Peanut bruchid (groundnut bruchid)

The peanut bruchid (Caryedon serratus) is a small coleopteran. Adult (imago): 6–8 mm long, 3–5 mm wide; overall reddish‑brown integument. Nocturnal, it shelters by day in interstices and crevices. Larva: a plump, arcuate white grub with a contrasting brown head capsule, developing within the pods and seeds of legumes.

In storage, females oviposit on pods or kernels; neonate larvae perforate the pericarp and testa, then tunnel through cotyledons and the embryo. Kernels are hollowed and converted to powdery frass, leaving round emergence holes and fragile, shriveled seeds with detached seed coats. Quantitative loss is severe—typically 60–80% reduction in dry seed weight—accompanied by sharp declines in oil yield, rancidity, off-odors, and loss of germination. Pod and seed perforations breach natural barriers, enabling secondary infestations by other stored-product beetles and promoting colonization by mycotoxigenic molds, notably Aspergillus flavus, with consequent aflatoxin contamination. Infestations propagate within stacks and bags, with continuous post-harvest damage under warm, dry conditions unless lots are quickly disinfested and sealed.

Signs of Peanut bruchid (groundnut bruchid), Caryedon serratus, in stored peanuts/legumes: - Round, clean‑edged emergence holes in pods or seeds (perforated testa). - Fine, powdery frass (grain dust) inside bags, at seams, and under stacks. - Oviposition evidence: glued eggs on pod/seed surfaces; within kernels, C‑shaped apodous larvae, pupal cells, and cast exuviae. - Adults present: small mottled‑brown bruchids with patterned elytra, active when disturbed. - Seed quality loss: hollowed or spongy kernels, cotyledon tunneling, weight loss, shriveling/discoloration, reduced germination and oil quality. - Off‑odors (musty/rancid) from lipid‑rich kernels undergoing deterioration. Secondary cues: localized heating, moisture spots, excess fines on screening, and a higher proportion of broken seeds.

Peanut bruchid (Caryedon serratus) is a holometabolous seed borer. Females oviposit white, ovoid eggs on groundnut pods; fecundity may reach ~650 eggs under favorable conditions. Embryonic development is ~7 days. Upon eclosion, neonate larvae bore through the pod wall and enter the seed, feeding endophytically. Larval development lasts a little over one month. The mature larva spins a cocoon and pupates within the seed; the pupal stage lasts ~15 days. Egg‑to‑adult development takes about two months. Adults live 9–11 weeks.

Caryedon serratus prefers warm, dry stored-grain environments, especially warehouses and silos with groundnuts. It thrives in intact or cracked pods under low ventilation, exploiting bulk storage to oviposit and develop within seeds.

Caryedon gonagra: Caryedon “knee-gout” (gonagra = gout of the knee). Caryedon lagonychus: Caryedon “hare-clawed” (Greek lagos = hare + onyx/onych- = claw). Caryedon furcatus: Caryedon “forked.” Caryedon truncatus: Caryedon “truncated” (cut off squarely at the end). Caryedon foveolatus: Caryedon “pitted” (with small pits; foveolate).