2. • Sitophilus oryzae
• major pest in stored grain products like rice,
maize (मक
ै ), sorghum(ज्वारी), corn, barley(जौ)
and wheat (गहुँ)
• grow in humid conditions with moderately high
temperature
• larval and adult stages of rice weevils damage
the stored grain products. Thus, knowledge on
its morphology, life cycle is required to know
about infested products and possible control
measures is vital in overcoming the damage
caused by rice weevil.
INTRODUCTION
4. Habit and Habitat
• Rice weevil originated from India and most tropical parts
of the world.
• one of the most destructive primary pests of stored
cereals. Female use strong mandibles to chew a hole into
a grain kernel after which she deposits a single egg within
the hole, sealing it with secretions from her ovipositor.
• gather on the corner of home, cracks and gaps that lead
inside.
• They are attracted to light and can fly
5. Morphology
•Size is around 3 mm
•The color ranges from reddish
brown, chocolate to almost
black
•The snout is long almost one-
third of its total length
• The larvae are soft, white grubs
with no legs.
•Pupae are similar to adults with
long snouts, but they are white.
6. Morphology
• Body divided into
• Head (6 segments) –
Chewing type of mouthpart
• Thorax (3 segments)
Prothorax is strongly pitted and
elytra have rows of pits within
longitudinal grooves
• Abdomen( 11 segments)
7. Nature of Damage
• Rice weevils are not known to transmit any diseases to
humans.
•However, They are dangeroud to the grain industry and can
cause a lot of problems for homeowners by contaminating
food sources.
•Enter homes through products purchased at the store that
are already infested with adult rice weevils or their larvae.
•mainly caused by two stages of this insect
•(1) Larvae
•(2) Adult
8. Nature of Damage
• Adults feed on whole seeds or flour. Larvae develop in seeds or
pieces of seeds or cereal products large enough to house larvae,
but will not develop in flour unless it has been compacted.
• Indicators of a rice weevil infestation are;
-Increased moisture levels and heating on the surface
-Seeds with round holes formed by exiting adults
9. Nature of Damage
Rice weevils are the most destructive pests of stored grain and they
completely destroy the grain.
Attack is evidenced by,
• Surface heating of grain
• Dampness which may even cause germination
• Presence of numerous adults
10.
11. Control of Rice Weevil
•The fastest, safest, and most effective way to eliminate rice weevils
or any other stored product pest from your home is to get help as
quickly as possible from a professional.
Cultural Practices
dispose of heavily infested foods in wrapped, heavy plastic bags or in
sealed containers for garbage removal, or bury deep in the soil.
Be sure to store only clean, dry grain with a moisture content of 12
percent or less to reduce weevil problems.
12. •Temperature control
Temperature control can also be used to control the rice
weevil. Freezing infected food below -17.7°C (0°F) for
three days retards the growth and development of
various stages of the insect life cycle. Heating to 60°C
(140°F) for 15 minutes destroys all development stages of
rice weevil.
Chemical Control
Application of Insecticides such as Novacide.
Vinegar is effective against rice weevils.
13. Fumigation ( methyl bromide and phosphine as gaseous pesticides)
Adding Dry Ice
14. Life Cycle of Rice Weevil
• Consists of Four Stages
Egg
Larva
Adult
Females start laying eggs
5 days after emergence
Females drill a tiny hole
in the grain kernel,
deposit an egg in the cavity,
then plug the hole with
a gelatinous secretion.
15. Life Cycle of Rice Weevil
Egg
4 eggs per day
• Total of 250-400 eggs
• minute,
• white,
• translucent
• 0.7x0.3 mm in size
• Legless
16. • Pupa
• eggs after completion of incubation period of 5-8
days hatches into young larva
• White, black hard head
• Movable segments
larva shows four instars