Storage pests and their control manual

Contents - Previous - Next

by JOSEFINA M HILARIO

This paper is a summary of pest control procedures currently being followed by the National Food Authority of the Philippines in accordance with internationally-accepted practices. No attempt is made here to present a detailed discussion of the basic concepts and principles of pest control as the author presumes that the participants has already obtained these information elsewhere. The exercises described here are intended merely to complement previous lectures on the subject and thus familiarize the participants with the manner in which the different pest control techniques are carried out in practice.

EXERCISE I FUMIGATION

A. Materials and Equipment:

1. Phosphine fumigation

Fumigating sheets
Sand bags
Phostrays
Phostoxin tablets
Warning signs
Masking tape
Protective clothing
Gas maske
Hand gloves
Phosphine gas detector

2. Methyl bromide fumigation

Fumigating sheets
Sand bags
Jiffy applicators
Evaporating pan
Methvl bromide, 1.5 lb. tin cans
Halide detectors
Alcohol
Match
Warning signs
Masking tape
Protective clothing
Gas mask
Gas extraction machine

B. Computations:

For phosphine fumigation:

Number of tablets = total volume or weight of pile x dosage

For methyl bromide fumigation:

Number of tin cans @ 1.5 Ib. = Total volume of weight of pile.

C. Procedure:

Fumigation is the application of a chemical which, at a required temperature and pressure, can exist as a gas in sufficient concentration to be lethal to a given pest organism. This treatment is resorted to as a remedial measure to control internal infestation. Fumigants, in contrast to other pesticides, are capable of diffusing and penetrating tightly-packed materials and can reach pests even inside grain kernels. They are effective against insects in all stages of development egg, larvae, pupa and adult.

Fumigation may be carried out under gasproof sheets or in lightly sealed enclosures. Fumigation under sheets:

The goods most often fumigated under sheets are cereals and other plant products in bags and the principal fumigants used are methyl bromide and phosphine. Gasproof sheets which retain fumigant vapors for a sufficient time when placed over infested materials may provide a safe and effective method of fumigation. This technique makes it possible to treat infested materials in situation, e.g. without moving them from their usual trade channels.

1) Preparation of stock: a. Prepare the stock by sealing all openings that would lead to the downward leakage of the fumigant during treatment. Inspect the fumigating sheets and repair rips and holes with masking tape to prevent leakage of gas. b. Hoist the sheets to the top of the stack leaving the ends hanging at the side with three feet extra sheeting for sealing edges to the floor. If sheets are not large enough, two or more may be joined by rolling together about three feet of the edges of each of the adjoining sheets.

2) Application of Fumigants:

a. If methyl bromide is to be used-in small piles, form a"dome" by propping bags against each other. In large stacks, a long space two bags deep and two bags wide should be made by lifting adjoining bags to form a trench. Lay a pan or can to receive the liquid discharging from the end of the outlet tube. Spread the sheets to completely cover the entire stack leaving the punching mechanism of the jiffy applicators outside the sheets on the floor. Seal the edges of the sheets to the floor by using sand bags. Apply the fumigant using the necessary protective devices.

b) If aluminum phosphide is to be used - the tablets, pellets, or sachets may be applied by evenly distributing them into phostrays and placing in strategic locations around the base of the stack. Sachets may be bound in lots of ten and dropped over or in the sides of the stacks in evenly-spaced positions prior to sheeting. Rubber gloves should be warm when directly handling tablets, pellets or sachets. Spread the sheets to completely cover the entire stack. Seal the edges of the sheets to the floor by using sand bags.

3) Leakage

a) When using methyl bromide, a careful check should be made with the leak detector around the base of the stack immediately.

b) Bolled junctions should also be tested.

4) Aeration

a) Operators must wear gas masks during the process of airing until dangerous concentrations of the fumigant have diffused.

b) Open all doors and windows and run exhaust fans.

c) Aeration should begun by, quickly lifting several sheets of each corner of the stack, in cases where gas extraction machine is not available, more sheets maybe lifted after a time interval.

EXERCISE II - PROTECTIVE SPRAYING

A. Materials: Equipment:
Pail Water
Stirrer Regular grade gasoline
Graduated Cylinder Protective clothing
Motorized knapsack' sprayer Respirator

Emulsifiable concentrate Hand gloves insecticide

B. Computations: Volume of solution = Total surface area x rate of application

C. Procedure:

Protective or surface spraying is applied on the external surfaces of stacked commodities to prevent insect attack and control existing infestation, if any. This consists of a spray application on the four sides and the top surface of the bag stack. Protective spraying must be done after receipt of stack and after fumigation on a regular basis. Before spraying, thorough cleaning of the stack be carried out to achieve effective control.

Fill the pail with the required volume of water and add the necessary amount of insecticide measured by a graduated cylinder. Stir the solution thoroughly and pour into the solution tank of the sprayer. Supply on the exposed surfaces of the stack and the surrounding areas taking care not to drench the bags. Refill as may be necessary. Use protective devices in preparing and applying the spray.

EXERCISE III - RESIDUAL SPRAYING

A. Materials and Equipment:

Drum Water
Pail Gasoline
Stirrer Protective clothing
Compressurized power sprayer Respirator
Weetable powder insecticide Hand gloves

B. Computations:

Volume of solution = Total surface area x rate of application

C. Procedure:

Residual or fabric spraying is applied in the structure of an empty warehouse or portion of a warehouse about to receive commodities for storage. Before spraying, thorough cleaning of the warehouse should be carried out. Residues from previous warehouse operations should be removed, burned or properly treated since they serve as a good source of reinfestation.

Weigh the required amount of insecticide, place it in a pail and add just enough water to produce a cream. Pour the creamy solution to the drum and fill up with water to produce the required volume of solution. Stir to ensure complete dispersion of the powder. Spray the deluted solution on ail internal surfaces including floors, post, trusses and ceiling. Use protective devices in preparing and applying the spray.

EXERCISE IV-FOGGING

Thermal fogger Diesel oil
Pail Gasoline
Stirrer Protective clothing
Graduated cylinder Respirator
Stainer Hand gloves

B. Computations:

Volume of solution = Total volume of wareouse rate of application

Volume of diesel oil = Capacity of solution tank - volume of insecticide

C. Procedure:

Fogging is the application of smoke or fog containing insecticide in an enclosed warehouse. This is done to control infestations of flying or migratory insects or those not controlled by residual treatment. Fogging should be applied at a time of day when insects are most active, generally at dusk. In order to achieve effective control, the treatment should be repeated at frequent intervals. When fogging, make sure that all openings of the warehouse are properly sealed.

Fill the pail, with the required volume of diesel and add the necessary amount of insecticide measured by a graduated cylinder. Stir the solution thoroughly and pour into the solution tank of the fogger using a strainer. Dispense the fog making sure that it is evenly distributed throughout the warehouse. Refill as be necessary. Use protective devices when preparing and applying the fogging solution.

EXERCISE V - RODENT BAITING

A. Materials and Equipment:

Sample pan Rodenticides
Bait stations Hand gloves
Bait material Beam balance

B. Computations:

Number of baiting stations = Length (m) + I x Width (m) + I

Weight of bait - Number of baiting stations x 100 gm.

Weight of rodenticide = Weight of baidt x 1/36

Weight of bait material= Weight of bait-weight of rodenticide

C. Procedure:

Rodent baiting makes use of single dose (acute) poisons and multiple-dose (chronic) poisons mixed with a suitable material or as ready-bait preparation. The use of acute poisons is being restricted because of the hazards of secondary poisoning and the development of bait-shyness among rodents. In the case of chronic poisons, rodents die after a few days of feeding and less possibility of developing bait shyness. Success of poisoning depends largely upon the choice and skillful placing of bait. Baits should be more attractive to rodents than their usual diet and should be stationed in strategic places. Baiting stations may be made of discarded oil cans or fabricated from wood materials.

Initially, only a few bait stations may be used to determine the rate of bait consumption. If baits are found to be consumed regularly and in large amounts, the number of bait stations may be gradually increased until the point of saturation is reached. Pre-baiting for two or three days is usually necessary when using chronic poisons. In pre-baiting, only the bait material is being offered minus the rodenticide. Sustained poisoned baiting then follows for a period of seven to ten days. Each bait station should contain about 100 gms of bait consisting of one part rodenticide for every thirth-five parts of bait material (for Tomorin or Ratoxin brands). Mix the bait thoroughly, considering contaminations with the skin. Place the bait in the stations and replenish as often as maybe necessary. Dispose the dead rats recovered by dumping or burning.

NATIONAL FOOD AUTHORITY

Quezon City

Recommended Pesticides/Fumigants and Their Application

  : RECOMMENDED
:PESTICIDE/FUMIGANTS
:FREQUENCY OF :APPLICATION :DOSAGE
:%
:RATE OF
:APPLICATION
1. Protective Spraying        
Equipment Used:        
a. Motorized Malathion 57 EC Every 2 weeks 1 1 li/40m
Knapsack Actellic 25 EC -do- 0.5 -do
(Stihl SG-17) Coopex 25 WP Every 3 weeks 0.1 1 li/30
2. Residual Spraying        
Equipment Used:        
a. Compressurized Gardona 75 WP Every 3 months 1 li/30m
Power Sprayer   Every 3 months 2 4 li/20m
(marunaka)        
b. Motorized        
Knapsack Coopex 25 WP Every 3 months 0.2 1 li/30m
(stihl SG-17)        
3. Thermal Fogging        
Equipment Used:        
a. Fogging Machine Malathion 95% As necessary 2 400 ml/500m
(Swing fog, Nuvan 93% Tech. As necessary 2 400 ml/500m
Dynafog) DDVP 93% As necessary 2 400 ml/500m
4. Ultra low-volume        
Nomthermal Aerosol        
Equipment Used:        
a. ULV Aerosol Bioresmethrin As necessary 0.2 150 ml/500m
Generator 0.2%        
(microgen, Leco        
Mini)        
Fumigation Phostoxin (Exposure As necessary   Bagged grains:
  as necessary tine is     15-45 tablets
  3 to 5 days)     per 1,000 cu. fit.
        Bulk storage:
        2-5 tablets
        per metric ton
        Space treatment:
        15-20 tablets
        per 1,000 cu. ft.
  Dowfume MC-2 or Methyl As necessary   Bagged grains:
  Bromide (exposure time     1-4.5 Ibs. per
  is 2 to 3 day.)     1,000 cu. ft.
         
  Detia Gas Ex-B As necessary   Bagged grains:
        3-5 bags per
        1,000 cu. ft.
        Bulk storage:
        1 bag per 1 to
        3 metric tons
        Space treatment:
        2-3 bags per
        1,000 cu. ft.
6 Rodent Sustained        
Baiting        
(Use of chronic Ratoxin   Monthly 0.029(1:35)  
poisons or anti-Tomorin   Monthly 0.029(1:35)  
coagulant) Ratak (ready mix)   0.005  

 

Types of Canisters Used with Respirators Recommended
For Respiratory Protection Against Certain Fumigants*

FUMIGANT DESIGNATION OF
CANISTER TYPE
USUAL CONTENTS
OF CANISTERS
Acrylonitrile, carbon disulfide    
carbon tetrachloride, ethylene    
chlorobromide, ethylene dibromide,    
ethylene dichloride, methyl Organic vapors Activated charcoal
bromide, naphthalene, trichloroethylene.    
(Also any mixture of these with a    
total concentration not exceeding 2%    
by volume in air)    
Chloropicrin, ethylene oxide, phosphine Organic vapors, Activated charcoal
(maximum PH3 concentration 0.5 % acid gases and soda lime or other
    alkaline granules
Hydrogen cyanide (HCN)**, Acid gases (a special Soda lime caustic
Sulfur dioxide canister is usually pumice or a sodium
  marketed for NCH) hydroxide preparation and
    activated charcoal
HCN**, chloropicrin Organic vapors, Activated charcoal
  acid gases (a special and soda lime or other
  canister is usually marketed alkaline granules.
  for HCN and chloropicrin**  

* Canisters will not give protection when the total concentration exceeds 2 per cent by volume in air.
** Certain fumigants, such as HCN, may be absorbed in toxic amounts through the skin
*** Chloropicrin is sometimes added in small proportions to HCN and methyl bromide to serve as warning agent.

SOMD/RRG/JMH/naa

TYPES OF FUMIGATION ENCLOSURE AND FUMIGATION PROCESS USED.

Type of enclosure Situation to betreated Fumigant and application process appropriate
Sealed permanent Fumigation chambers Methyl bromide (direct application), Phosphine (as a phosphide), hydrogen cyanide (direct application)
  Large silo bins (greater than 300 tonne capacity) Methyl bromide (recirculation), phosphine (as phosphide into grain stream, onto surface for squat bins), hydrogen cyanide (as Ca(CN)2 into grain stream).
  Small silo bins (less than 300 tonne capacity) Phosphine (as phosphide into grain stream, by probe or direct onto surface), methyl bromide (direct application), carbon disulphide (direct application).
  Storage sheds with bulk grain Phosphine (surface application or by probe), methyl bromide (recirculation).
  Storage sheds empty or with grain. Phosphine (as phosphide, distributed around store), methyl bromide (distributed by fan), hydrogen cyanide (distributed by fan).
Sealed movable enclosuresa Road and rail vehicles, freight containers Methyl bromide (direct application), phosphine (as phosphide, on surface of stow).
Barges and ships Methyl bromide (gravity penetration or by recirculation), phosphine (as phosphide, on surface of stow)
Temporary
enclosures
Under gasproof sheets Methyl bromide (direct application, sometimes with fan distribution), phosphine (as phosphide), carbon disulphide and chloropicrin (direct application, small quantities of grain only)
Spot fumigation Chloropicrin (inserted by probe), phosphine (as phosphide, by probe)

a Fumigation in transit is subject to strict control and may not be permitted with some fumigants and situations.

Rearing Temperatures, Media and Approximate Times of Development for the Test Species

Insect Rearing
temperature
Rearing medium

Rearing times

      First
emergence
(days)
Peak
emergence
(days)
Progeny
removed
(days)
Sitophilus oryzae 25C Wheat 35 36-43 63  
S. zeamais
Temporary
enclosures
Under gasproof sheets Methyl bromide (direct application, sometimes with fan distribution), phosphine (as phosphide), carbon disulphide and chloropicrin (direct application, small quantities of grain only)
Spot fumigation Chloropicrin (inserted by probe), phosphine (as phosphide, by probe)

a Fumigation in transit is subject to strict control and may not be permitted with some fumigants and situations.

Rearing Temperatures, Media and Approximate Times of Development for the Test Species

Insect Rearing
temperature
Rearing medium

Rearing times

      First
emergence
(days)
Peak
emergence
(days)
Progeny
removed
(days)
Sitophilus oryzae 25C Wheat 35 36-43 63  
S. zeamais 25C Wheat 35 36-43 63  
S. granarius 25C Wheat 34 36-43 63  
Rhyzopertha 30C Wheat + broken wheat      
dominica   (3: 1) 35 36-43 63  
Tribolium 30C Whole wheat flour + yeast      
castaneum   (12 1) 23 26-30 42  
T. confusum 30C Whole wheat flour + yeast