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