This document discusses fumigation techniques for pest management. It begins by outlining the importance of reducing food losses to pests in order to enhance global food security. It then describes how fumigation works, involving the introduction of pesticides in an enclosed space in gaseous form. Various fumigation methods are outlined for different situations, like direct mixing or surface application for stored grains. Specific fumigants are also described like methyl bromide, chloropicrin and aluminum phosphide. The document provides details on fumigation best practices, advantages and disadvantages.

1. Detail account of fumigation
techniques in pest management
BY:
JAYANT YADAV, CCSHAU, HISAR, HARYANA

2. Preface
 Current world population is expected to reach 10.5 billion by 2050
(UN March, 2013), further adding to global food security concerns
 Food and Agriculture Organization of U.N. predicts that about 1.3
billion tons of food are globally wasted or lost per year
(Gustavasson, et al. 2011).
 Reduction in these losses would increase the amount of food
available for human consumption and enhance global food security
 Unsatisfactory control of pests in stored products results in
contaminated products that can cause health, financial, legal and
aesthetic problems
 Fumigants provide effective & economical control where other
forms of pest control are not feasible.
 A variety of pests may be found in stored commodities and food
processing facilities, depending upon geographic location, physical
nature of the facility, and the type of food being processed.

3. Introduction
• Fumigation is the process of introducing a pesticide into an
enclosed space in such a manner that it disperses quickly and
act in a gaseous state on the target organism.
• A fumigant is a chemical vapor or gas that, when released,
penetrates objects or enclosed areas in concentrations that
are lethal to pest organism.
Toxicity of fumigants to insects
• fumigants enter the insect mainly by way of the respiratory system.
• To enter insect eggs, gases diffuse through the shell (chorion) of the
egg or through specialized "respiratory channels"
• poisoning of an insect by a fumigant is influenced by the rate of
respiration of that insect; any factor that increases the rate of
respiration tends to make the insect more susceptible

4. Impact of environment on fumigants
1. EFFECT OF TEMPERATURE
• most important environmental factor
• range of normal fumigating temperatures from 10 to 35°C
• the concentration of a fumigant required to kill a given stage of an
insect species decreases with the rise in temperature.
• At temperatures below 10°C, increased sorption of the gas by the
body and also the resistance of insects may be weakened by the
effects of exposure to low temperatures.
2. EFFECT OF HUMIDITY
• it is not possible to make any general statements about the
influence of humidity on the susceptibility of insects to fumigants
3. EFFECT OF CARBON DIOXIDE
• Carbon dioxide may stimulate the respiratory movements and
opening of spiracles in insects.
• With flammable fumigant like ethylene oxide and methyl formate
carbon dioxide may work to advantage both by reducing the fire or
explosion hazards and by increasing the susceptibility of the insects.

5. 4. PROTECTIVE NARCOSIS
• Some fumigants can produce paralysing effects on insects
• hydrogen cyanide (HCN) , if certain species are exposed to
sublethal concentrations before the full concentration is
applied, the resulting fumigation is less effective than one in
which the insects are subjected to the full concentration from
the very beginning
• Similar in case of phoshine in introduced at higher conc.

6. Dosages and concentrations
• The dosage is the amount of fumigant applied and is usually expressed as
weight of the chemical per volume of space treated and expressed as
g/m3 or g / quintal of grain
• While concentration is the actual amount of fumigant present in the air
space in any selected part of the fumigation system at any given time .
• CALCULATIONS FOR CONVERSION OF DOSAGE INTO CONCENTRATION
VALUES
Example. To convert 1g/m³ of PH3 (molecular weight 34 approximately)
• (1x22.4)/34 = .659 cm³per litre
= 659 parts per million by volume
CONCENTRATION X TIME (c x t) PRODUCTS
Most fumigation treatments are recommended as grammes per cubic metre
followed by a statement of the length of the treatment in hours.
For eg - to kill 99 percent of larvae of Tenebroides mauritanicus (L.) at 20°C, a
concentration of 33.2 milligrammes per litre of methyl bromide must be
maintained for 5 hours. The product 33.2 milligrammes per litre x 5 hours =
166
-milligrammes per litre x hours is known as the concentration x time
product needed to obtain 99 percent control of this insect and
expressed as mg h/ lt

7. ADVANTAGES OF FUMIGATION
• Fumigants are usually quick acting and can result in total
eradication of the pest.
• Fumigant kill all insects irrespective of the type of their mouth
parts or their mode of feeding
• Fumigant are toxic to all forms of life ,therefore it is possible
to control all life stages of the pest
• Reduced residue problems in treated areas
• Because fumigants are gases, they diffuse through all parts of
the structure or commodity being treated and can reach pests
control materials or techniques.
• For certain commodities, fumigation is the only practical way
to control pests.

8. DISADVANTAGES OF FUMIGATION
• The control achieved through fumigation is temporary i.e
there’s no residual action from fumigants. Where untreated
populations of the pests remain, re-infestation of the treated
site can take place quickly.
• Fumigants are toxic and often highly hazardous to the
applicator, requiring special precautions during application
• Some commodities or pieces of equipment may be damaged
by certain fumigants and must be removed or otherwise
protected.
• Fumigant activity may be greatly affected by temperature.

9. TYPES AND
NATURE OF
FUMIGANTS
1. Methyl Bromide
 Methyl bromide is a colorless, odorless
and tasteless gas and it is usually
formulated with a small amount if
chloropicrin as a warning agent.
 Against insects, methyl bromide appears
to exert its principal toxic effect on the
nervous system.
 Methyl bromide is also used as a soil
fumigant to control fungi, weeds,
nematodes and insects.
 Methyl bromide is sold as a liquid
pressure. Upon release, it vaporizes to
form a gas that is about 3.3 times
heavier than air.
 Methyl bromide reacts chemically with
sulfur products and should not be used
to fumigate materials such as avocado,
soybean flour, flours , baking powder
,rubber and woolen goods.

10. 2. Chloropicrin
 Chloropicrin fumigants include products marketed under the
names Chlor-O-Pic, Lavacide 100 and Quasar. These products
contain nearly 100-percent chloropicrin and are marketed as
liquids .
 Chloropicrin volatilizes to form a dense gas that is about 5.7
times heavier than air.
 Chloropicrin is highly toxic to insects, vertebrates, and many
soil microbes, such as fungi. It’s highly irritating to eyes and is
powerful “tear gas.”
 Uses of chloropicrin on foodstuff have been restricted in
recent years.

11. 3. Aluminum Phosphide
 Aluminum-phosphide fumigants include products marketed under the
trade names Detia, Fumitoxin, Gastoxin, Phostex and Phostoxin.
 These products contain aluminum phosphide in combination with inert
ingredients such as ammonium carbamate and urea. The formulated
material is a solid molded into pellets or tablets.
 The active ingtedient, aluminum phosphide, reacts with atmospheric
water to produce hydrogen-phosphide gas. This gas is known as
phosphine. Phosphine is a colorless gas with an odor that smells different
to different people.
 Phosphine has an inhibitory effect on insect respiration and is unique in
that it is only toxic to insects in the presence of oxygen - in the absence of
oxygen it is not absorbed and is not toxic to insects .
 Phosphine is only slightly heavier than air, about 1.2 times heavy and it is
reactive and very corrosive metals, especially copper, silver, gold, and
platinum.

12. 3. Magnesium Phosphide
 Magnesium phosphide is similar to aluminum phosphide,
releasing hydrogen phosphide gas in reaction with water.
Release of the gas is faster than occurs with aluminum
phosphide.
 Common magnesium phosphide products contain the solid
magnesium-phosphide material attached to a strip or blanket
that can be put in place very quickly.
 Magnesium-phosphide fumigants can be used effectively for
warehouse and processing plant fumigation.

13. Techniques of fumigation for stored grains
1. DIRECT MIXING (VERTICAL STORAGE)
 By this method, the fumigant is applied to the grain so that it
is distributed as evenly as possible from the beginning of the
treatment.
 Direct mixing is often employed when infestation is general
throughout the mass and when there is access to the grain
stream during filling or transfer from one bin to another
 Only solid or liquid-type fumigants are used in this way.
 Aluminium phosphide tablets or pellets can be inserted in the
grain stream by hand or with an automatic dispenser
calibrated to deliver a dosage appropriate to the rate of
loading in the bin and Calcium cyanide is usually discharged
from an automatic applicator.
 Storage bins of the vertical type usually have manhole covers
in the ceiling and these are usually closed immediately to
prevent loss of fumigant

14. 2. SURFACE APPLICATION (FLAT STORAGE)
 The surface application method has so far been used mainly with
liquid type fumigants.
 The liquids are sprayed evenly over the top surface of the grain and
the vapours slowly evolve and diffuse downward through the bulk
 Carbon tetrachloride has given good distribution in grain in deep
bins, carbon disulphide has been used in many countries, although
its tendency to burn or explode is well known, Propylene oxide has
been used in France and Algeria.
(a) Larqe Bulk Fumigation
 The liquid-type fumigants are usually applied to the surface of bulk
grain by means of sprayers and the nozzles are removed to facilitate
the rapid application of the liquid to the surface of the grain
 A method for treatment of high vertical bins of grain by applying
methyl bromide with carbon dioxide has been developed by
Calderon and Carmi (1973) . The carbon dioxide acts as a carrier and
will take the methyl bromide down through the grain mass to the
bottom of the bin.

15. • In flat storage units, in which the depth of the grain does not
exceed 10 m (about 30 ft), tablets, pellets or sachets
containing aluminium phosphide may be used.
• The fumigant is usually applied by probing into the grain

16. 3. SURFACE INFESTATION
 With certain species of insects, such as the Indian meal moth,
Plodia interpunctella infestation may be confined to the top
of the grain. This problem cannot be solved by the usual
method of surface application of fumigants because the
vapours diffuse down through the grain.
 In silo bins or other storage units, which can be made air tight
surface infestations can be treated with materials such as
dichlorvos to obtain control
 It should also be pointed out that incipient surface
infestations of insects may be arrested by using pyrethrum,
malathion or other approved materials applied as a fine mist
in the space over grain

17. 4. HOT SPOT FUMIGATION
 Treatment of localised areas in a grain mass is often a useful
technique for dealing with incipient infestation
 These spots are usually recognised and defined by local rise in
temperature
 Liquid type fumigants are applied through tubes .
 Aluminium phosphide tablets are the best materials in use
 Enough fumigant is applied to maintain the required lethal
concentration not only in the region of infestation ,but also in
the margins surrounding it for 1 or 2 m

18. 5.TENT FUMIGATION
 A tent ( polythene or nylon
impregnated with vinyl chloride ) is
constructed to cover sacks of grains
Tent can be conveniently stretched
The fumigant is introduced in to the
tent through hoses connected to the
preparing equipment
Most commonly HCN is used as
fumigants

19. 6. VACUUM FUMIGATION
 This is done in the case of cotton bales, imported products
likely to be infested by insects, packaged food .
 The article to be fumigated is placed in a tight sealing steel
chamber from which the air has been sucked out to produce a
partial vacuum
 A fumigant heated 120°F
 Due to the partial vacuum the fumigant is able to penetrate the
deeper layers of the bales .
 The reduction in the oxygen content due to partial vacuum
forces the insects to breathe in toxic gas more readily
 Today, the technique is used chiefly in plant quarantine work
and for fumigating tobacco and other materials, such as
compressed bales of jute bags and pressed dates which are
difficult to penetrate at atmospheric pressure.
 Fumigants -Ethylene oxide/carbon dioxide mixture , Methyl
bromide , Hydrogen cyanide

20. Vacuum fumigator

21. Fumigation for rodents control

22.  Most commonly employed chemical control measures inclide
poison baits and fumigation.
 Initially poison baits are employed for control like Zinc
phosphide(2%), Racumin bait, norbormide etc.
 But to control the residual population of rodents fumigation is
necessary to kill more than 90% of population, otherwise they
breed so fast that population reaches the same level within
months. For this
 Fumigation with Aluminium phosphide tablets, 2 tablets of 0.6
g or half of 3g per burrow have been found effective.
 After introducing a tablet into live burrow, the opening is
closed tight with soil.
 Soil moisture is essential to produce deadly phosphine gas.