Scientific Name: Bruchus pisorum Linnaeus, 1758

Common Name: Pea weevil

Synonyms

Bruchus cruciger, Bruchus pisi, Bruchus salicis, Callosobruchus pisorum, Dermestes pisorum, Laria pisorum, Mylabris pisorum

Taxonomic Position

Class: Insecta

Order: Coleoptera

Family: Bruchidae

Genus: Bruchus

Species: Bruchus pisorum

Origin and Distribution

B. pisorum has a cosmopolitan distribution, with a preference for tropical, subtropical and warmer parts of temperate zones. In some northern parts of the northern hemisphere, it is only reported in imported samples of infested pea. It is widely distribute in India.

Host Range

Pisum sativum (Pea)

Pest Destructive Stage

Primary pest

Eggs –laid or stuck individually onto seed or pod

Larvae – immobile, concealed within seed

Adults – do not feed on commodity, fly readily

Damage Symptoms

Infested stored seeds can be recognized by the eggs on the seed surface and the round exit holes with the ''flap'' of seed coat. The round exit hole and white eggs on the pod/seed wall are conspicuous. Damage shows in the circular holes or "windows" left in the seed when bruchids emerge. Adults are small brown beetles with light bands and markings on their backs. The larvae, which responsible for the major damage are small, white, C-shaped worms with darker heads. To locate them, split open the dried bean pods. Then, select seeds with minute holes that appear drilled to the inside. Cut these open to expose larvae feeding internally.

Identification features

Egg

The eggs are yellow/orange, cigar-shaped and measure 1.5 mm by 0.6 mm.

Larva

The larva is 'C'-shaped, up to 6 mm long at maturity, legless, thick-bodied, wrinkled, brown-headed, and white to cream. When hatching from the egg, the larva has six thoracic legs, but these disappear after the first moulting.

Pupa

The pupa is 'libera', cream, and about 5 mm long.

Adult

• The adult is an oval, chunky beetle, about 5 mm long.
• It has a triangular pronotum (top plate-like segment on middle body part), small head, 11-segmented antennae arising in front of the eyes, and shortened wing covers exposing the tip of the abdomen.
• It is brownish, flecked with white, black, with grey patches covered with short hairs or scales.
• The tip of the abdomen is exposed behind the wing covers and is white, marked with two black oval spots. There is a visible white cross mark.
• The head is without an obvious beak.
• The legs are black with a large tooth on the upper margin of the hind femur and usually a small tooth on the lower margin.

Detection methods

Samples can be examined with naked eye or under magnifying glass or stereoscopic binocular microscope and by using soft X-ray and seed transparency method hidden infestation can be detected.