A manual of rice seed health testing - IRRI books - International Rice ...

Red flour beetle or bran bug
Scientific name: Tribolium castaneum
(Herbst)
Common name: red flour beetle or bran
bug
Quarantine status: primary pest
Stage of entrance or attachment to
seed: adult, larva, and egg
The body of the adult is 3-5 mm long
and shiny red brown to blackish
brown. It may be confused with the
confused flour beetle. The red flour
beetle’s diagnostic features are a
relatively flat body with a broaderthan-long
pronotum, and parallelsided
abdomen; 11-segmented antennae
with a 3-segmented pronounced
club; a head lacking a ridge
above the eyes; and eyes separated
ventrally by a space less than two
times the diameter of the eye. The
adult lives 335-540 d.
Each female lays 300-500 eggs on
the outside of grains, attaching the
eggs with sticky glue.
Larvae feed both outside and inside
the grain. The larva has a
prominent head, three pairs of distinct
legs, forked abdomen tip, and
an elongated and cylindrical white
body tinged with yellow. The life
cycle of the red flour beetle lasts
4-6 wk but may decrease to 20 d under
optimum conditions.
The length of the life cycle depends
on the availability of food.
The pest is omnivorous and cannibalistic.
It is more cold-susceptible
than the cold-hardy Cryptolestes. The
adult is a strong flier.
Confused flour beetle
Scientific name: Tribolium confusurn
(Jacquelin du Val)
Common name: confused flour beetle or
bran bug
Quarantine status: primary pest
Stage of entrance or attachment to
seed: adult, larva, and egg
The adult beetle is 3-4 mm long and
shiny reddish brown. It may be confused
with the red flour beetle. Diagnostic
features include a flat, ovalshaped
body; 11-segmented antennae
gradually thickening toward the
apex, forming a poorly differentiated
5-segmented club; a head with a
ridge above the eyes; and eyes
separated ventrally by a space three
times the diameter of the eye. The
adult lives 1 yr.
Females lay 450-500 eggs on grain.
Larvae feed externally on the grains.
Larvae have prominent heads, the
pairs of distinct legs, forked abdomen
tips, and are pale yellow. The
life cycle is 4-6 wk.
The confused flour beetle prefers
to feed on the grain embryo but can
complete development exclusively
on seedborne fungi. It is more coldhardy
than the red flour beetle and is
a weak flier. Both adults and larvae
are omnivorous and cannibalistic.
Insect pests 73