Describes about the major pests of cereals

1. Pests of Cereals and Grains

2. Rhyzopertha dominica
(lesser grain borer)
• 200 and 500 eggs laid
• ovoid in shape
• laid outside grains either singly or
in clusters
•white when first laid, turning rose
to brown before hatching
• White to cream in colour
• Three pairs of legs and biting mouthparts
• undergo four instars
• quite mobile and linear in shape at first
• become more immobile and C-shaped as
they develop
Pupation takes place
inside the hollow shell of
the seed or in the "flour"
that accumulates with
infested grain.
• Adults can live up to 240 days
• brown to black beetles with
cylindrical bodies
• Development from egg to adult
depends on temperature (30 days in
summer )

3. Damage
• Both adult and larva damage the grain
by boring/eating.
• Post harvest storage of seeds and grains
are affected.
• The pest hollows previously undamaged
grains, eating the starch.
• The holes are characteristic with an
even edge.
• Adults and larvae feed on the entire
grain apart from the bran leaving
behind empty husks and flour.

4. Pest Management
• Detection methods
Damaged grain is distinctive (as detailed above). Infested grain may give off a sweet smell. Sieving a sample
of grain is the simplest detection method but it will only detect adults and larvae that are outside the grain.
• Cultural control
Removing spilt grain from around storage facilities can reduce lesser grain borer populations. So far the use
of resistant varieties has not been utilised as a control method.
• Physical control
The removal of adult insects from the grain by sieving can reduce populations but this is very labour-
intensive. The addition of inert dusts such as ash and clay to the grain can reduce insect numbers by causing
the insects to die from desiccation.
• Biological control
There are a few parasites and predators that attack the lesser grain borer but their effectiveness in the field is
uncertain. The fungus Beauveria bassiana can be used as a biological insecticide.
• Controlled atmosphere
Where suitable infrastructure exists, low oxygen and carbon dioxide-enriched atmospheres can be used to
control stored product pests.
• Freezing and Heating
Where the infrastructure exists, freezing for several days and heating for 24 hours have proved to be effective
control methods for stored product pests.
• Chemical control
The insecticides Chlorpyrifos-methyl and pirimiphos-methyl, while effective against most stored grain insect
pests, are not very effective against the lesser grain borer. The fumigant phosphine can be used in sealed
storage facilities. Pesticides are poisons so it is essential to follow all safety precautions on labels.

5. Sitophilus granarius
(wheat weevil)
• Females usually lay around 150
eggs, and up to 300 eggs
• Eggs are laid individually in cavities
that the female drills in the grain
kernels
• Cavities are sealed by a waxy plug,
• Eggs incubate for about 4-14 days
• One larva develops in each infested kernel
• Feeding larvae excavate a tunnel and may
keep feeding until only the hull remains
• There are four larval instars all of which
occur in the grain
Pupation also occurs
inside the grain
• Newly emerged adult chews its way
out of the grain
• Under warm conditions life cycle can
be completed within 4-6 weeks, but
can be up to 21 weeks
• Adults can survive for a month or
more without food in cooler
conditions. This species is flightless
but can walk fairly long distances

6. Damage
• Sitophilus granarius never attack the grains in
the field, in this way it is truly a stored grain
pest.
• Grains are damaged mostly by the adult
females while chewing it for making cavities in
the kernels of grain and by developing larvae
which feeds upon the interior contents of the
grain making them inconsumable.
• Adults and larvae feed upon wheat, com,
macaroni, oats, barley, sorghum and other
grains and grains products.

7. Pest Management
• Detection methods
Because the granary weevil larvae develop inside the grain it is difficult to detect the pest by visual inspection unless
its numbers are very high.
• Cultural practices
The severity of a granary weevil infestation can be reduced by good store hygiene: cleaning the store between
harvests, removing and burning infested residues, fumigating the store to eliminate residual infestations and the
selection of only uninfested material for storage. Harvesting the crop as soon as possible after it has reached
maturity will reduce the chances of attack by granary weevil and other storage pests. The use of resistant cultivars
may also reduce the severity of an infestation.
• Physical control
The removal of adult insects from the grain by sieving can reduce populations but this is very labour-intensive. The
addition of inert dusts such as ash and clay to the grain can reduce insect numbers by causing the insects to die from
desiccation.
• Biological pest control
Biological control with parasites, parasitoids and predators has not been practiced against the granary
weevil. Beauveria bassiana can be used as a biological insecticide to control granary weevil in stored maize. Bacillus
thuringiensis can be used on adults
• Controlled atmosphere
Where suitable infrastructure exists, low oxygen and carbon dioxide-enriched atmospheres can be used to control
stored product pests.
• Freezing and Heating
Where the infrastructure exists, freezing for several days and heating for 24 hours have proved to be effective control
methods for stored product pests.
• Chemical control
The granary weevil is susceptible to organophosphorus compounds such as fenitrothion and pirimiphos-methyl but
is not very susceptible to synthetic pyrethroids. Grain stocks can be fumigated with phosphine or methyl
bromide. Pesticides are poisons so it is essential to follow all safety precautions on labels.

8. Tribolium castaneum
(Rust-Red Flour Beetle )
• A female beetle lay about 400-500
eggs
• Eggs are laid singly in flour and
dust of the grains
• The eggs are minute, slender, and
cylindrical in shape, rounded at
both ends and of whitish colour.
•The incubation period varies from 5
to 12 days, depending on
temperature
• The freshly hatched grub is small, worm
like, slender, cylindrical ,wiry in
appearance and pale yellowish in colour
• The body segments have a number of fine
hairs
• The larval period varies from 27 to 29 days
• Pupation takes place
generally on the surface
of the food.
• The pupa is naked.
• At first it is white but
gradually becomes
yellowish.
• Pupal stage lasts for 5-9
days
• The body of the adult beetle is
flattened reddish-brown in
colour.
• The head, thorax and abdomen
are distinct.
• The total life cycle from egg to
the emergence of adult takes
about six weeks

9. Damage
• This pest is found infesting all stored
products like seeds, grains, flour, dry
fruits, nuts, oil cakes etc.
• Neither the larva nor the adult can
generally damage sound grains, but they
feed on those grains only which have
already been damaged by other insect
pests.
• This is a serious pest of prepared cereal
products such as atta, maida and suji and
is found in abundance in flour mills.

10. Management
• The first step in managing an infestation is to find and remove the source of the
infestation .
• cleaning is a crucial part of controlling these pests.
• Be sure to locate all infested material and discard it by placing the material into a
sealed bag or container and throwing it into an outside garbage container.
• inspect spices, pet food, and flower arrangements.
• Once all of the infested material has been removed, be sure to vacuum and clean
up the area around the infestation.
• If you have shelf paper, it would be wise to remove it, thoroughly clean under it
with soap and hot water, and replace it with new paper.
• Be sure to pay close attention to the cracks and crevices of any cabinets.
• To prevent re-infestation, all grain products should be stored in containers with
tight fitting lids, or stored in the freezer.

11. Callosobruchus chinensis
(Pulse beetle)
• The Adzuki bean weevil females
lay their eggs directly on the
surface of the legume singly and
move on to either a different part
of the legume
• The eggs usually hatch after 3–5
days
• New larvae will burrow into the been for
the rest of development.
•The larvae chew tunnels through the bean
until it is ready to pupate.
Pupation takes place in
pupal cells prepared
beneath the seed coat.
Mature adults emerge from the
bean, biting a neat circular exit from
the pod as soon as 25 days after
hatching. The adult beetles live up to
two weeks after emerging from the
pupa

12. Damage
• The Adzuki beetle is a major pest of stored lentils.
• Pod infestation can start in the field before harvest, the
pest thus gaining entrance into storage bins.
• It may cause substantial damage, coming to over 80%
losses in weight and in germination rates.
• Infested seeds are less nutritious and unfit for humans.

13. Management
• Horticultural practices:
Intercropping with cereals and early harvesting of legumes, before pest
attack.
Good store hygiene, including the removal of residues from last season’s
harvest.
Heating seeds to 50ºC for one hour kills the eggs and larvae.
• Plant resistance:
Certain legume varieties with thick, hairy walls are resistant to beetle
infestation.
• Chemical control:
Organophosphates and neem compounds have been used in different
countries.
Many plant extracts and oils were applied with uneven success, as
oviposition deterrents and for beetle control.
• Biological control:
Several parasitoids of the families Braconidae and Pteromalidae attack C.
chinensis in various parts of the world.