirkil,
CimeXa, Bonide, and D-Force resulted in > 90%
mortality on the first day, and EcoSmart and Orange
Guard caused 88 and 76% mortality, respectively
(Tables 1 and 2). Natria and RestAsure killed 42%
and 46% of the cimicids on the first day, and neither
of them killed more than 52% by the end of 4 day
(Table 2). Mortality in the Orange Guard treatment
increased by 18.4% during the 4 day, becoming 87.5
and 73.1% more effective than Natria and RestAsure,
respectively (Table 2). Repeated measures detected
treatment differences (F = 19.42, df = 10, 219, P <
0.0001) resulting from the relatively low mortality in
the Natria and RestAsure treatments, and in the
negative control. Time effects (F = 11.89, df = 3,
219, P < 0.0001) occurred between the second and
third day when overall mortality increased by 3.9%.
A treatment × time interaction was detected (F =
2.43, df = 30, 219, P = 0.0003).
DISCUSSION
Desirable insecticides for cimicid control in the
home, hotels, and other locations where humans are
likely to encounter them will rapidly (within minutes)
halt biting activity and, possibly more slowly,
eliminate the pest. The two goals, knockdown and
elimination, can be accomplished separately and by
different means, or at the same time using one or
more insecticide. Elimination can occur in hours,
days, or weeks depending on the scale and
complexity of the infestation, and it can be achieved
by repellency (mainly aims to completely avert biting)
or mortality. Although neurotoxic pyrethroid
insecticides (Vijverberg and van den Bercken, 1990),
such as permethrin, are known for achieving rapid
knockdown and for their lethality to C. lectularius,
resistance has become increasingly problematic
Fig. 1. Mean (± SE) C. lectularius knockdown
at time intervals to 4 h (n = 5 replicates, one-way
ANOVA, Tukey’s HSD; a-d is abcd) for A) six
nonconventional insecticides and B) two
nonconventional insecticides, two pyrethroids, and
a control comprised of water (A and B data analyzed
together but presented separately to enhance
clarity).
0
2
4
6
8
10
abc
a-d
a
a-d
a-d a-d a-d
a-d
aaa
aaa
a
a
aaa aa
eeeee
de
bcd
a-d
a-da-d
a-d
a-d
a-d
e
bcd
a-d a-d
a-d
a-d
a-d
a-d
Cirkil
CedarCide
Natria
RestAsure
CimeXa
Orange Gua rd
A. T reatmen ts
Mean no. C. Lectularius knocked down
Minutes
0
2
4
6
8
10
515 30 45 60 120 24
0
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cd
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a
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D-Force at 5, 15, 30, and
45 min are also "ab"
eeeee
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B. Treatments
Essentria
EcoSmart
Bonide
D-Force
Nega tive control
Mean no. C. Lectularius knocked down
112 Biopesticides International Vol. 11, no. 2
(Romero et al., 2007; Davies et al., 2012; Koganemaru
and Miller, 2013). When treating structures and
surfaces, effective cimicid control products should
also provide sufficient residual effects to continue
eliminating the pest over a substantial period of time
(weeks, months) following application (Hinson et al.,
2014) because cimicids are difficult to locate and
eliminate with low-residual direct sprays (Romero et
al., 2009). Commercial nonconventional insecticides
are available for purchase but few have been
compared in terms of efficacy, particularly products
with different modes of action.
The insecticides we tested contain different
active ingredients, some have different modes of
action, and a few have different active ingredients
and modes of action within the same product. Neem-
based products, such as Cirkil, often involve a variety
of bioactive compounds (e.g., salannin, salannol,
nimbinen, gedunin, and dirachtin derivatives)that can
induce a variety of insecticidal effects (e.g., growth
regulation, repellency, mortality from direct contact
and exposure to volatiles, sublethal reproductive
inhibition) against arthropods (Jones et al., 1989;
Schmutterer, 1990, 1995; Walter, 1999; Showler et al.,
2004; Greenberg et al., 2005). A commercial product
containing 70% clarified hydrophobic extract of neem
oil, however, was found to have negligible efficacy
against cimicids (Hinson et al., 2014). The strong
efficacy of neem-based Cirkil suggests that it has a
different blend of bioactive components.
RestAsure’s proprietary mixture of active
ingredients sodium laurel sulfate, sodium chloride,
and potassium sorbate are intended to repel,
desiccate, and kill, respectively. The active
ingredients have not been well established as
insecticides and potassium sorbate is best known
as an antibacterial and antifungal agent for
preserving food (Nikolov and Ganchev, 2011), and
sorbic acid was reported to have an insecticidal effect
in stored products (Dunkelet al., 1984; Dunkel and
Read, 1991).
A variety of essential oils have shown pest
control properties (Koul et al., 2008). Essentria’s 2-
phenethl propionate and two botanically-based
essential oils are indicated by the label as being an
octopamine blocker and repellent, and EcoSmart
contains 2-phenethyl propionate and four
botanically-based essential oils. The precise modes
of action of the various essential oils are not always
clear, but most essential oils are neurotoxic, involving
Table 1. Mean (± SE) peak percentage knockdown and mortality and time at which the peak was first
observed
TreatmentaKnockdown (%) Minutes Mortality (%) Hours
Orange Guard 82.0 ± 11.9 15 72.0 ± 16.2 96
CedarCide 100 5 100 24
Essentria 92.0 ± 5.8 15 94.0 ± 6.0 24
EcoSmart 100 5 96.0 ± 2.2 72
Natria 66.0 ±15.1 5 42.0 ± 12.8 24
RestAsure 60.0 ±15.1 15 56.0 ± 16.3 72
Cirkil 98.0 ±2.0 5 98.0 ± 2.0 24
CimeXa 34.0 ± 8.7 240 98.0 ± 2.0 24
Bonide 100 5 78.0 ± 17.4 24
D-Force 98.0 ±2.0 5 98.0 ± 2.0 24
Control 0 n/a 0 n/a
aOrange Guard, a.i.,d-limonene (5.8%); Natria Home Pest Control a.i., soy bean oil and eugenol (0.25%); RestAsure
a.i., sodium laurel sulfate, sodium chloride, and potassium sorbate (proprietary mixture); CedarCide a.i., cedar oil (5-
20%) and hydrated silica (80-95%); Essentria Broadcast Insecticide a.i., 2-phenethyl propionate (3%), rosemary oil
(1.5%), and peppermint oil (2%); EcoSmart Organic Home Pest Control a.i., 2-phenethyl propionate (2%), clove oil
(1%), rosemary oil (1%), peppermint oil (1%), and thyme oil (0.5%); Cirkil a.i.,neem oil (5.5% cold pressed neem oil);
CimeXa a.i., silica gel (100%); Bonide Bedbug Killer a.i., permethrin (0.5%) positive control; D-Force a.i., deltamethrin
(0.6%) positive control; water, negative control.
2015 Donahue et al.: Effect of natural products on cimicidae 113
acetylcholinesterase inhibition, competitive
obstruction of octopaminergic receptors, or
interference with GABA-gated chloride channels
(Mann and Kaufamn, 2012). Eugenol, from cloves
and other botanical sources, in Natria acts on
octopaminergic receptors (Khanikor et al., 2013) and
it has repellent knockdown and lethal effects on a
variety of herbivorous and phlebotomous arthropods
(Bhatnagaret al., 1993, Cornelius et al., 1997, Lee et
al., 1997, Obeng-Ofori and Reichmuth, 1997; Isman,
2000; Hummelbrunner and Isman, 2001; Thorsell et
al., 2006; Hieuet al., 2010; Velazquez et al., 2011b).
Peppermint, another essential oil, is mainly used in
arthropod control as a repellent (Thorsell et al., 2006;
Mkolo et al., 2011; Hieu et al., 2012), and rosemary
has been reported as being toxic to arthropods
(Velazquez et al., 2011a). Orange Guard’s d-limonene,
from citrus oil, destroys the wax coating of arthropod
respiratory systems and has been shown to kill a
variety of arthropods and to inhibit egg hatching in
some, including ticks (Coates et al., 1991; Lee et al.,
1997; Hummelbrunner and Isman, 2001; Raina et al.,
2007; Ferrarini et al., 2008). A commercial cimicid
control product with active ingredients clove oil,
peppermint oil, and sodium lauryl sulfate produced
100% cimicid mortality in 7–14 days depending on
the insect strain (Hinson et al. 2014). Another
commercial product with geraniol, cedar oil, and
sodium lauryl sulfate caused 92.5% cimicid control
in apartment buildings (Wang et al., 2014). A
different commercial product with phenethyl
propionate, soybean oil, and clove oil only provided
45% control in a chicken house (Goddard and
Mascheck, 2015). Cedar oil in CedarCide blocks
respiration and has neurological effects, including
toxicity and repellency (Panella et al., 1997; Dolan et
al., 2007), and some other essential oils, if delivered
in sufficient doses, can in the same way affect
respiration. Another commercial product containing
10% cedar oil, also provided 100% cimicid mortality,
within 1 h (Hinson et al., 2014). Soybean oil in Natria,
like most oils on arthropods, can also block
respiration (Bográn et al., 2006).
CimeXa, a dust formulation, destroys the waxy
Table 2.Mean (± SE) numbers of C. lectularius killed by contact (spray) application of eight natural product-
based and two pyrethroid insecticides after 1–4 days
Treatmenta Mortalityb
Days post treatment
123 4
Orange Guard 7.6 ± 1.2a-e 8.0 ± 1.0a-e 8.2 ± 0.9a-e 9.0 ± 0.5a-c
CedarCide 10a 10a 10a 10a
Essentria 9.4 ± 0.6a,b 9.4 ± 0.6a,b 9.4 ± 0.6a,b 9.4 ± 0.6a,b
EcoSmart 8.2 ± 0.4a-d 8.8 ± 0.4a-d 9.6 ± 0.2a,b 9.6 ± 0.2a,b
Natria 4.2 ± 1.3e,f 4.2 ± 1.3e,f 4.6 ± 1.2e 4.8 ± 1.4e,f
RestAsure 4.6 ± 0.6e 4.8 ± 1.5d,e 5.6 ± 1.6b-e 5.2 ± 1.6c-e
Cirkil 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a
CimeXia 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a
Bonide 9.6 ± 0.4a,b 9.4 ±0.4a,b 9.4 ± 0.4a,b 9.4 ± 0.4a,b
D-Force 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a 9.8 ± 0.2a
Control 0g 0g 0.4 ± 0.4fg 0.4 ± 0.4fg
aOrange Guard, a.i., d-limonene (5.8%); Natria Home Pest Control a.i., soy bean oil and eugenol (0.25%); RestAsure
a.i., sodium laurel sulfate, sodium chloride, and potassium sorbate (proprietary mixture); CedarCide a.i., cedar oil (5-
20%) and hydrated silica (80-95%); Essentria Broadcast Insecticide a.i., 2-phenethyl propionate (3%), rosemary oil
(1.5%), and peppermint oil (2%); EcoSmart Organic Home Pest Control a.i., 2-phenethyl propionate (2%), clove oil
(1%), rosemary oil (1%), peppermint oil (1%), and thyme oil (0.5%); Cirkil a.i.,neem oil (5.5% cold pressed neem oil);
CimeXa a.i., silica gel (100%); Bonide Bedbug Killer a.i., permethrin (0.5%) positive control; D-Force a.i., deltamethrin
(0.6%) positive control; water, negative control.
bValues followed by different letters are significantly different (P < 0.05), one-way ANOVA, Tukeys HSD.
114 Biopesticides International Vol. 11, no. 2
cuticle of the cimicid, resulting in dehydration
(Akhtar and Isman, 2013; Goddard and Maschek,
2015). Although cimicid control in a chicken house
reached only 46% when diatomaceous earth mixed
with the neonicotinoid insecticide dinotefuran was
used, CimeXa provided 100% control within 24 h
(Goddard and Mascheck, 2015). Because effective
dust-based desiccant products are not affected by
residue aging, Anderson and Cowles (2012)
concluded that they were superior to sprayable
pyrethroid products for cimicid control.
We found that Cirkil, CedarCide, Orange Guard,
Essentria, EcoSmart were as effective or nearly as
effective as the two pyrethroids, Bonide and D-Force,
in terms of achieving > 80% knockdown within 15
min and maintaining that level for the 2-h duration
of the knockdown assay. The same five
nonconventional insecticides achieved > 90% cimicid
mortality within 4 days, hence, all five were as
effective for knockdown and elimination as the
pyrethroid positive controls. The five
nonconventional products involved neem oil, cedar
oil, d-limonene, 2-phenethyl propionate, rosemary oil,
peppermint oil, clove oil, and thyme oil. Hence,
certain essential oils, neem constituents, and 2-
phenethyl propionate, which have a variety of modes
of action (e.g., octopamine receptor inhibition,
possibly other neurotoxic effects, and respiratory
interference or blockage can induce rapid knockdown
and relatively high mortality within days). Natria’s
and RestAsure’s moderate knockdown (50–60% with
relatively great variability) and 40–50% lethality
indicates that the eugenol, soybean oil, sodium lauryl
sulfate, sodium chloride, and potassium sorbate were
not sufficient for adequate knockdown and mortality
at the dosages and in the formulations used.
Repeated measures showed that in terms of
knockdown, Natria and RestAsure averaged 32 to
42.5% less, and mortality averaged 46.3 to 50% less,
than the more efficacious conventional and
nonconventional products, and that knockdown for
most products occurred within the first 15 min. While
CimeXa only caused negligible knockdown, it was
highly effective for killing bedbugs within 24 h.
Similarly, repeated measures showed that mortality
mainly occurred within 24 h and that there was a
slight (4%) average increase between the second and
third post-treatment days. Within the parameters of
our study, Cirkil, CedarCide, Orange Guard, Essentria,
and EcoSmart were best for rapid knockdown and
elimination, but CimeXa provided effective control
in one day absent rapid knockdown.CimeXa, and
other similarly effective dust-based products, might
gain a rapid knockdown effect by combining it with
another insecticide with strong knockdown capability.
Because this study involved contact knockdown
and lethal effects within a maximum of 4 days, the
full extent of possible effects of the tested products
were not measured. Neem, for example, can contain
many bioactive compounds (Jones et al., 1989;
Schmutterer, 1990, 1995; Walter, 1999) whose effects
were not observed in the context of the study.
Azadirachtin, the most widely recognized active
ingredient of neem-based insecticidal products, is
mostly regarded as an insect growth regulator that
affects insects during molts or other transitions in
developmental stages (Schmutterer, 1990, 1995;
Kraiss and Cullen, 2008), hence, Cirkil might not have
shown its full potential for eliminating cimicids.
Residual effects from contact with treated surfaces
were also not measured, nor was the contribution of
repellency to control, and horizontal transmission of
powder and botanical-based nonconventional
insecticides at aggregations has been shown to occur
in cimicids (Akhtar and Isman, 2013). Finally,
sublethal effects that might hinder reproduction (e.g.,
reduce fecundity, decrease egg hatch from treated
parent insects) were not considered. Some factors
that might have negatively influenced efficacy under
natural conditions were also not tested. As examples,
aggregation can reduce mortality from some
insecticides (Benoit et al., 2007), and long-term
effects of population dynamics can rekindle and
reintroduce problematic infestations (e.g.,
infestations can originate from a single mated female)
(Booth et al., 2012; Hinson et al., 2014).
The nonconventional products Orange Guard,
CedarCide, Essentria, EcoSmart, and Cirkil, displayed
the knockdown and elimination capabilities of a
desirable cimicid insecticide when applied as direct
contact sprays. Based on the active ingredients of
each product, d-limonene, cedar oil, and cold pressed
2015 Donahue et al.: Effect of natural products on cimicidae 115
neem oil were each effective. Because Essentria and
EcoSmart are blends of essential oils and specific
bioactive chemicals, the relative contributions of 2-
phenethyl propionate, rosemary oil, peppermint oil,
clove oil, and thyme oil to knockdown and mortality
were not established. A sixth nonconventional
product, CimeXa, comprised of silica gel, was
effective at eliminating the pest within a single day.
It is possible that the multiple modes of action of
most of the nonconventional products we tested,
some sufficiently benign to be exempt from EPA
registration, will delay or prevent the development
of resistance commonly associated with conventional
insecticides.
Acknowledgments. We thank Alameda County
Vector Control Services District, Department of
Environmental Health for financial assistance, and
Blake Wilson for critical review of an earlier draft.
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Accepted 2 December 2015