2013 Khodayari et al Environ Entomol .pdf
Original filename: 2013 Khodayari et al Environ Entomol.pdf
This PDF 1.4 document has been generated by / iText 2.1.5 (by lowagie.com), and has been sent on pdf-archive.com on 07/07/2015 at 22:33, from IP address 93.182.x.x.
The current document download page has been viewed 713 times.
File size: 295 KB (8 pages).
Privacy: public file
Download original PDF file
Seasonal Changes in the Cold Hardiness of the Two-Spotted
Spider Mite Females (Acari: Tetranychidae)
Author(s): S. Khodayari , H. Colinet , S. Moharramipour , and D. Renault
Source: Environmental Entomology, 42(6):1415-1421. 2013.
Published By: Entomological Society of America
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the
biological, ecological, and environmental sciences. BioOne provides a sustainable online
platform for over 170 journals and books published by nonprofit societies, associations,
museums, institutions, and presses.
Your use of this PDF, the BioOne Web site, and all posted and associated content indicates
Usage of BioOne content is strictly limited to personal, educational, and non-commercial
use. Commercial inquiries or rights and permissions requests should be directed to the
individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers,
academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Seasonal Changes in the Cold Hardiness of the Two-Spotted Spider
Mite Females (Acari: Tetranychidae)
S. KHODAYARI,1 H. COLINET,2 S. MOHARRAMIPOUR,1,3
Environ. Entomol. 42(6): 1415Ð1421 (2013); DOI: http://dx.doi.org/10.1603/EN13086
ABSTRACT The twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is an
important agricultural pest. Population dynamics and pest outbreaks highly depend on the overwintering success of the mite specimens; therefore, it is necessary to assess winter survival dynamics of
this pest. Seasonal changes in supercooling point (SCP) and acute cold tolerance (2-h exposure at ⫺5,
⫺10, ⫺15, ⫺20, ⫺23, or ⫺25⬚C) were assessed in Þeld-collected females during the winter in 2010 Ð2011
in Iran. The SCP values varied from a minimum of ⫺30.5⬚C (January 2011) to a maximum of ⫺12.6⬚C
(April 2011). SigniÞcant differences were recorded in the SCP distribution patterns between autumnand winter-sampled females, depicting the acquisition of cold hardiness over the winter. The mean
ambient air temperature was the lowest in January (4⬚C), when the females showed the highest
supercooling ability. Correlated patterns between monthly temperatures and acute cold tolerance also
were found. At ⫺20⬚C, the survival of the mites was very low (10%) when they were sampled in
October 2010; whereas it was high (97.5%) in January 2011, before decreasing to 5% in April 2011. The
present data show that T. urticae females are chill tolerant and capable of adjusting their cold tolerance
over the winter season. Acute cold tolerance (⫺15 and ⫺20⬚C) and SCP represent valuable metrics
that can be used for predicting the seasonal changes of the cold hardiness of T. urticae females.
KEY WORDS winter survival, supercooling point, lethal temperature, pest, Acari
In temperate and polar regions, arthropods may endure prolonged exposures at subzero temperatures,
which they can survive in one of two ways (Salt 1961,
Voituron et al. 2002, Denlinger and Lee 2010): First,
freeze-tolerant arthropods can withstand extracellular
ice formation by actively inducing ice nucleation at
high subzero temperatures (intracellular freezing is
lethal in arthropods; Sinclair and Renault 2010). Second, freeze-intolerant (or freeze-avoiding) arthropods cannot survive freezing. To survive in a supercooled state, freeze-intolerant species show an array
of physiological and biochemical adjustments to seasonally increase their supercooling ability, and thus
reduce freezing risks (Zachariassen 1985, Storey and
Storey 1992). In these species, the supercooling point
(SCP) corresponds to the temperature at which body
ßuids freeze, and thus represents the lowest thermal
limit that a freeze-intolerant species can handle (Bale
Even if the ecological relevance of the SCP has been
disputed (Renault et al. 2002), it can constitute a valid
metrics of the cold tolerance in some insect species
(Worland and Convey 2001, Klok et al. 2003). SCP
frequency distributions often are characterized by a
range of different patterns, from multimodal to normal
1 Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, P.O. Box 14115-336, Tehran, Iran.
´ de Rennes 1, UMR CNRS 6553 Ecobio, 263 avenue du
Gal Leclerc, 35042 Rennes, France.
3 Corresponding author, e-mail: firstname.lastname@example.org.
distributions, reßecting for instance the seasonal
changes in cold tolerance via changes in the feeding
and physiological status (for instance molting and diapause), body water hydration (cryoprotective dehydration), and cold acclimation (Sømme and Block
1982, Knight et al. 1986, Salin et al. 2000, Colinet et al.
2007, Verdu´ 2011). In addition to SCP, the critical
thermal limits and the lethal time, or the lethal temperature, for 50% of the population (Lt50 and LT50,
respectively) also represent valuable metrics that can
be used to assess the cold hardiness of arthropod
species (Bale 1987, 1993; Turnock and Fields 2005;
The twospotted spider mites, Tetranychus urticae
Koch (Acari: Tetranychidae), whose genome has recently been sequenced (Grbic et al. 2011), are distributed worldwide and represent a pest affecting a
large range of agricultural crops (van de Vrie et al.
1972, van Leeuwen et al. 2012). T. urticae overwinters
as mated females in reproductive diapause in the soil
of infested Þelds (Plant and Wilson 1985). This reproductive diapause is induced by a combination of
environmental factors, including short photoperiod,
low temperature, and unfavorable food supply (Veerman 1977, Kawakami et al. 2009, Ito et al. 2013). Diapause usually terminates in the spring in T. urticae, and
is associated with an increase of the cold hardiness of
the females (Khodayari et al. 2013). As a result of the
severe proliferation of this pest species worldwide,
most studies conducted on T. urticae so far have fo-
0046-225X/13/1415Ð1421$04.00/0 䉷 2013 Entomological Society of America
Vol. 42, no. 6
Fig. 1. Daily minimum, maximum, and average air temperatures recorded at the Chitgar agrometeorological station
(Tehran, Iran) from October 2010 to April 2011. Arrows represent the sampling dates of female T. urticae.
cused on their biological and chemical control (Lilley
and Campbell 1999, Opit et al. 2004, van Leeuwen et
al. 2010, Dermauw et al. 2012), whereas little is known
about their cold tolerance during winter periods
(Khodayari et al. 2012, 2013). Finally, the spider mites
represent some of the major arthropod crop pests, but
seasonal studies of the overwintering survival of this
species in either Þeld or greenhouse are lacking.
In the present work, we aimed at describing the
seasonal changes in the cold hardiness of the twospotted spider mite in Iran (semiarid continental climate),
where T. urticae Þrst was observed in 1954 (Davatchi
and Taghizadeh 1954). As reported previously by
Danks (2005), it is important to couple Þeld and laboratory experiments because experiments designed
without natural environmental data may lack ecological relevance. Thus, female T. urticae were Þeld-sampled at regular intervals throughout the winter period
in 2010 Ð2011, and their cold tolerance was directly
assessed by measuring their supercooling ability and
survival to acute cold stress. The current study provides the Þrst information on the cold tolerance of the
overwintering females of T. urticae from this region of
Materials and Methods
Mites. Adult females of T. urticae were hand-collected monthly in the Þeld from ornamental cabbage
Brassica oleracea L. at Tarbiat Modares University (35⬚
44⬘N, 51⬚ 10⬘E, Tehran, Iran) from October 2010 to
April 2011. The course of the temperature change (air
temperature) during the overwintering period is
shown in Fig. 1. Outdoor climatic data were obtained
from the Chitgar agrometeorological station, which is
1 km away from the sampling site. The cabbage leaves
harboring mites were placed in plastic bags, and,
within the few minutes after collection, they were
immediately transferred to the laboratory, and directly subjected to cold tolerance assays.
Supercooling Ability. The SCP of adult females was
determined by attaching the tip of a copper-constan-
tan thermocouple to the dorsal idiosoma of each adult
female with a small spot of glue. SCP was measured in
14 Ð17 individuals for each sampling date (seven sampling dates, see Fig. 1). We used a programmable
refrigerated test chamber (model MK 57, Binder
GmbH Bergstr, Tuttlingen, Germany) in combination
with temperature data logger (model 177-T4, Testo,
Lenzkirch, Germany) that transferred the data at 2-s
intervals into a computer. The data were read using
the Comsoft 3.0 software. The temperature was cooled
from outdoor temperatures to the SCP at a constant
cooling rate of 0.5⬚C/min. The SCP was recorded at
the start of the exotherm produced by the latent heat
Survival to Acute Cold Stress. The change in cold
hardiness of females over the cold season in 2010 Ð2011
was assessed by measuring survival to a range of acute
cold exposures for each sampling date. Females were
placed in a temperature controlled chamber, where
the temperature was lowered from 20⬚C to ⫺5, ⫺10,
⫺15, ⫺20, ⫺23, or ⫺25⬚C at a rate of 1⬚C/min. Four to
Þve replicates, each consisting of a pool of 10 females,
were used for each of the six endpoint temperatures.
The cooling was stopped when the desired temperature was reached, and the temperature was maintained constant over the next 2 h. Then, the temperature was raised to 20⬚C at a rate of 1⬚C/min, and all
mites were allowed to recover for 1 d at room temperature and then checked for survival. As the females
of T. urticae remain active during their reproductive
diapause, mortality was scored as the number of mites
that exhibited no movements.
Statistical Analysis. The normality of all SCP data
were Þrst checked using the ShapiroÐWilk statistic
(␣ ⫽ 0.05). In most cases, the SCP data failed to Þt
normality (P ⬍ 0.05) and sometimes tended to show
a form of bimodal distribution. Hence, analyses based
on comparison of the distributional patterns were
used because statistical tests based on mean values are
not relevant in this case (Worland et al. 2006). Thus,
KolmogorovÐSmirnov (KÐS) two-sample tests were
used to compare the SCP distributions (Worland et al.
KHODAYARI ET AL.: COLD HARDINESS OF THE TWO-SPOTTED SPIDER MITE
2006). For the acute cold tolerance, survival curves
along with their 95% conÞdence intervals (CI) for the
proportion were Þrst dressed. Then, the temperatureÐ
mortality regression equations were calculated using
binary logistic regressions to determine the lethal temperatures for 50 (LT50) and 90% (LT90) of the population and their 95 and 99% CIs (upper and lower
limits). Correlations between acute cold tolerance
data and mean monthly temperatures were checked
using Spearman tests. All statistical analyses were conducted using MINITAB Statistical Software Release 13
(MINITAB Inc., State College, PA) and SPSS version
Meteorological Data. Daily maximum, minimum,
and average air temperatures recorded from 1 October 2010 to 30 April 2011 are shown in Fig. 1. The mean
air temperature was 23.6 ⫾ 0.4⬚C in October 2010,
4.0 ⫾ 0.5⬚C in January 2011, and 15.6 ⫾ 0.6⬚C in April
2011. The total number of freezing days (number of
days below 0⬚C) was 32 d during the sampling period
(December 2010: 1 d; January 2011: 11 d; February
2011: 14 d; and March 2011: 6 d), with a minimum
temperature of ⫺6.6⬚C recorded in January 2011.
Supercooling Ability. Adult females of T. urticae
showed a marked seasonal variability in their supercooling abilities (Fig. 2). The SCP values ranged from
⫺30.5⬚C (the lowest SCP value recorded) in January
2011 to ⫺12.6⬚C (the highest SCP value recorded) in
April 2011. The distribution pattern of the SCP values
did not differ among the sampling dates during the
period OctoberÐDecember 2010 (Fig. 2; P ⬎ 0.05).
Then, the SCP distributions signiÞcantly differed between December 2010 and January 2011 (KÐS ⫽
0.6071, P ⬍ 0.01), with median SCP values of ⫺23.2 and
⫺26.3⬚C (i.e., a shift toward lower SCP values), respectively. The distribution of SCP values also differed
from February to March 2011 (KÐS ⫽ 0.4706, P ⬍
0.05). Finally, the SCP distribution in March 2011 was
signiÞcantly different from that which has been measured in April 2011 (KÐS ⫽ 0.6078, P ⬍ 0.001; i.e., a shift
toward higher SCP values; Fig. 2).
Survival to Acute Cold Stress. Adult females of T.
urticae also showed seasonal variability in their ability
to survive acute cold stress for 2 h (Fig. 3). A significant correlation was found between the survival to
exposures at ⫺15 and ⫺20⬚C for 2 h and the mean
monthly temperatures (r ⫽ ⫺0.852, P ⬍ 0.05 and r ⫽
⫺0.964, P ⬍ 0.01, respectively), whereas the other
experimental temperatures were not correlated with
the mean monthly temperatures (P ⬎ 0.05). At ⫺20⬚C,
the survival of the mites was very low (10%) in October 2010; it was very high (97.5%) in January 2011
before declining to 5% in April 2011. None of the
female T. urticae sampled in October, November, December, and April survived the 2 h-exposure at ⫺23⬚C.
Based on binary logistic regressions, LT50 and LT90
were estimated for each sampling date (Fig. 4). LT50
was signiÞcantly correlated with the mean monthly
temperatures (r ⫽ 0.929, P ⬍ 0.01), whereas no cor-
relation was observed for LT90 (r ⫽ 0.714, P ⫽ 0.088).
LT50 was the lowest in January, February, and March
2011 (ca. ⫺22.5⬚C, P ⬍ 0.01), and the highest in April
2011 (⫺11.1 ⫾ 0.4⬚C, P ⬍ 0.01). LT50 and LT90 significantly differed (P ⬍ 0.05) among the sampling dates
The current study examined the cold tolerance of
Þeld-collected T. urticae females during the winter
period in 2010 Ð2011 in Tehran, Iran. The SCP values
decreased from ca. ⫺23 to ca. ⫺26⬚C with decreasing
ambient temperature (from an average of 23⬚C in
October 2010 to 4⬚C in January 2011) and then increased. The few published studies that examined the
supercooling ability of T. urticae reported that body
ßuids of this mite freeze at ⫺18.7⬚C in overwintering
females collected from greenhouses in Norway
(Stenseth 1965). Nondiapausing females also seem to
be characterized by higher SCP values (ca. ⫺19⬚C)
than diapausing ones (ca. ⫺24⬚C) (Khodayari et al.
2012). The present SCP values measured from Þeldsampled specimens are congruent with these early
observations. These SCP values are also similar with
those reported from other oribatid mites, whose SCP
ranges from ⫺20 to ⫺30⬚C in winter-acclimated individuals (Schatz and Sømme 1981, Block and Sømme
SigniÞcant differences were recorded in the SCP
distribution between autumn- and winter-sampled females, depicting the acquisition of cold hardiness over
the winter. A mixture of nondiapausing and diapausing
mites is usually observed in autumn in the Þeld. The
relative abundance of diapausing females over nondiapausing ones increased from 38.9% in October to
97.7% in February (Klingen et al. 2008). From January
to March 2011, overwintering females, which exhibited the lowest SCP, were most likely diapausing. The
diapausing status of T. urticae females was not monitored in the present work, but it is already known that
the SCP values differ between diapausing and nondiapausing phenotypes, with diapausing specimens
freezing at lower temperatures (Khodayari et al.
2012). Mites stop feeding when entering diapause in
early winter, and this cessation of feeding may enhance supercooling abilities through the evacuation of
the gut and the elimination of indigenous ice nucleators (Block et al. 1978, Watanabe and Tanaka 1998,
Ramløv 2000, Colinet et al. 2007). Moreover, diapause
is usually accompanied by a range of physiological and
biochemical adjustments (Colinet et al. 2012), which
subsequently increase the cold hardiness of the organisms (Denlinger 1991, Atapour and Moharramipour 2009). The accumulation of “winter” polyols
(inositol, mannitol, and sorbitol) in overwintering females may also account for a colligative depression of
their SCP (Khodayari et al. 2013). The dramatic increase in SCP in April 2011 may be associated with
termination of diapause. In this period, a wide range
of SCP values was observed, which might reßect a
Vol. 42, no. 6
Fig. 2. Frequency distribution of the supercooling points of female T. urticae sampled in the Þeld from October 2010 to
April 2011. Median SCP values (⫾average absolute deviation) are presented for each month. Results from the two-sample
KÐS tests are indicated for each distribution comparison.
mixed population of diapausing and nondiapausing
We also monitored the seasonal change in T. urticae
cold tolerance by exposing monthly collected specimens to a range of acute cold stresses and demonstrated that the mites became cold hardy in winter. Of
note, the mortality rates of the specimens exposed at
⫺5 and ⫺10⬚C for 2 h were low and did not change
signiÞcantly among the sampling periods. The high
survival rate at these thermal conditions suggests that
the mites of this region are chill tolerant according to
BaleÕs classiÞcation (Bale 2002). This view is reinforced by the fact that female mites were even able to
survive at temperatures ranging from ⫺15 to ⫺23⬚C
that were close to their SCP values. Chill tolerant
species are characterized by extensive supercooling
abilities and a high level of cold tolerance as opposed
to chill susceptible species, which do not tolerate
exposures to subzero temperatures for prolonged periods of time (Bale 2002). The chill tolerance of T.
urticae may be considered as a component of its worldwide invasive success. Further studies should also conduct chronic cold tolerance assays because the duration of cold exposure is as important as the
temperature per se. In addition, because the genome
of T. urticae has recently been sequenced, annotated,
KHODAYARI ET AL.: COLD HARDINESS OF THE TWO-SPOTTED SPIDER MITE
Fig. 3. Survival rate (⫾95% CI for the proportion) of T. urticae females collected in the Þeld from October 2010 to April
2011 and exposed at ⫺5, ⫺10, ⫺15, ⫺20, ⫺23, or ⫺25⬚C for 2 h.
and published (Grbic et al. 2011), there is enormous
potential to use this model organism to better understand the cold hardiness of other mite species.
The seasonal variation of the cold hardiness of T.
urticae, well pictured by the SCP values over the
period October 2010 ÐApril 2011, was conÞrmed by
the survival ability of the mites exposed to acute cold
stress. During the coldest months of the year, the mites
were characterized by the lowest LT50 values. Moreover, LT50 values were highly correlated with seasonal
temperatures, and among all experimental temperatures used to assess LT50, we found that ⫺20⬚C (for
2 h) best represented the seasonal variation of the cold
hardiness of the mites. Indeed, the percentage of mites
surviving at this experimental condition varied from
⬇10% in October, November, and April to nearly 100%
during the coldest months of the year (January and
February). At ⫺25⬚C (for 2 h), a temperature that was
very close to the median SCP of the overwintering
mites, almost no survival was observed.
This study shows that T. urticae females are chill
tolerant and are able to increase their cold tolerance
toward the winter season. In addition, we found that
SCP and LT50 represent valuable metrics for the monitoring of the seasonal changes of the cold hardiness of
this pest species. Our study suggests that overwintering females of T. urticae exposed to cold and frosty
nights during the winter are unlikely to experience
substantial mortality from cold conditions alone in
Iran. Meanwhile, their overwintering success also depends on the combination of many other abiotic and
biotic variables that should be further examined, such
as the duration and frequency of cold events, loss of
homeostatic control, exhaustion of the body reserves,
body dehydration, or pathogens. We also suggest that
the survival ability of female T. urticae to chronic cold
exposure or repeated frost events should be considered in further studies. Finally, to improve the management practices and to predict pest outbreaks, we
need to characterize the overwintering strategies employed by pest species. In this context, the current
study provides valuable basic information on the cold
survival of the spider mite over the winter season.
We thank the Tarbiat Modares University (Tehran, Iran),
which funded the experiments and also the travel of S. Khodayari from Iran to France. The work in Iran was funded by
the Tarbiat Modares University grants to S. Moharramipour.
Fig. 4. LT50 and LT90 values with 95% lower and upper CIs of Þeld-collected females of T. urticae from October 2010 to
April 2011. Distinct letters among the sampling dates for LT50 and LT90 represent the statistical differences among the values
according to the 95% CI.
This research was supported by the University of Rennes one
(Action Incitative de Recherche 2012ÑCollaborations Internationales) and the Centre National de la Recherche
(CNRS). We would also like to thank the anonymous referees for their helpful comments on an earlier version of this
Atapour, M., and S. Moharramipour. 2009. Changes of cold
hardiness, supercooling capacity, and major cryoprotectants in overwintering larvae of Chilo suppressalis
(Lepidoptera: Pyralidae). Environ. Entomol. 38: 260 Ð265.
Bale, J. S. 1987. Insect cold hardiness: freezing and supercooling - An ecophysiological perspective. J. Insect
Physiol. 33: 899 Ð908.
Bale, J. S. 1993. Classes of insect cold hardiness. Funct. Ecol.
Bale, J. S. 2002. Insects and low temperatures: from molecular biology to distributions and abundance. Philos.
Trans. R. Soc. Lond. B Biol. Sci. 357: 849 Ð 862.
Block, W., and L. Sømme. 1982. Cold hardiness of terrestrial
mites at Signy Island, maritime Antarctic. Oikos 38: 157Ð
Block, W., S. R. Young, E. M. Conradi-Larsen, and L. Sømme.
1978. Cold tolerance of two Antarctic terrestrial arthropods. Experientia 34: 1166 Ð1167.
Colinet, H., P. Vernon, and T. Hance. 2007. Does thermalrelated plasticity in size and fat reserves inßuence supercooling abilities and cold-tolerance in Aphidius colemani
(Hymenoptera: Aphidiinae) mummies? J. Therm. Biol.
32: 374 Ð382.
Colinet, H., D. Renault, B. Gue´vel, and E. Com. 2012. Metabolic and proteomic proÞling of diapause in the aphid
parasitoid Praon volucre. PLoS ONE 7: e32606.
Danks, H. V. 2005. Key themes in the study of seasonal
adaptations in insects I. Patterns of cold hardiness. Appl.
Entomol. Zool. 40: 199 Ð211.
Davatchi, A., and F. Taghizadeh. 1954. Citrus pests of Iran.
Appl. Entomol. Phytopathol. 14: 1Ð 80.
Denlinger, D. L. 1991. Relationship between cold hardiness
and diapause, pp. 174 Ð198. In R. E. Lee, Jr. and D. L.
Denlinger (eds.), Insects at low temperature. Chapman
& Hall, New York.
Denlinger, D. L., and R. E. Lee. 2010. Low temperature
biology of insects, p. 390. Cambridge University Press,
Dermauw, W., N. Wybouw, S. Rombauts, B. Menten, J.
Vontas, M. Grbi, R. M. Clark, R. Feyereisen, and T. van
Leeuwen. 2012. A link between host plant adaptation
and pesticide resistance in the polyphagous spider mite
Tetranychus urticae. Proc. Natl. Acad. Sci. U.S.A. 110:
Grbic, M., T. Van Leeuven, R. M. Clark, S. Rombauts, P.
Rouze´, V. Grbic´ , E. J. Osborne, W. Dermauw, P. C. Ngoc,
F. Ortego, et al. 2011. The genome of Tetranychus urticae
reveals herbivorous pest adaptations. Nature 479: 487Ð
Ito, K., T. Fukuda, H. Hayakawa, R. Arakawa, and Y. Saito.
2013. Relationship between body colour, feeding, and
reproductive arrest under short-day development in Tetranychus pueraricola (Acari: Tetranychidae). Exp. Appl.
Acarol. 60: 471Ð 477. doi: 10.1007/s10493Ð 013-9660 Ð3
Kawakami, Y., S. G. Goto, K. Ito, and H. Numata. 2009.
Suppression of ovarian development and vitellogenin
gene expression in the adult diapause of the two-spotted
spider mite Tetranychus urticae. J. Insect Physiol. 55: 70 Ð
Vol. 42, no. 6
Khodayari, S., S. Moharramipour, K. Kamali, M. Jalali Javaran, and D. Renault. 2012. Effects of acclimation and
diapause on the thermal tolerance of the two-spotted
spider mite Tetranychus urticae. J. Therm. Biol. 37: 419 Ð
Khodayari, S., S. Moharramipour, V. Larvor, K. Hidalgo, and
D. Renault. 2013. Metabolic changes associated with
cold-hardiness in the two-spotted spider mite: effect of
acclimation and diapause. PLoS ONE 8: e54025.
Klingen, I., G. Wærsted, and K. Westrum. 2008. Overwintering and prevalence of Neozygites ﬂoridana (Zygomycetes: Neozygitaceae) in hibernating females of Tetranychus urticae (Acari: Tetranychidae) under cold
climatic conditions in strawberries. Exp. Appl. Acarol. 46:
Klok, C. J., S. L. Chown, and K. J. Gaston. 2003. The geographic ranges structure of the holly leaf-miner. III. Cold
hardiness physiology. Funct. Ecol. 17: 858 Ð 868.
Knight, J. D., J. S. Bale, F. Franks, S. F. Mathias, and J. G.
Baust. 1986. Insect cold hardiness: supercooling points
and pre-freeze mortality. Cryo Letters 7: 194 Ð203.
Lilley, R., and C.A.M. Campbell. 1999. Biological, chemical
and integrated control of two-spotted spider mite Tetranychus urticae on dwarf hops. Biocontrol Sci. Technol.
9: 467Ð 473.
Opit, G. P., J. R. Nechols, and D. C. Margolies. 2004. Biological control of twospotted spider mites, Tetranychus
urticae Koch (Acari: Tetranychidae), using Phytoseiulus
persimilis Athias-Henriot (Acari: Phytoseidae) on ivy geranium: assessment of predator release ratios. Biol. Control 29: 445Ð 452.
Plant, R. E., and L. T. Wilson. 1985. A bayesian method for
sequential sampling and forecasting in agricultural pest
management. Biometrics 4: 203Ð214.
Ramløv, H. 2000. Aspects of natural cold tolerance in ectothermic animals. Hum. Reprod. 15: 26 Ð 46.
Renault, D. 2011. Long-term after-effects of cold exposure
in adult Alphitobius diaperinus (Tenebrionidae): the
need to link survival ability with subsequent reproductive
success. Ecol. Entomol. 36: 36 Ð 42.
Renault, D., C. Salin, G. Vannier, and P. Vernon. 2002.
Survival at low temperatures in insects: what is the ecological signiÞcance of the supercooling point? Cryo Letters 23: 217Ð228.
Salin, C., D. Renault, G. Vannier, and P. Vernon. 2000. As
sexually dimorphic response in supercooling temperature, enhanced by starvation, in the lesser mealworm
Alphitobius diaperinus (Coleoptera: Tenebrionidae). J.
Therm. Biol. 25: 411Ð 418.
Salt, R. W. 1961. Principles of insect cold hardiness. Annu.
Rev. Entomol. 6: 55Ð74.
Schatz, H., and L. Sømme. 1981. Cold-hardiness of some
oribatid mites from the Alps. Cryo Letters 2: 207Ð216.
Sinclair, B., and D. Renault. 2010. Intracellular ice formation in insects: unresolved after 50 years? Comp.
Biochem. Physiol. A 155: 14 Ð18.
Sømme, L., and W. Block. 1982. Cold hardiness of Collembola at Signy Island, maritime Antarctic. Oikos 38: 168 Ð
Stenseth, C. 1965. Cold hardiness in the two-spotted spider
mite (Tetranychus urticae Koch). Entomol. Exp. Appl. 8:
Storey, K. B., and J. M. Storey. 1992. Biochemical adaptations for winter survival in insects, pp. 101Ð140. In P. L.
Steponkus (ed.), Advances in low-temperature biology.
JAI Press, London, United Kingdom.
KHODAYARI ET AL.: COLD HARDINESS OF THE TWO-SPOTTED SPIDER MITE
Turnock, W. J., and P. G. Fields. 2005. Winter climates and
cold hardiness in terrestrial insects. Eur. J. Entomol. 102:
van de Vrie, M., J. A. McMurtry, and C. B. Huffaker. 1972.
Ecology of tetranychid mites and their natural enemies:
a review. III. Biology, ecology, and pest status, and hostplant relations of tetranychids. Hilgardia 41: 343Ð 432.
van Leeuwen, T., J. Vontas, A. Tsagkarakou, W. Dermauw,
and L. Tirry. 2010. Acaricide resistance mechanisms in
the two-spotted spider mite Tetranychus urticae and other
important Acari: a review. Insect Biochem. Mol. Biol. 10:
van Leeuwen, T., W. Dermauw, M. Grbic, L. Tirry, and R.
Feyereisen. 2012. Spider mite control and resistance
management: does a genome help? Pest Manage. Sci. 69:
Veerman, A. 1977. Aspects of the induction of diapause in a
laboratory strain of the mite Tetranychus urticae. J. Insect
Physiol. 23: 703Ð711.
Verdu´ , J. R. 2011. Chill tolerance variability within and
among populations in the dung beetle Canthon humectus
hidalgoensis along an altitudinal gradient in the Mexican
semiarid high plateau. J. Arid Environ. 75: 119 Ð124.
Voituron, Y., N. Mouquet, C. deMazancourt, and J. Clobert.
2002. To freeze or not to freeze? An evolutionary perspective on the cold hardiness strategies of overwintering
ectotherms. Am. Nat. 160: 255Ð270.
Watanabe, M., and K. Tanaka. 1998. Adult diapause and
cold hardiness in Aulacophora nigripennis (Coleoptera:
Chrysomelidae). J. Insect Physiol. 44: 1103Ð1110.
Worland, M. R., and P. Convey. 2001. Rapid cold hardening
in Antarctic microarthropods. Funct. Ecol. 15: 515Ð524.
Worland, M. R., H. P. Leinaas, and S. L. Chown. 2006. Supercooling point frequency distributions in Collembola
are affected by moulting. Funct. Ecol. 20: 323Ð329.
Zachariassen, K. E. 1985. Physiology of cold tolerance in
insects. Physiol. Rev. 65: 799 Ð 832.
Received 29 March 2013; accepted 8 October 2013.