2. Red flour beetle- Tribolium castaneum {Tenebrionidae
Coleoptera}
Its is one among the bran bugs which damages Broken
grains/ mechanically damaged grains, germ portion
and milled products.
It feeds on cereals, flour, starchy material, fruit nuts,
millets and prepared cereal foods. It usually feed on broken
grains and results in dust formation.
Worst pest of mill machinery
Also important pest in commercial Corcyra production
units
COSMOPOLITION , origin is believed to be south Asia
3. Biology of RFB
Egg : Freshly laid eggs were very small, whitish,
cylindrical microscopic and often have bits of flour
stuck to their surface and harden, making them
difficult to see. The incubation period ranged from 4
to 7 days.
Grub : Elateriform with urogomphi and minute hairs all
over the body. 30 to 40 days { 6 instars}
pupa: Exarate type .5-9 days 8 { male 6-7 days and
female 7-9 days}
5. Adult
The adult red flour beetle is
approximately 3-4 mm long with a
flattish curved-sided body which is
reddish-brown in colour. The head
and upper part of the thorax are
covered with minute punctures and
the wing cases (elytra ) are ridged
along their length. They can fly.
Antenna have an abrupt 3
segmented club at distal end
6. Damage symptoms
Adult and grubs causes damage .
They highly prefer broken grains
and flour and can damage some
intact seeds. Eg; sesame
Adults constructs tunnels as
they move through flour
They produce quinine
substances and thus the infected
flour can be easily identified
with acidous odour .
7. Gaseous quinines
They produced compounds like
2-ethyl-1,4 benzoquinone
2-methyl 1,4 benzoquinone
2 methoxy 1,4 benzoquinone
These compounds on inhaling continously causes
several respiratory problems like bronchitis skin
irritation , redness of eyes and when consumed causes
abdominal pain, burning sensation.
{International Iabour Organization}
8. Flour conditioning and cannibalism
in RFB
As the beetles startes to feed , nutrition quality of flour
reduces, flour is now filled with feacal matter ,
quinone derivatives ,and exuvia . This process is called
flour conditioning.
RFB exhibits cannibalism , active stage feeds on inactive
stages
9. Effect of flour conditioning and
cannibalism {Earlier findings}
Flour conditioning is a result of depletion of nutrients and
the build up of waste materials, pheromones, and ethylquinone, which is a repellent
produced by the beetles (Sonleitner 1961)
Sonleitner (1961) showed that egg cannibalism in adult T. castaneum increased in
conditioned flour compared with fresh flour.
Cannibalism is directly proportional to flour conditioning
10. Later findings
Adult male - cannibalism level was low
Grub – cannibalism increased slightly as flour conditioning
increased
Female : cannibalism is inversely proportional to flour
conditioning
Since females didn’t prefer to dig the conditioned flour and
quinines acts as repellent to females
To conclude
Conditioned flour acts as a ovipositional deterrent and protected
existing beetle from unwanted visitors
Females prefer to lay eggs on fresh flour
