Lesser grain borer (Rhyzopertha dominica)

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Lesser grain borer (Rhyzopertha dominica)

Type of pest: Primary pest.

The lesser grain borer, Rhyzopertha dominica, is a cosmopolitan beetle of the Bostrichidae family.

Distribution: Worldwide, especially warm temperate to tropical regions.

Identification: Adults are 3 mm, dark reddish-brown, cylindrical in cross-section. The head is bent downwards and is concealed. The tip of abdomen is tapered, with the end of the elytra curved gradually. Larvae: scarabaeiform, with legs fully developed.

Similar species: Dinoderus, Prostephanus.

Lifecycle: Optimal conditions are 25 days at 34 ÂșC, 70 % r.h. Eggs are laid on the commodity or in tunnels bored by the adults. Larvae are internal feeders producing lots of flour, and are immobile when mature. Adults are long-lived, free and bore into the commodity and can fly.

Commodities infested: It is a very destructive primary pest of stored grains. While it is common in warmer regions, in temperate regions it is confined to buildings. It is one of the most injurious beetles known to attack grain and is more destructive than the rusty grain beetle and granary weevil.

Damage is distinctive and heavy. The lesser grain borer attacks a wide variety of stored foods including cereals, seeds and dried fruit; nearly all grains, especially wheat, barley, sorghum and rice; commodities such as seeds, drugs, cork, wood and paper products. Adults and larvae feed on the germ and endosperm which reduces wheat kernels to shells of bran. They also cause damage by burrowing through the kernel. Signs of infestation include large amounts of flour, tunnels and irregularly-shaped holes in the commodity and a sweet odor in the grain.

Treatment: Controlled Atmosphere for infestation in product
Treatment: Heat Treatment for infestation in buildings