Grain storage MCQ, with answers.
20 questions on stored grain pests, fumigation, godown practice and food preservation, the warehouse topics in the CWC 2026 technical papers. Pick an answer to see if you are right and why. The full answer key is below the quiz.
Q1. The scientific name of the rice weevil is:
Q2. Trogoderma granarium is commonly called:
Q3. The lesser grain borer is:
Q4. Callosobruchus chinensis is a major pest of stored:
Q5. The Angoumois grain moth is:
Q6. Which of these is a secondary pest that feeds on broken grain and flour?
Q7. Aluminium phosphide tablets used to fumigate grain stacks release which gas?
Q8. Aluminium phosphide releases its gas when it reacts with:
Q9. During fumigation, a grain stack is usually covered with:
Q10. Malathion, used for prophylactic spraying in godowns, is:
Q11. Deltamethrin belongs to which group of insecticides?
Q12. Bromadiolone is used in warehouses as:
Q13. Dunnage is placed under bags in a godown mainly to:
Q14. In grain storage, CAP stands for:
Q15. Aflatoxin in stored groundnut and maize is produced by:
Q16. Wheat is generally considered safe for long storage at a moisture content of about:
Q17. Hermetic (airtight) storage controls insects mainly by:
Q18. Controlled atmosphere storage of fruit works by:
Q19. The water activity (aw) of pure water is:
Q20. HTST pasteurisation of milk uses about:
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Grain storage (CWC) MCQ answers and reasons.
Q1. The scientific name of the rice weevil is:
Answer: A, Sitophilus oryzae. The rice weevil is Sitophilus oryzae, a primary pest whose grub develops inside the grain.
Q2. Trogoderma granarium is commonly called:
Answer: B, Khapra beetle. Trogoderma granarium is the khapra beetle, one of the most serious pests of stored wheat; its hairy grubs do the damage.
Q3. The lesser grain borer is:
Answer: A, Rhyzopertha dominica. Rhyzopertha dominica bores into whole grains, leaving them hollow with fine flour-like dust.
Q4. Callosobruchus chinensis is a major pest of stored:
Answer: C, Pulses. Callosobruchus species are pulse beetles (bruchids); grubs develop inside gram, green gram, cowpea and other pulses.
Q5. The Angoumois grain moth is:
Answer: B, Sitotroga cerealella. Sitotroga cerealella lays eggs on grain and its larva feeds inside the kernel of paddy, maize and wheat.
Q6. Which of these is a secondary pest that feeds on broken grain and flour?
Answer: C, Red flour beetle. The red flour beetle, Tribolium castaneum, cannot attack sound grain; it feeds on broken grain, flour and dust left by primary pests.
Q7. Aluminium phosphide tablets used to fumigate grain stacks release which gas?
Answer: B, Phosphine. Aluminium phosphide reacts with moisture in the air to release phosphine (PH₃), which kills all stages of stored grain insects.
Q8. Aluminium phosphide releases its gas when it reacts with:
Answer: B, Moisture in the air. It reacts with atmospheric moisture, which is why tablets are kept in airtight containers until use.
Q9. During fumigation, a grain stack is usually covered with:
Answer: B, Gas-proof polythene (fumigation) covers. Gas-proof covers sealed at the floor hold the fumigant in the stack long enough to kill the insects.
Q10. Malathion, used for prophylactic spraying in godowns, is:
Answer: A, An organophosphate. Malathion is an organophosphate insecticide used as a surface spray on stacks, walls and floors.
Q11. Deltamethrin belongs to which group of insecticides?
Answer: B, Synthetic pyrethroids. Deltamethrin is a synthetic pyrethroid, used as a residual spray in warehouses.
Q12. Bromadiolone is used in warehouses as:
Answer: B, An anticoagulant rodenticide. Bromadiolone is a single-dose anticoagulant rodenticide used in baits for rat control.
Q13. Dunnage is placed under bags in a godown mainly to:
Answer: B, Stop moisture from the floor reaching the grain. Dunnage (wooden crates, polythene sheets or bamboo mats) keeps bags off the floor so ground moisture does not wet the bottom layers.
Q14. In grain storage, CAP stands for:
Answer: B, Cover and Plinth. CAP (Cover and Plinth) storage keeps bagged grain on raised plinths under polythene covers in the open.
Q15. Aflatoxin in stored groundnut and maize is produced by:
Answer: A, Aspergillus flavus. Aflatoxins are made mainly by Aspergillus flavus and A. parasiticus, which grow on damp, warm stored produce.
Q16. Wheat is generally considered safe for long storage at a moisture content of about:
Answer: A, 10 to 12%. Grain dried to about 12% moisture or below resists moulds and slows insect growth.
Q17. Hermetic (airtight) storage controls insects mainly by:
Answer: B, Lowering oxygen as insects and grain respire. In a sealed bag or bin, respiration uses up oxygen and raises carbon dioxide until insects die.
Q18. Controlled atmosphere storage of fruit works by:
Answer: B, Lowering oxygen and raising CO₂. Low oxygen and higher carbon dioxide slow respiration and ripening, extending storage life.
Q19. The water activity (aw) of pure water is:
Answer: C, 1.0. Water activity runs from 0 to 1; pure water is 1.0. Most bacteria need about 0.91 or more, moulds can grow down to about 0.80.
Q20. HTST pasteurisation of milk uses about:
Answer: B, 72 °C for 15 seconds. High temperature short time pasteurisation is about 72 °C for 15 seconds. 63 °C for 30 minutes is the holding (LTLT) method; 135 °C for 2 seconds is UHT.
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