STORED GRAIN PEST MANAGEMENT

ENTOMOLOGICAL RESEARCH INSTITUTE, AARI, FAISALABAD

• Post Harvest Losses

• Insect pests of stored Grains

• Non Insect Pests of Stored Grains

• Role of Abiotic Factors

• Management of Stored Grain Pests

• Food Safety

• Quality assurance

• Better storage

• Better protection from pests

• Reduce losses (quantity & quality)

• Better marketing opportunities

Why is Post-Harvest Management

Important?

“Post-harvest losses are directly proportional to the backwardness of a nation”

Grain Flow Patterns Stored Grain Food Web

Types of Losses due to Pests

• Direct

• Indirect

Direct Losses

–Actual consumption

• loss of weight,

• loss of nutrients,

• lower germination,

• reduced grade

• lower market value

–Contamination

–Damage to structures or containers

Indirect Losses

• Grain heating

• Bacteria

• Fungi

• Alflatoxins

• Control and application costs

• Pesticide residues

• Loss of consumer confidence

• A. Abiotic – Grain Moisture

– Relative Humidity

– Temperature

• B. Biotic – Insects

– Fungi

– Bacteria

– Mites

– Rodents

– Birds

All provide conducive environment

to insect pests

All affect quality, seed viability as

well as quantity of grains

Factors Influencing Grain Loss During

Storage

• Post Harvest Losses

• Insect pests of stored Grains

• Non Insect Pests of Stored Grains

• Role of Abiotic Factors

• Management of Stored Grain Pests

X

Stored Product Pests

• 80% of human food comes from grains.

• 12% of harvest is lost to insects before harvest.

• Another 36% is lost after harvest due to insects.

• Overall total food losses due to pests are about 50% destruction.

Ideal Conditions for Pests

Environment Conditions

Temperature 20 - 40oC

Relative humidity 60-70%

Mixing grain lots

old and new

Two Pest Categories

• Primary – Cause initial injury.

• Secondary – Take advantage of injury.

Major Insect Pests of Stored Grains

a) Khapra Beetle (Trogoderma granarium)

b) Lesser Grain Borer (Rhyzopertha dominica)

c) Red Flour Beetle (Tribolium castaneum)

d) Saw Toothed Grain Beetle (Oryzophilus surinamensis)

e) Maize Weevil (Sitophilus zeamais)

f) Grain Weevil (Sitophilus granarius)

g) Rice Weevil (Sitophilus oryzae)

h) Flat Grain Beetle (Cryptolestes Furrigenius)

i) Pulse beetles (Callosobruchus chinesis, C. maculatus)

Major Insect Pests of Stored Grains

j) Angoumois Grain Moth (Sitotroga cerealella)

k) Rice Moth (Corcyra cephalonica)

l) Indian Meal Moth (Plodia interpunctella) m) Psocids ( Lepinotus spp. and Liposcelis spp)

Lifecycle Beetles 15-18 days

Moths 28 - 35 days

Pulse Beetle (Callosobruchus chinesis, C.

maculatus)

Host range:

All whole pulses, beans and grams.

Gram and Bruchids Callosobruchus chininsis

Callosobruchus maculatus

Adult morphs Dispersal (flying) form

is induced by high larval density to move to new,

higher quality habitats.

Long adult life span

Sexes are subtle

(Utida 1956, 1972).

Sedentary (flightless) form develops at low larval density

shorter adult life span

sexes are dimorphic

Gram Dhora or Seed beetle

Gram mung mash peas

cow peas arhar

Lentil

cotton seed maize sorghum

Host Range

Dorsal view of male and female of Callosobruchus chinensis

Callosobruchus chinensis

(Coleoptera: Bruchidae)

Dorsal view of male and female Callosobruchus maculatus.

Callosobruchus maculatus (Coleoptera: Bruchidae)

Adult

Adult beetle is 3 - 4 mm long,

oval shaped body is pointed

towards front.

The adult emerges out of the

pupa and lives for 5-20 days.

The size of the adult beetle

depends upon the size of the

infested portion of the pulse.

Bionomics

Eggs laid singly, stick into seed, fresh

eggs are translucent, white in color.

Egg period is 6 -16 days

Larva fleshy, curved, creamy in

color, black mouth part.

larval period 10 -38 days

Pupa pupation takes place in a seed

cell prepared beneath the seed coat. The pupal stage lasts 4-28 days

Cont…

Pulse Beetle Life Cycle

LIFE CYCLE

Source: Cork et al., 2009

The adult and grub feed on the grain by

making a small hole and cause 10-15%

loss.

Infested stored seed can be recognized

by the white eggs on the seed surface

and the round exit holes with the 'flap'

of seed coat.

Grains lose their germinating capacity

upto 50-92%.

Source:Adugna, 2006

Damage

• Post Harvest Losses

• Insect pests of stored Grains

• Non Insect Pests of Stored Grains

• Role of Abiotic Factors

• Management of Stored Grain Pests

X

X

Non Insect Pests

• Rodents

•Mites

•Microorganisms

• Birds

What is a Rodent ?

Rodents Damage

• Feed on grain

Rats 25 gm of food per day,

Mice 3-4 gm per day

• Spoilage and contamination of grain

• Damage materials –tarpaulins, bags, electric cables

Rodents Associated with Stored Grains

Three Species

• Black rat or Roof Rat (Rattus rattus)

• Norway rat or Common rat (Rattus norvegicus)

• House mouse (Mus musculus)

One Mouse, One Year…..

Mite Pests

• Mostly occur in damp or moist grain.

• Mites are not insects.

• Chiloglyphus and Acarus species are

considered most important mites of

stored cereals.

• Mites multiply under high humidity

conditions (over 65% relative humidity).

Mite Damage

• Direct damage by eating the germ of

the grain.

• Infested commodity becomes

tainted with off-flavours

• Affect the Seed Viability.

• Straw-itch mite´ can cause severe

dermatitis and allergic conditions in

people handling infested

commodities.

Fungi Associated with Stored Grains

Most common

• Aspergillus, Penicillium and Rhizopus

• Grain spoilage and mycotoxins (poisonous)

Development of Fungi is influenced by

• Moisture content of the stored grain

• Temperature

• Condition of the grain going into storage

• Length of time the is grain stored and

• Amount of insect and mite activity in the grain.

Fungi……

• Develop on the surface of & inside stored commodities that

have not been dried properly or which have become wet

during storage – emit mycotoxins which are hazardous to

human & livestock health (especially Aflatoxins).

• Aflatoxins are highly dangerous toxic residues produced by

certain fungi, such as Aspergillus flavus and A. parasiticus -

especially affect oilseeds, edible nuts and cereals.

• Cause aflatoxic hepatitis and enteroergotism.

• Toxins particularly carcinogenic in humans.

• Acts as an immuno-suppressant.

– Temperature (40 - 90o F ; 4 - 32o C)

– Relative Humidity (> 70%)

– Moisture (22-23% in grain)

– Oxygen (1-2%)

Storage Conditions that Favor Production of

Mycotoxins

Effects of Fungi on Food Grains

• Reduction of viability.

• Discolouration of embryos.

• Increase of free fatty acids.

• Production of toxins.

• Heating moulding and rotting.

• Mustiness of bad odour.

Bacteria Associated with Stored Grains

• Bacillus mycoides.

• Bacterium Coli.

• Bacterium herbicola.

• Clostridium butericum.

• Post Harvest Losses

• Insect pests of stored Grains

• Non Insect Pests of Stored Grains

• Role of Abiotic Factors

• Management of Stored Grain Pests

X

X

X

Effect of Moisture Content in Food Grains

• The storage life of the grain is closely

related to its moisture content.

• For safe storage, the moisture content in

the food grains should be less than 10

per cent.

• The moisture content in a mature grain

is about 16 to 18 per cent.

Effect of Moisture Content…

Seeds contain moisture above 14% -

• It increases the rate of physical and chemical changes

brought about by the action of microorganisms and enzymes.

• It increases the population and activity of insects, bacteria

and other microorganisms.

• The respiration of a large population of insects releases large

amount of heat, which may raise the temperature of the

stored food grain. This is known as DRY HEATING of

foodgrains.

• High moisture content in the food grains increases their size.

As a result, more space is required for their storage.

Effect of Moisture Content…

Below 5% seed moisture,

• Breakdown of membrane structure.

• Hastens seed deterioration.

• For every decrease of 1 per cent seed moisture content, the

life of the seed is doubled.

• (Applies only when the moisture content is between 5 to

14%)

Storage Moisture Content

• > 10 % insects can feed and reproduce

• > 12-14 % fungi can grow

• > 18-20 % heating due to seed respiration occurs

• 20-40 % germination occurs

Fluctuation in 0.5 % to 1.0 % moisture significantly

affect the rate and extent of insect infestation.

Effect of Moisture Content of Air (Humidity)

• High moisture content of air as well as high temperature

accelerates the growth of moulds in the stored food grains.

• Increase in temperature up to 66`C.

• Increase in moisture content from 14 to 18 per cent.

Wet Heating of Grains or Damp Grain Heating.

• Lowers the quality of stored food grains

• Affects the future germination of seeds.

Effect of Temperature

• It affects the growth of insects and microorganisms. which attack

the stored food materials.

Insects (maximum growth rate) 30` C and 32`C

Micro-organisms and enzymes (most Active) 30`C and 40`C.

• Damage to the stored food materials can be significantly reduced

by storing them at lower temperatures.

• A 10 °F decrease in temperature nearly doubles storage potential

of seed.

• The sum of the temperature in °F and the percent relative

humidity should not exceed 100.

• Post Harvest Losses

• Insect pests of stored Grains

• Non Insect Pests of Stored Grains

• Role of Abiotic Factors

• Management of Stored Grain Pests

X

X

X

AGENDA

X

Principles of Safe Storage

Three Principle,

• As dry as possible

• As cool as possible

• Regular inspection

Good Storage Practices – All Food Grains

Before Storage

• Check for leakage in rain water or sufficiency

of drainage facilities.

• Cleanliness of the facility and environment

around processing plant.

• Pesticide treatment.

• Security and fire fighting arrangements.

• Repairs of equipment's.

Good Storage Practices…

After receipt of seed/grain

• Inspect for variety, soundness and quality.

• Inspect for infestation – type and extent.

• Check whether seed/grain has excess moisture,

whether it had been heated up in earlier

storage and has any musty or rancid odour.

• Any grain rendered wet/damaged.

Good Storage Practices…

During storage

• Maintaining cleanliness inside the

processing plant/warehouse.

• Ensuring aeration wherever necessary.

• Monitor increase in seed moisture/insect

infestation through regular checking and

taking necessary control measures.

Management of Pests of Stored Grains

1. Sanitation of stores

2. Chemical control

3. Biological control

4. Controlled Atmosphere (Hermetic Storage)

5. Resistant varieties

6. Use of heat and cold environments

Rat Management

• Keep the store clean-remove any spilt grain

• Store bags in tidy stacks set up on pallets,

• Store any empty or old bags and fumigation sheets on

pallets, and if possible in separate stores!

• Keep the store free of rubbish Bum or bury it!

• Keep the area surrounding the store free of tall weeds

• Keep the area in the vicinity of the store free of any

stagnant water

Fungi Management

• Moisture content (12-14%)

• Heat

– dry heat at 65oC for 6 days

– hot water treatment at 52-55oC

• Fungicides

– Dithane M-45 and Benlate at 3 grams kg-1.

Thank You