Aaliya Afroz, Ph.D. Scholar, Indira Gandhi Krishi Vishwavidayala, Raipur (C.G)

1. Role Of Diatomaceous Earth (DE) And Essential Oils in the
management Of Store Grain Insect Pests
Presented by
Aaliya Afroz
Ph.D. Scholar
Department of Entomology, IGKV, Raipur (C.G)
Seminar Incharge
Dr. S. S. Shaw
Professor

2. Stored grain Insect pests

3. Introduction
Insects are major pests of stored food causing losses estimated around 20%
of the annual world crop production (Sallam, 1999).
Residual insecticides are the most commonly used protectants in stored
grain against stored-product pests.
However, these protectants are toxic to mammals and leave residues in the
product.
DEs are very promising alternatives to traditional residual grain
protectants.
They are of natural origin, non-toxic to mammals and can be applied with
approximately the same technology as the residual pesticides.

4. What is Diatomaceous Earth?

5. Diatoms
Diatomaceous earth
Shells of Diatoms
Diatomaceous Earth
It is an inert dust derived from amorphous
sediment and comprised of the fossilised
carapaces of unicellular algae.
Physical properties:
light material
low density
colour ranges from white to dark grey.
Composition:
80-93% silicon dioxide
the remaining content comprising clay
minerals, organic matter, quartz, calcium,
magnesium carbonate.

6. History
"Bathing in sand” is a well known occurrence exhibited by birds and
poultry protecting themselves against mites and other parasites.
4000 years ago, observations of such natural phenomena probably led the
Chinese to use DE (diatomite) to control pests.
In 1880 in the United States, it was noticed that road dust killed
caterpillars of the cotton moth.
Until the 1950s, clay dusts, sand or silica gels were used more extensively
in practice.
In the early 1950s, DE was used to fight fruit moths, cucumber beetles,
Mexican bean beetle larvae, stored-products pests and cockroaches.

7. C. Sitophillus sp.
covered with DE
Abrasion of
the cuticle
Absorption of
cuticular waxes from
the epicuticle surface
Damage to
the digestive
tract
Blockage of the
spiracles and
tracheae
B. Dust form of DEA. Sitophillus sp. on wheat
The dust particles are trapped by the bodies of the insects as they
walk over it.
A B
Mode of Action
(Shah and Khan, 2014)

8. Scanning electron microscope photographs of Silica
particles exposed seeds and Callosobruchus maculatus
Treated
Control
d. Elytra
Abrasion
c. Seed coat of green
gram
b. Dorsal view
of insect
a. Ventral view
of insect
(Ganesh et al., 2015)

9. Relative
humidity
Temperature Type of
product
Growth stage
High RH or
moisture
content values,
desiccation on the
cuticle of insect is
reduced
There is a
positive
correlation
between
temperature
and mortality
The efficacy of
DE is
determined by
the type of
storage product
the dust is
applied to
Larval instars
differ in their
susceptibility
to DE
Factors Affecting Efficacy Of DE
(Shah and Khan, 2014)

10. Source of DE Method of application
Factors Affecting Efficacy Of DE
1. DEs from different
geological sources have
different-
SiO2 content
tapped density
oil absorbency
particle size
pH
2. These are correlated to
their insecticidal efficacy
against stored-product
insects.
Slurry treatments are
less effective than the
dry dusts.
DE Surface
(Shah and Khan, 2014)

11. Species variation
Contd.
Order of most susceptible to resistant species against DE
Cryptolestes < Sitophilus spp. < Oryzaephilus < Rhyzopertha < Tribolium spp.
(Korunic and Fields 1995; Fields and Muir 1996)
Factors Affecting Efficacy Of DE

12. Concerns About The Use Of Diatomaceous
Earths
1. Effects on grain quality
When DE is mixed with grain at the currently recommended
dosages of 500-3500 ppm
Physical and mechanical properties of the bulk commodity are
adversely affected
Flowability and bulk density of kernels are reduced.
Magnitude can be reduced by lowering concentrations of DE to 50-
100ppm
(Korunnic 1997; Korunic et al., 1998)

13. 2. Health issues
* No evidence of acute or chronic
toxic effects of natural DE.
* Rats receiving daily food containing
5% freshwater DE showed no signs of
abnormality after 90 days (Bertke 1964).
* If inhaled
Amorphous silica - minimal health hazard
crystalline silica - silicosis, emphysema and pneumoconiosis.
* The US Environmental Protection Agency (EPA) allows the use of DE in
product storage and the food processing industry.
DE

14. Resistance Development Against DE
For DEs, only a physical mode of action is involved, development of
physiological resistance to DEs is unlikely to occur (Golob, 1997)
However, newer studies indicate that resistance may be developed at least in
the case of some species.
A study by Athanassiou et al. (2005) using SilicoSec found that T. confusum
adults could survive at dose rates that caused 100% mortality to S. oryzae
adults.

15. Efficacy of enhanced diatomaceous earths
Many DE formulations are only effective at dose rates of 1000 ppm or
more.
Solutions to the problems :reduced-risk methods
- extreme temperatures
- entomo- pathogenic fungi
Combined use of-
Diatomaceous
Earth
Beauveria
bassiana
Sitophilus
granarius
(Adult)
Natural
pyrethrum
Tribolium
confusum
(Pupa)
Athanassiou and Steenberg (2007),
Vayias et al. (2006)

16. Role of Essential oils in management of
stored grain insect pests
Introduction
The ecotoxicological, environmental, and social consequences of chemical
insecticides in agriculture have led researchers to find viable alternatives
that are more environmentally friendly than synthetic chemicals.
In this context, the use of insecticides based on botanical extracts, essential
oils (EOs) are a promising alternative.
They are secondary metabolites synthesized by plants, and they play very
important roles in plant defense and signaling processes.

17. They are monoterpenes and sesquiterpenes synthesized in the
cytoplasm and plastids.
In many storage systems, fumigants are the most economical and
convenient tools for managing stored grain insect pests.
Methyl bromide and phosphine are being phased out.
Hence, there is a need to develop selective management
alternatives with fumigant action.
Essential oil from >75 plant species had been studied for their
fumigant toxicity against several insect pests of stored grain
(Rajendran and Sriranjini, 2008).
Contd.

18. Effects of EOs on insects
Contact and
ingestion toxicity
Repellant toxicityFumigant activity
Sublethal
physiological
effects
Cymbopogon martinii
EO
(LD50 - 22.8 μg/cm2)
P. interpunctella
(Emiliano et al., 2017)
Artemisia scoparia
EO
( LC50 - 2.05 μL/L)
T. castaneum
(Maryam et al., 2006)
Ocimum
gratissimum EO
( 0.2μL/g grain)
S. oryzae
(Ogendo et al., 2008)
Decrease in potential
fecundity
Egg viability
Decreased lifetime
fecundity

19. Contd.
Sublethal physiological effects
Decrease in potential
fecundity
Decreased lifetime
fecundity
Egg viability
T. castaneum and T. granarium
EO of aerial parts of
Cinnamomum camphora,
Ocimum basilicum,
Chenopodium ambrosioides
and seeds of Pimpinella
anisum (1.50 ml /cm2)
Allium sativum
EO
S. oryzae and T. castaneum
Fumigant toxicity
of Artemesia khorassanica EO
(LC50 : 9.60 μl/liter air)
Plodia interpunctella
(LC50 : 1.52μl/liter air)
(Neenah and Ibrahim, 2011) (Yang et al., 2010) (Borzoui et al., 2016))

20. produced larvae with
significantly reduced energy
content, by decreasing
protein, lipid, and glycogen
contents.
exposed to sublethal dosages of EOs
extracted from Artemisia khorassanica
and Vitex pseudo negundo
Plodia interpunctella
(Adult)
1. The intrinsic properties of EOs interfere with basic metabolic,
biochemical, and physiological functions of insect pests.
For example:
Mode of Action
(Ehsan et al., 2016)

21. Adults resulting from
larvae treated with
EOs presented fewer
regenerative cells in
the midguts
2. Ingestion of EOs - histological modifications in insect.
T.S. in the mid gut of larva
(a) control IV instar larva
(b) treated IV instar larva with 0.50 mL diluted
caraway oil
(c) treated IV instar larva with 2 mL diluted carvone
(Salah et al., 2016)
T. granarium
(Adult)
T.S. in mid gut of female adult of T. granarium
(a) Control
(b) treated as 4th instar larvae with 0.50 mL diluted
caraway oil
(c) treated as 4th instar larvae with 2 mL diluted
carvone.
T. granarium
(Grub)
-Severe histological changes
in their midguts concerning
mainly the regenerative cells
-Cells of hypodermis
necrotic and blackened, with
no differentiation between
exocuticle and endocuticle.

22. Essential oils effect at synaptic junction
Essential oil
compounds from essential oil
3. Neurotoxic actions of EOs
Among mechanisms of action, the inhibition of acetylcholinesterase (AChE) is
one of the most investigated in stored product pests.

23. S.No. Target pest Plant
Major chemical
constituent of
essential oils
Percentage Reference
1
Trogoderma
granarium
Cinnamomum
camphora Linalool 84.3 Gomah et al., 2011
Ocimum
basilicum
Methyl eugenol 71.3 Gomah et al., 2011
Chenopodium
ambrosioides
α-terpinene
49.8
Gomah et al., 2011
2
Tibolium
castaneum
Pimpinella
anisum
(E)-anethole 81.2 Ahmed et al., 2018
3 C. maculatus Pistacia khinjuk
Monoterpene
Sesquiterpene
56.8
41.1 Maryam et al., 2018
4
T. castaneum
Artemisia
absinthium
Camphor 24.81 Iqbal et al., 2017
5 S. zeamais Lippia sidoides Thymol 68.5 Alexander et al., 2017
Essential oils effective against some common
stored grain insect pest

24. Atalantia monophylla
Hydrodistillated essential
oil
• Fumigation toxicity (70.22 %)
• Repellent activity (85.24 %)
• Ovicidal activity (100 %)
against Callosobruchus maculatus
Essential oil against insect
Predominant compounds
• Eugenol (19.76 %)
• Sabinene (19.57 %)
• 1, 2- dimethoxy- 4 -
(2-methoxyethenyl)
benzene (9.84 %)
• Beta-asarone (7.02 %)
• Methyl eugenol (5.52 %)
(Nattudurai G et al., 2017)

25. Conclusion
Plant essential oils can be used in a variety of ways to control large number
of insect pest.
It may require frequent replication, as they are effective for particular time
duration considerably.
Due to their volatile nature they have lower level of risk to the environment
and mammals, hence compatible with integrated pest management
program.
The oils from plant species may have an interesting potential as natural
repellents and insecticides .
However, the evaluation of these activities under industrial conditions is
mandatory to prove their practicable application.

26. Contd.
DEs are the most efficient among all inert dusts for the management of
stored-product pests.
The major bottle- neck in their wider adoption is the decrease in grain bulk
density caused by addition of high doses of DE dusts.
However, inclusion of different classes of low toxicity insecticides with DE
formulations enables control at lower doses, although results vary with
target species.
Thus, the best combinations need to be worked out for each situation and
only then will enhanced DE formulations find a place in the market in
competition with currently used synthetic insecticides.