Caryedon serratus

Distinguished from other stored-product bruchids by its association with groundnut pods and seeds rather than pulses or grains. Adults can be separated from related bruchid genera by genitalic and external morphological characters typical of Caryedon. The species' broad host range among Caesalpinioideae legumes and its pantropical distribution help differentiate it from more geographically restricted bruchid pests. Specific identification requires examination of male genitalia and comparison with reference specimens.

Adults are small beetles with mean length of 4.10 mm and breadth of 3.40 mm. Eggs measure approximately 0.58 mm in length and 0.15 mm in breadth. Larvae (grubs) pass through four instars with mean lengths of 0.69, 1.27, 2.52, and 3.58 mm and breadths of 0.35, 0.86, 1.35, and 2.10 mm respectively. Pupae measure approximately 4.60 mm in length and 3.00 mm in breadth. The grub stage is the primary damaging form, feeding internally within seeds.

Primarily associated with stored groundnut seeds and pods in agricultural settings. In natural environments, occurs in savanna ecosystems where it develops on seeds of wild leguminous trees such as Piliostigma thonningii. Laboratory studies indicate optimal performance at temperatures of 30-35°C and relative humidity of 60-65%, though the species tolerates a wider range of conditions.

Pantropical and subtropical distribution including Africa, the Caribbean, Europe and Northern Asia (excluding China), Central America, North America, Oceania, and South America. Specific populations studied include the Gambia River region, Lamto savanna in Ivory Coast, Ganye area in Adamawa State Nigeria, and Akola region in India.

In West African savanna conditions, exhibits 2-3 generations per year with first generation developing on maturing seeds at the beginning of the dry season, and subsequent generations developing in dry seeds. Adults enter a semi-lethargic state during the rainy season with no pupal diapause. Under constant laboratory conditions of 25-30°C, continuous breeding occurs on stored groundnuts.

Specialized seed predator feeding on seeds of Fabaceae, subfamily Caesalpinioideae. Primary agricultural host is groundnut (Arachis hypogaea). Natural hosts include Piliostigma thonningii and potentially other leguminous trees. Larvae feed internally within seeds, with the grub stage lasting approximately 14-33 days depending on temperature.

• Arachis hypogaea - primary agricultural hostGroundnut; main stored product host causing economic damage
• Piliostigma thonningii - natural hostWild Caesalpinioideae tree in West African savanna; seeds support 2-3 generations annually

Complete metamorphosis with egg, larval (grub), pupal, and adult stages. Egg incubation: 3-7 days depending on temperature (3-4 days at 30°C/60% RH, 4-5 days at 35°C/65% RH, 6-7 days at 40°C/70% RH). Larval period: 14-23 days (19-23 days at 30°C/60% RH, 14-18 days at 35-40°C with 65-70% RH). Pupal period: approximately 13.5 days. Adult longevity: 12-13.5 days under laboratory conditions; total life period 48-76.5 days with females generally living longer than males. Total life cycle duration: 33-40 days at 30°C/60% RH, 14-18 days at 35°C/65% RH, and 16-20 days at 40°C/70% RH. Pre-oviposition period in females: approximately 1.5 days; oviposition period: approximately 5.5 days.

Females deposit eggs on or near host seeds. Larvae bore into seeds and feed internally, completing development within a single seed. Adults are capable of flight and disperse to new host patches. Under natural savanna conditions, adults enter a semi-lethargic state during the rainy season, resuming activity in the dry season. The species has been observed to develop resistance to pesticides after approximately 10 years of exposure.

Seed predator that reduces seed viability of host legumes. In natural savanna ecosystems, acts as a population control agent for Piliostigma thonningii. Serves as host for a complex of parasitoid wasps including Uscana caryedoni (egg parasitoid), Anisopteromalus caryedophagus, Bracon sp., Proconura serratocida, and Eurytoma caryedocida, contributing to local food web structure.

Major pest of stored groundnuts causing significant post-harvest losses in tropical and subtropical regions. Infestations have been documented at transit crossings and storage facilities, particularly near the Gambia River. Management historically involved Lindane and Malathion, though resistance development has necessitated alternative approaches including phosphine fumigation under plastic sheeting. Essential oils and botanical extracts have been investigated as potential control agents. The species' response to various host plants and botanical compounds has been studied to develop integrated pest management strategies.

• Callosobruchus spp.Other bruchid pests of stored legumes; distinguished by primary host associations (pulses and grains vs. groundnuts) and geographic distribution patterns
• Acanthoscelides obtectusCommon bean bruchid with overlapping distribution; differs in host specificity and morphological characters of adults and larvae

• bruchid
• stored product pest
• groundnut pest
• seed predator
• pantropical

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Biology of Groundnut Bruchid Caryedon Serratus (Olivier)
• Response of Caryedon serratus (Oliver) (Bruchidae: Coleoptera) towards Various Botanicals and Hosts
• Caryedon serratus and its parasitoids in the Savanna around Lamto, Ivory Coast
• A comparative study of some aspects of the reproduction of three Caryedon serratus strains in presence of its potential host plants
• Study on the biology of groundnut bruchid, Caryedon serratus Olivier [Coleoptera: Bruchidae] on stored groundnut in Ganye area, Adamawa State, Nigeria
• Egg-Laying Behaviour of Caryedon serratus (Olivier) on the Essential Oils of Skimmia anquetilia
• Effect of Temperature and Humidity on the Biology and Morphometric Measurement of Groundnut Bruchid (Caryedon serratus Olivier) [Coleoptera: Bruchidae] in Groundnut Seed