Page 31 - Volume 6, Issue 1, January 2013
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© Benaki Phytopathological Institute
1
Laboratory of Applied Zoology and Parasitology, Ari-
stotle University of Thessaloniki, GR-540 06 Thessalo-
niki, Greece
2
Laboratory of Agricultural Entomology, Department
of Entomology and Agricultural Zoology, Benaki Phy-
topathological Institute, 8 St. Delta Str., GR-145 61 Ki-
fissia (Athens), Greece
3
Laboratory of Zoology and Aquatic Entomology, De-
partment of Agriculture, Ichthyology and Aquatic En-
vironment, School of Agriculture, University of Thes-
saly, GR-382 21 Volos, Greece
* Corresponding author:
Hellenic Plant Protection Journal
6:
29-39, 2013
Fumigant toxicity of six essential oils to the immature stages
and adults of
Tribolium confusum
G. Theou
1
, D.P. Papachristos
2*
and D.C. Stamopoulos
3
Summary
Six essential oils derived from
Lavandula hybrida
,
Laurus nobilis
,
Thuja orientalis
,
Citrus sin-
ensis
,
Citrus limon
, and
Origanum vulgare
were evaluated in a preliminary fumigation screening test
on 10-, 25- and 31-days-old larvae, 2-days-old pupae and 10- and 60-days-old adults of
Tribolium con-
fusum
. Beetles were exposed to essential oils’ vapors at a series of concentrations ranging from 0.27 to
165 μl/l of air depending on the essential oil, insect developmental stage, age and sex. All but
O. vul-
gare
essential oils exhibited strong fumigant toxicity to all developmental stages of
T. confusum
. In
general, 10 day-old larvae were the most susceptible and the 25 and 31 day-old larvae were the most
tolerant. LC
50
values ranging between 1.8 and 109 μl/l air depending on the essential oil and insect de-
velopmental stage, age and sex. Furthermore, pupae exposed to these essential oil vapours showed
various degrees of inhibition of morphogenesis.
Additional keywords
: Adultoids, developmental stage, inhibition of morphogenesis, mortality
,
larvae, pupae
mammalian toxicity (Hall and Oser, 1965; Is-
man, 2000) and degrade rapidly in the envi-
ronment (Rebenhorst, 1996; Misra and Pav-
lostathis, 1997).
Apart from their fumigant and acute tox-
icity against a wide spectrum of insect pests
(Huang
et al
., 1997; Shaaya
et al
., 1997; Pa-
pachristos
et al
., 2004; Rajendran and Sriran-
jini, 2008; Michaelakis
et al
. 2009; Wang
et
al
., 2009; Michaelakis
et al
., 2011), they can
also act as repellents (Jilani
et al
., 1988; Pa-
pachristos and Stamopoulos, 2002; Kumar
et
al
., 2011; Giatropoulos
et al
., 2012), antifeed-
ants or they can adversely affect the growth
rate, reproduction and behaviour of insect
pests (Stamopoulos, 1991; Liu and Ho, 1999;
Papachristos and Stamopoulos, 2002; Sta-
mopoulos
et al.
, 2007; Papachristos and Sta-
mopoulos, 2009; Ebadollahi, 2011).
Insects belonging to the family Tenebri-
onidae and especially to the genus
Tribolium
are considered major pests of stored prod-
ucts. Both
Tribolium confusum
Jacquelin du
Val and
Tribolium castaneum
(Herbst) at-
tack a wide range of starchy materials such
as flour, bran or cracked grain kernels, and
can occasionally be found in dried fruits,
spices and chocolate (Aitken, 1975; Mills and
Pedersen, 1990). Moreover, species belong-
Introduction
The measures used worldwide to con-
trol stored product insect infestations rely
mainly on the use of fumigants such as me-
thyl bromide and phosphine. However, their
usefulness is severely limited by their ad-
verse effects on the environment and non-
target organisms (Dansi
et al
., 1984; Fields
and White, 2002) and by the development of
resistance (Boyer
et al
., 2012). This situation
led researchers to develop safe, low-cost al-
ternatives that are convenient to use and
environmentally friendly. Among the most
promising of these agents are essential oils
directly toxic to bacteria, fungi and insects
(Isman, 2000; Isman and Machial, 2006).
Equally important, essential oils have low
