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All content in this area was uploaded by Roberto M Pereira
Content may be subject to copyright.
HOUSEHOLD AND STRUCTURAL INSECTS
Lethal Effects of Heat and Use of Localized Heat Treatment for
Control of Bed Bug Infestations
ROBERTO M. PEREIRA,
1
PHILIP G. KOEHLER, MARGIE PFIESTER, AND WAYNE WALKER
Department of Entomology, University of Florida, Building 970 Natural Area Drive, Gainesville, FL 32611-0620
J. Econ. Entomol. 102(3): 1182Ð1188 (2009)
ABSTRACT Bed bugs, Cimex lectularius L., hide in cracks and crevices in furniture and are difÞcult
to control. The bed bug thermal death kinetics were examined to develop a heat treatment method
to eliminate bed bug infestations in room contents. High temperatures caused temporary immobili-
zation (knockdown) of bed bugs even with exposures that did not have lethal effects. Exposure of bed
bug adults to 39!C for 240 min caused no mortality; however, as temperatures increased from 41 to
49!C, exposure times that caused 100% mortality decreased. The temperature difference to provide
a 10-fold change in the mortality was estimated at 4!C, and the estimated activation energy (E
A
) was
between 484 and 488.3 kJ/mol. This demonstrates that bed bugs are not more resistant or susceptible
to changes in temperature than other tested insects and that the temperatures needed to kill bed bugs
are relatively low. In room treatment tests, heat treatment times varied from 2 to 7 h with complete
mortality of exposed bed bugs within the treatment envelope created by surrounding the treated
furniture with polystyrene sheathing boards. Containment and circulation of heat around the
treated material were crucial factors in an efÞcient heat treatment for bed bug control. The room
ßoor material greatly affected containment of the heat. The tested method for limited heat
treatment of furniture and other room contents required equipment costing less than US$400 and
provided opportunity for residual pesticide application around the room with minimal disruption
in use of treated room.
KEY WORDS Cimex lectularius, heat treatment, control, lethal temperature, bed bug
Bed bugs, Cimex lectularius L., have been associated
with humans for at least the past 3,500 yr (Panagio-
takopulu and Buckland 1999). After a decline in bed
bug populations in developed countries after World
War II (Kruger 2000, Gangloff-Kaufman and Schultz
2003), a resurgence of these blood-sucking insects
have been causing increasing problems (Pinto et al.
2007). Because these insects hide in cracks and crev-
ices (Usinger 1966), detection (Cooper and Harlan
2004), and control can be challenging. This is espe-
cially true when bed bug aggregations occur on beds,
furniture, and other objects where the application of
chemical pesticides may cause problems, both for the
pest control industry and for customers not willing to
accept close contact with pesticides. A physical con-
trol method applied to the room contents would be
useful as a tool in the overall management of bed bug
infestations as a supplement to crack and crevice in-
secticidal applications to potential harborages.
Heat treatment of a whole room or building is cur-
rently used for control of bed bugs (Kells 2006, Pinto
et al. 2007) as well as many other insects especially
storage pests (Tang et al. 2007). Temperatures be-
tween 44 and 45!C (Doggett et al. 2006) have been
cited repeatedly as lethal to bed bugs. However, re-
examination of the bed bug thermal death require-
ments using new methods (Gazit et al. 2004, Johnson
et al. 2004) is warranted. Besides the direct effect on
the bed bugs, sublethal high temperatures can be
detrimental to bed bug symbionts, and consequently
prevent bed bug reproduction (Chang 1974).
Heat treatments varying from whole-structure to
whole-room to containerized treatments have been
used by the pest control industry (Pinto et al. 2007),
reportedly with positive results. However, the use of
solar radiation as a heat source to kill bed bugs in
encased mattresses reportedly did not provide control
(Doggett et al. 2006) because the insects were able to
move away from high temperature areas. Cost of the
necessary equipment, the energy requirements,
treatment duration, and other difÞculties related to
commercially available whole room and building
heat treatments have motivated the examination of
alternative localized heat treatment for control of
bed bugs infestations. The objectives of these stud-
ies were to examine the bed bug thermal death
kinetics and apply results to the development of
heat treatment as a tool to eliminate bed bug infes-
tations in room contents.
1
Corresponding author, e-mail: rpereira@uß.edu.
0022-0493/09/1182Ð1188$04.00/0 !2009 Entomological Society of America
Materials and Methods
Bed Bugs. ICR and Harlan strains of the common
bed bug were reared at the University of FloridaÕs
Department of Entomology and Nematology (Gaines-
ville, FL). The insects were maintained in 240-ml glass
rearing jars (Ball Collection Elite, Jarden Home
Brands, Muncie, IN) lined on the bottom with a
90-mm Þlter paper circle (Whatman no. 1), with har-
borages made from cardboard (90 by 60 mm) folded
in a fan-like manner. To prevent insect escape, nylon
mesh with 90-
!
m opening was placed over the mouth
of the rearing jar and secured by a screw-on lid. Bed
bugs were maintained at 23Ð24!C, "50% RH, and a
photoperiod of 12:12 (L:D) h, and they were fed to
engorgement once a week on chicken hosts. Adult bed
bugs were used in the experiments because they can
be easily manipulated without causing harm to the
insects, although eggs may be more resistant (within
1!C) to the effects of high temperatures (Drenski
1928; Mellanby 1935, cited by Johnson 1941). Bed bug
colony maintenance is performed under UF/IACUC
approval E876.
Lethal Thermal Dose Determination. Polystyrene
board was cut to Þt inside an analog-controlled tem-
perature water bath (Isotemp model 205, Thermo
Fisher ScientiÞc, Waltham, MA). Ten circular holes
("1.5 cm in diameter) were cut into the polystyrene
board to allow Kimax glass test tubes (20 o.d. by 150
mm, Thermo Fisher ScientiÞc) to Þt securely, thus
allowing about two thirds of each test tube to be
immersed in the water. While the water bath was
heating, adult bed bugs were separated from the col-
onies with feather-tipped forceps. Two bed bugs were
placed in each 1.5-ml plastic microcentrifuge G-Tubes
(Thermo Fisher ScientiÞc). When the water bath
reached the desired temperature, bed bugs were
quickly transferred fromthe microcentrifuge G-Tubes
to the immersed glass test tubes. The water-bath was
heated to 39, 41, 43, 45, 47, and 49!C. Bed bugs were
held at each temperature for varying lengths of time
between 0.5 and 240 min depending on the temper-
ature, so that a series of four to Þve treatment lengths
causing 0Ð100% mortality at each temperature could
be obtained. Between 114 and 198 insects were tested
for each temperature except for 49!C at which only 24
insects were tested at two treatment durations (0.5
and 1 min). Tubes were removed from the water bath
at the designated time and bed bugs were transferred
to plastic snap-cap vials containing Þlter paper as har-
borage. Knockdown was recorded immediately, and
Þnalmortalitycounts wererecorded24 h later. Atleast
12 insects were used for each temperature/treatment
duration combination.
Methods described for determination of thermal
death kinetics (Gazit et al. 2004; Johnson et al. 2003,
2004; Wang et al. 2002a,b) were used to determine the
effect of different temperatures on bed bugs. Bed bug
survival at each test temperature was plotted against
exposure times, so that survival curves were obtained.
A thermal death curve was obtained by plotting the
observed minimum time in minutes [log (time) plot-
ted on y-axis] needed to obtain 100% bed bug mor-
tality at the different exposure temperatures (x-axis).
The duration of treatment at different temperatures
needed to kill bed bug adults was calculated and used
to estimate length of heat treatments to be used in
rooms as described below.
Heat Treatment of Rooms: Insects. Bed bugs were
separated with feather-tipped forceps into glass vials
(15 ml; Thermo Fisher ScientiÞc) also covered with
nylon mesh fabric that allowed quick penetration of
heated air into vial during heat experiments. Five to 10
live, mixed sex, adult bed bugs were placed in each
vial, and three to four vials were placed in different
locations among the room furniture to allow estima-
tion of heat penetration and bed bug mortality. Be-
cause a successful room treatment would require in-
sect elimination, we did not try to measure differences
in bed bug mortality, which would require large num-
bers of insects. Bed bug mortality was calculated on a
per-vial basis; a vial was considered live if at least one
bed bug survived, or dead if all insects were killed
during treatment. A control vial was maintained in a
closet or shelf in the treatment room, away from the
heat. Complete survival of bed bugs in control vials
was observed in all trials.
Heat Treatment of Rooms: Equipment. Equipment
used in the different heat treatment experiments in-
cluded oil-Þlled electrical space heaters (model HO-
2018, Pelonis Appliances Inc., Grand Prairie, TX; or
model EW6507L, DeLonghi, Shelton, CT); box fans
(50.8 cm in diameter, Lasko, West Chester, PA); small
desktop fans, tape, electrical extension cord, polysty-
rene sheathing board insulation (122 by 224 by 5 cm,
Perma “R”, Grenada, MS); 6-mil translucent plastic
tarp; and blankets. Temperature monitoring equip-
ment included: outdoor/indoorconsumer digitalther-
mometers (Acu-rite, Chaney Instrum. Co., Lake Ge-
neva, WI), temperature recorders (Onset Computer
Corporation, Pocasset, MA), and thermocouple
probes (model EMTSS-062G-6, Omega Engineering,
Stamford, CT) connected to laptop computer running
Tracer Daq data acquisition software (Measurement
Computing Corp., Norton, MA).
Experimental Rooms. Rooms used in the experi-
ments were all in Gainesville, FL. The room furniture
was grouped at the center of the room. Oil-Þlled heat-
ers were placed on the ßoor around the furniture and
box fans positioned so that air would blow through the
radiator of the heaters. Small desk fans were placed on
top of the furniture to assist with the air circulation
around the treated furniture. A treatment chamber
was created around the furniture either with a 6-mil
translucent plastic tarp (room D only) or polystyrene
sheathing board insulation (all other rooms). Rooms
used in the experiments, their contents, and position-
ing of room contents were as described below.
A bedroom (4.0 by 3.4 m) in an unoccupied one-
bedroom apartment in family housing complex at the
University of Florida (room D) had a vinyl tile ßoor
over concrete slab, a double bed with bed frame, box
spring, mattress, and a headboard, two dressers, a
two-seat upholstered sofa and an upholstered chair. A
June 2009 PEREIRA ET AL.: HEAT TREATMENT FOR BED BUG CONTROL 1183
6-mil plastic tarp was used to create the treatment
chamber. For the second trial in this room, four heat-
ers were used. Furniture blankets were use to better
contain the heat around the furniture. A bedroom (3.8
by 3.5 m) in an occupied two-bedroom apartment at
a commercial rental complex (room M) had a car-
peted ßoor and contained a queen-size box bed with
bed frame, box spring, and mattress, a large television
and TV stand, a small two-door cabinet, and a ßoor
lamp. Two unoccupied duplex rooms (each "17.7 m
2
)
on the second ßoor in dormitory building at the Uni-
versity of Florida (rooms Ya and Yb) had a vinyl tile
ßoor over concrete and each contained two college-
dorm style long twin beds, two desks and chairs, and
two dressers. The mattress-supporting frames on the
bed were raised to the highest possible position so that
dressers, desks and chairs could Þt under the beds. A
bedroom (4.3 by 3.7 m) in an occupied two-bedroom
apartment on the second ßoor of family housing com-
plex atthe University of Florida(room G) had a carpet
ßoor and contained a queen-size box spring and mat-
tress which were raised from the ßoor with two red
clay cored bricks placed at each box spring corner, a
large television with cable box and DVD player, two
night tables, desktop computer, several plastic bags
with clothing, and other belongings.
Except for the bedroom in a two-bedroom apart-
ment in University of Florida family housing complex,
which had a minimal bedbug infestation despite pre-
vious application of residual pesticides to the perim-
eter wall/ßoor junction area, and the mattress and box
spring used in the college dorm rooms, all other rooms
were not infested with bed bugs.
Data Collection. Temperatures were monitored at
various locations within the treated furniture, and at
locations where vials with live bedbugs were placed.
Temperature probes and recorders were wrapped in
blankets and placed inside dresser and desk drawers
and other locations to simulate conditions expected to
have the slowest temperature increase. Treatments
were terminated when the monitoring temperature
probes from all locations were above the expected
lethal temperature for bed bugs (45!C). At that time,
the insulating box or cover was removed, and all tem-
perature probes and recorders were recovered along
with any bed bug vials. Vials were labeled appropri-
ately and mortality of bedbugs was evaluated imme-
diately and conÞrmed in close observation in the lab-
oratory. After the end of trial two in the dorm rooms,
the bed bug-infested mattress and box spring were
inspected for the presence of live and dead insects.
The mattress and the box spring were inspected on
external surfaces and the box springÕs bottom cover
was removed and the underside of the box spring top
was also examined thoroughly.
Results and Discussion
Lethal Thermal Dose. Bed bugs exposed to heat
suffered high levels of knockdown even at tempera-
tures that ultimately produced low mortality (Table
1). For temperatures between 43 and 49!C, 100% ini-
tial knockdown corresponded to 0Ð100% Þnal mortal-
ity, depending on the exposure time. These results
demonstrate that short exposures to temperatures
above 41!C will cause temporary immobilization of
bed bugs, even when lethal levels were not reached.
Once the bed bugsÕ exposures to high temperatures
were interrupted, some insects were able to survive.
We did not test long-term survival of the heat-exposed
bed bugs and did not determine whether survivorsÕ
Þtness was compromised. Bed bugs that survived ex-
posures to nonlethal temperatures have been shown
to have reduced Þtness (Janisch 1933, 1935, cited by
Johnson 1941). Sublethal effects of high temperatures
are documented for several insects (Neven 2000,
Mahroof et al. 2005). However, thermal wounding by
sublethal temperatures may be as deadly, but without
obvious effects that lethal temperatures cause (Den-
linger and Yocum 1998).
CoefÞcients for the n#0 kinetic order model for
the thermal mortality of bed bug adults were higher
than those for any other kinetic order (Table 2; Fig.
1); therefore, parameters for zero-order equations
were used for determination of lethal thermal doses.
Exposure of bed bug adults to 39!C for a maximum of
240 min caused no mortality in the exposed insects.
However, bed bug survival decreased with increased
length of exposure to temperatures between 41 and
49!C (Fig. 1). At 41!C, exposures of 60 min were
necessary to cause 11% mortality in bed bugs, but all
bed bugs were killed with 41!C exposures of 100 min.
At 43!C, 42% of insects were killed with 10-min ex-
posures, 75% with 20-min exposures, and no bed bugs
survived 25-min exposures. With 45!C, 2-min expo-
Table 1. Mean percentage of initial knockdown and mean
percentage of 24-h mortality (!SE) among bed bug adults exposed
to five different temperatures for varying lengths of time
Temp
(!C)
Time
a
(min)
% knockdown
b
(mean $SEM)
% mortality
c
(mean $SEM)
49 0.5 100 $0 75 $11
1 100 $0 100 $0
47 0.5 100 $00$0
1 100 $0 50 $18
1.5 100 $0 75 $11
2 100 $0 92 $8
2.5 100 $0 100 $0
45 2 100 $00$0
2.5 100 $08$8
3 100 $0 50 $13
3.5 100 $0 83 $11
43 7.5 100 $00$0
10 92 $8 42 $20
15 100 $0 42 $8
20 100 $0 75 $11
25 100 $0 100 $0
41 60 6 $6 11 $7
70 50 $18 33 $11
80 92 $8 67 $11
90 92 $8 75 $11
100 100 $0 100 $0
a
Only time/temperature combinations used in generating mortal-
ity curves in Fig. 1 are presented. n#12 for all temperature/time
combinations, except n#18 for 41!/60 min.
b
Knockdown evaluated immediately after exposure to heat.
c
Final mortality evaluated 24 h after removal from heat.
1184 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3
sures killed only 8% of the insects, but 3.5 min killed
83% of the insects, whereas only 1-min exposure to
47!C killed 50% of the adult bed bugs and all insects
were killed with exposure to 47!C for just 2.5 min. All
insects exposed to 49!C for just 1 min were killed, and
75% were killed with just 0.5-min exposure.
Although our results conÞrm that 45!C can kill bed
bug adults (several authors cited by Johnson 1941), it
is clear that exposures to these temperatures should
exceed 10 min to guarantee total mortality (Table 1;
Fig. 2). Temperatures at or above 49!C should cause
bed bug death in %1 min. Lower temperatures, be-
tween 40 and 45!C, also can be used to kill bed bugs,
but necessary exposure times increase signiÞcantly.
However, because temperatures above 39!C are lethal
to bed bug adults, as the temperature increases above
this potential threshold level, the accumulated heat
stress on the insects increases continuously. Thus,
mortality of bed bugs may occur with considerably
shorter exposures to &41!C temperatures than those
estimated from our experiments.
The thermal death curve (Fig. 2) was similar to
curveobtained using predicted timesfor 99.997%mor-
tality generated by the zero-order model (graph not
shown). The values for z (the temperature difference
to provide a 10-fold change in the mortality) were
estimated at 4!C from the thermal death curve, and at
3.97 from the zero-order model. The estimated acti-
vation energy (E
A
) was 484.4 and 488.3 kJ/mol from
the thermal death curve and the zero-order model,
respectively. Both z and E
A
are similar to those ob-
tained for Mediterranean fruit ßy larvae and eggs
(Gazit et al. 2004) and codling moth (Wang et al.
2002a). The activation energy for bed bugs falls near
the middle of the range for E
A
for other insects (Jang
1986;Wang et al. 2002b; Johnson et al. 2003, 2004; Tang
et al. 2007), suggesting that bed bugs are not more
resistant to changes in temperature than other insects.
Temperature increases needed to kill all bed bug
stages are probably below those that would cause
damage to furniture and other materials that may be
infested with these insects. Previous research (several
authors cited by Johnson 1941) demonstrated only a
Table 2. Coefficients of determination (r
2
) for kinetic order
(n"0, 0.5, 1, 1.5, and 2) models for thermal mortality of bed bug
adults at four temperatures
Temp (!C) 0
a
0.5 1 1.5 2
41 0.976 0.975 0.935 0.911 0.908
43 0.913 0.861 0.758 0.705 0.697
45 0.946 0.914 0.841 0.794 0.787
47 0.902 0.952 0.981 0.986 0.987
Mean 0.934 0.925 0.879 0.849 0.845
Models used were ln(survival) #'kt (c, for kinetic order (n) #
1; (survival)
1'n
#'kt (c,for n )1. Bed bug survival wasregressed
against exposure time (minutes) at each temperature (Celsius), and
values for k and c were obtained from regression curves (Gazit et al.
2004).
a
The zero-order model was selected for estimation of mortality
curves of bed bug adults exposed to different temperatures due to
greater and moreconsistentcoefÞcientsof determination (r
2
) values.
Fig. 1. Mortality curves for bed bug adults exposed to high temperatures (41Ð49!C) in the laboratory.
Fig. 2. Thermal death time curve obtained by plotting
the observed minimum time in minutes [log(time) plotted
on y-axis] needed to obtain 100% bed bug mortality at the
different exposure temperatures (x-axis). This curve deÞnes
the boundary of timeÐtemperature combinations that can be
expected to cause 100% mortality of bed bug adults.
June 2009 PEREIRA ET AL.: HEAT TREATMENT FOR BED BUG CONTROL 1185
minimal difference in lethal temperatures between
bed bug eggs, nymphs, and adults. To simulate the
reported higher lethal temperatures required to ex-
terminate eggs (Mellanby 1935 cited by Johnson
1941), we calculated a 1!C shift to the right in the
thermal death curve (Fig. 2). For a Þxed exposure
temperature, the exposure required for total mortality
of heat-resistantlife stages increased by"80% for each
1!C increase in lethal temperature. Although doubling
the exposure time represents signiÞcant increase at
low temperatures, for temperatures "45!C, for which
the exposures times are very short (%10 min), these
increases are insigniÞcant for practical applications.
Heat Treatment of Rooms. Among all heat-treat-
ment trials, those in rooms with carpeted ßoors pro-
duced lethal temperatures for the bed bugs in the
shortest times (2.4Ð3.1 h), compared with treatment
times between 4.9 and 7.3 h for rooms with tile ßoors
(Table 3). Temperatures at different locations within
the treatment envelope (Fig. 3) varied depending on
the position of the heaters and fans, amount of furni-
ture and other materials within the envelope being
heat-treated, and level of insulation between the tem-
perature monitor and the heated air inside the treat-
ment envelope. The difference between the lowest
and the highest maximum temperatures measured in
each room trial varied from &4 to %23!C. Highest
temperatures were always measured at unprotected
locations exposed to the heated air in the treatment
envelope. Lowest temperatures were observed when
temperature monitors were placed inside drawers or
other insulated locations, especially when wrapped in
blankets that added insulation from the high air tem-
perature in the treatment envelope.
The heating rates for different locations followed
trends that also depended on the degree of insulation
between the heaters and heated air in the treatment
envelope and the temperature-monitoring device.
Temperatures at exposed locations tended to increase
rapidly in the initial phase of the heat treatment but
tended to stabilize toward the Þnal phase of the treat-
ment. In contrast, temperatures in locations insulated
from the heated air rose very slowly in the beginning
of the treatment, but then reached a higher rate of
increase toward the end of the heat treatment. Tem-
peratures atthese insulated locations continuedto rise
even after the heaters had been disconnected, espe-
cially when the treatment envelope was maintained
intact.
Despite generating temperatures well above the
lethal levels for bed bugs (41Ð49!C) within the treat-
ment envelope, the heat treatment did not elevate the
Table 3. Heat treatment parameters and observed tempera-
tures (mean and range) in rooms with tile or carpet floor during
localized heat treatment of room contents
Floor type
Tile Carpet
Trials 8 3
Heaters 2 or 4
a
2
Insulation Various
b
Styrofoam boards
Treatment duration (h) 5.7 (4.9Ð7.3) 2.6 (2.4Ð3.1)
Room temp. start (!C)
c
24.0 (21.0Ð26.6) 25.6 (22.9Ð25.6)
Room temp. max. (!C) 28.3 (27.7Ð29.4) 29.2 (26.7Ð31.7
c
)
Lowest max. temp. (!C)
d
44.7 (37.9Ð51.8) 46.8 (44.1Ð51.8)
Highest max. temp. (!C)
d
58.0 (41.5Ð67.4) 59.6 (55.4Ð62.5)
% bed bug mortality
e
83.4 (0.0
f
Ð100) 100 (100Ð100)
a
Four heaters used in second trial only.
b
Initial trial, plastic tarp; second trial, tarp (blankets; other trials,
Styrofoam boards.
c
Roomtemperatureat startof treatmentand max duringtreatment.
Room temp not recorded for every trial.
d
Lowest or highest maximal temperature among the all location
within the treatment envelope for each trial.
e
Calculated on a per-vial basis (three bed bug vials per trial each
with Þve or 10 adult bed bugs) so that each vial was considered live
if at least one bedbug survived,or dead if allinsects werekilled during
treatment.
f
Some dead bed bugs in vial placed between mattress and box
spring where highest max was recorded.
Fig. 3. Temperature at different locations within the heat-treated furniture during trial 2 in room Yb.
1186 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3
room temperature to temperatures &32!C (Table 3).
Maintaining the room temperature at comfortable lev-
els for human activity is very important because the
heat treatment is intended to supplement a residual
pesticide applied to the baseboard and other potential
resting areas for bed bugs. Such treatment could be
applied while the room furniture is exposed to heat
treatment.
The bed bugs placed in different locations during
the treatments had 100% mortalityfor all but two trials:
the Þrst trial (room D) and the initial trial in room Yb,
both in rooms with tile ßoors. The initial treatment
trial never produced lethal temperatures for the bed
bugs in any location where temperature was mea-
sured. The maximum temperature reached was 41.5!C
after 6.3 h, and the total treatment period was 7.3 h,
indicating that the temperature in the treatment en-
velope did not rise during the last hour. This stabili-
zation of the temperature was due to the excessive
heat loss through the plastic tarp and the tile ßoor.
Once polystyrene sheathing boards were used as the
insulation around the treated furniture, the heat loss
was signiÞcantly reducedand temperaturescontinued
to increase throughout the treatments.
The only other instance of bed bugs not dying dur-
ing treatments (one vial in trial one in room Yb)
occurred when bed bug vials were wrapped in blan-
kets and placed inside a chest drawer far from the
heaters. Because temperature at this location was not
monitored from outside of the treatment envelope,
heat application was interrupted, based on tempera-
turesat other monitored locations where they reached
the desirable level. However this occurred before the
temperature of the bed bug vial could reach lethal
levels. Discrepancies between the temperatures at
monitored locations and this one were because of
greater insulation provided by blanket wrapping and
poor distribution of temperatures in the treatment
envelope. This occurred because both heaters were
placed on one side of the insulating box and heated air
was not distributed uniformly. These results demon-
strate the need to place heaters at opposite corners of
the treatment envelope and place fans so that circu-
lation of heated air is maximized.
Our results from heat treatments in rooms also shed
some light on results of solar-heat treatment of en-
cased mattresses (Doggett et al. 2006). The effects of
both heat loss to the ground or faulty insulation of
treatment envelope, as well as the demonstrated need
for good circulation of the heated air, were probably
factors that caused the ensolarization of the encased
mattress not to produce uniformly lethal tempera-
tures.
Containment and circulation of heat around the
treated material are crucial factors in an efÞcient heat
treatment for bed bug control. The containment pro-
vided by the polystyrene sheathing board insulation
was sufÞcient to prevent excessive heat loss from the
treatment envelope and prevent excessive heating of
the surrounding room. Because the heat was con-
tained and circulated efÞciently, the air space around
the treated furniture increased rapidly. This rapid in-
crease of temperature from outside would likely cause
bed bugs to move further inside the furniture, moving
away from rising temperatures (Doggett et al. 2006).
The rapid increase of temperature is also likely to
quickly immobilize the bed bugs as observed during
our laboratory studies. Also, rapid increase in temper-
atureallows treatmentto be completed in a short time,
well below the 16 h required for whole-room treat-
ments (Getty et al. 2008). Long treatment times cause
major disruption in use of the treated structure, re-
quire greater energy input, and prevent simultaneous
application of residual pesticides.
The process described herein provides a method for
heat treatment of furniture and other room contents,
while providing opportunity for residual pesticide ap-
plication around the room. Total cost for heaters, fans,
insulation, temperature monitoring equipment, and
other miscellaneous materials used was approximately
US$300. Because of the relatively low temperatures
required for bed bug elimination, limited heat treat-
ments of room contents using low cost equipment can
be accomplished in %6 h. This would allow use of this
method in combination with other bed bug control
methods with minimal disruption in use of the treated
room.
Acknowledgments
We thank Eric Lee (University of Florida Department of
Housing & ResidenceEducation), JoshGibson, andthe other
members at the University of Florida Urban Entomology
Laboratory for technical assistance with bed bug colonies
and experiments.
References Cited
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Received 1 December 2008; accepted 18 February 2009.
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