Grain Storage Pests

What are the three main problems associated with storing grain pests?

• Contamination

• Direct yield loss from feeding

• Heat

What defines primary storage insects in grain stores?

They specialise in infesting stored foodstuffs and are not found in crops in the field, causing increased temperature and moisture in the grain which creates the ideal conditions for secondary pests

Which primary storage insects are common in the UK?

• Saw tooth grain beetle (most common)

• Grain weevil

• Rust red grain beetle

• Mites (about 0.5 mm long)

How do secondary storage insects enter grain stores?

They often invade from nearby habitats such as haystacks

Which secondary storage insects commonly appear in grain stores?

• Spider beetle

• Fungus beetle

• Book lice

Why should a grain store be fully sealed and maintained?

A properly sealed store prevents pest entry, helping maintain pest-free conditions and prolonging grain quality.

Why should you not introduce contaminated grain into the grain store?

It will result in further contamination of otherwise clean grain resulting in further problems and more work to rectify - should dispose of instead

Why is storing grain with excess moisture above 15% and in warm temperatures risky?

Moist grain fosters pest and fungal growth, leading to faster reproduction of insects and mites.

Which temperature range is optimal for weevils and beetles in grain storage?

They thrive between 25 and 35 degrees celsius, making temperature control essential.

At what temperature do mites build up most quickly?

Around 20 degrees celsius, so cooling grain below 5 degrees helps suppress mite populations.

How often should stored grain be monitored for changes in temperature and moisture?

Typically weekly, checking different depths to catch early signs of pest activity (higher temperatures and increased moisture would indicate pest activity)

Why is it important to clean the grain store before harvest?

Removing old grain residues and dust via vacuuming reduces the risk of pests contamination before the fresh grain is stored

What is a key benefit of using a dedicated grain store without other machinery?

It reduces the risk of contamination from equipment that may carry pests or debris.

Why should grain not be stored over multiple seasons if possible?

Long storage increases the likelihood of pest buildup and grain deterioration.

What is an alternative to on-farm grain storage?

Selling grain immediately after harvest or paying another facility to store it minimises on-farm pest risks.

Why should you ensure you have enough grain storage capacity?

To ensure all grain can be stored securely and reduce the risk of pest contamination

Why should grain for feed not be stored with harvested grain?

It increases the risk of contamination as the cleanliness of feed grain will be less than that being sold for human consumption

Why must combine settings be carefully adjusted at harvest?

Minimising grain damage lowers vulnerability to insect infestation - intact kernels are harder for pests to access.

How can bait bags and pheromone traps assist before storing grain?

They help detect early pest pressure to allow for corrective actions to be taken before the entire store is filled.

Which physical techniques might control grain pests without chemicals?

Cooling, cleaning, conveying, and drying can collectively suppress insect populations and reduce moisture.

What chemical controls are available for stored grain pests?

Options include ad-mixed insecticides or fumigation, each with specific uses and regulations.

Are ad-mixtures permitted for use in stored OSR?

No - they can only be used on cereals and pulses

Which two ad-mixture insecticides are commonly used in cereal and pulse storage?

• K Obiol EC25 (deltamethrin) - cereals and pulses

• Actellic 50 EC (pirimiphos-methyl) - cereals only

What certification is required by operators to apply ad-mixtures on a specialist application conveyors?

Operators need a PA12 certificate to legally and safely apply these treatments.

How do fumigants kill all pest life stages in static stored grain?

Phosphine gas (from aluminium or magnesium phosphide) permeates the sealed grain mass and eradicates eggs, larvae, and adults in one treatment.

What are the two forms of phosphine gas found in fumigants?

• Aluminium Phosphide (eg: Phostoxin Tablets)

• Magnesium Phosphide (eg: Degesch Plates)

Do fumigants for controlling grain storage pests offer any residual control?

No - they will kill all pest life stages when used but offer no protection going forwards

Why must fumigation be performed by professional servicing companies?

It requires expertise in handling toxic phosphine gas and ensures legal compliance and safety - grain must be sealed for several days

Why should rodenticides be a last resort for controlling rodents in grain stores?

Priority should be given to proofing and securing the building against entry, limiting the need for toxic bait.