Scientific Name: Caryedon serratus (Olivier)

Common Names: Groundnut bruchid

Synonyms

Pachymerus serratus

Bruchus serratus

Taxonomic Position

Class: Insecta

Order: Coleoptera

Family: Bruchidae

Genus: Caryedon

Species: Caryedon serratus

Host Range

Groundnut, Tamarind, Acasia nilotica, palm kernels, cocoa beans and cotton seed cake.

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

C. serratus infestation of groundnuts is revealed by larval emergence holes and the presence of cocoons outside the pods. Feeding damage to the seeds can be seen when infested pods are split open. 

Identification Features 

Egg

The eggs are translucent, white, oval and 1 mm long and 0.5 mm wide.

Larva

C. serratus larvae are scaribeiform and sparsely hairy. They usually leave the pods of their host before pupation.

Adult

• Body length 3.5-7.4 mm. Entire body is covered dorsally by golden scale-like setae.
• The adult beetle is reddish brown to reddish yellow in color with small black markings on the elytra.
• Antenna is serrate, 11 segmented and longer in male than female.
• Metathoracic femur is well developed with two rows of spines.
• The pygidium is exposed in case of female, while concealed in male.
• It has large prominent eyes and readily distinguished from the other storage pests by its broad hind femur, which bears a conspicuous comb of spines.
• Metafemora strongly thickened, with ventral, comb-like row of one large, sub median tooth followed by 8-12 small teeth.

Life Cycle

• The eggs are laid singly on the pods as well as on the seeds of its hosts or it may stick to the depressions on the shell of the nut or on the smooth testa of the kernels. 
• The incubation period ranges from 6-15 days.
• The larvae are while but turn pink in later stages. The total larval period is 11-49 days depends on the temperature and host.
• The pupation takes place in the papery cocoons and period varies from 13 -23 days.
• The total development varies from 32-142 days. The pre –oviposition period is generally short and varies from 16-19 days.

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.