Callosobruchus

Pic, 1902

bean weevils, seed beetles

Species Guides

3

Callosobruchus is a of seed beetles in the Chrysomelidae, Bruchinae. The genus contains at least 20 , many of which are economically significant pests of stored legumes. Species specialize on legumes of the tribe Phaseoleae, including mung bean, cowpea, adzuki bean, and common bean. Native to Asia, they occur throughout warm regions of the Old World and have been introduced to other areas through international trade. do not require food or water to reproduce, enabling rapid growth in storage facilities.

Callosobruchus by (c) limbatus, some rights reserved (CC BY). Used under a CC-BY license.Callosobruchus maculatus by (c) Raven Dandridge, some rights reserved (CC BY), uploaded by Raven Dandridge. Used under a CC-BY license.Callosobruchus chinensis by Simon Hinkley & Ken Walker, Museum Victoria. Used under a CC BY 3.0 au license.

Pronunciation

How to pronounce Callosobruchus: /kəˌloʊsoʊˈbruːkəs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Small beetles with compact, somewhat rounded bodies typical of Bruchinae. are serrate or pectinate. Identification to level requires examination of genitalia and other subtle morphological features. Distinguished from other bruchine by specific combinations of antennal structure, pronotal shape, and male genital armature. Species-level identification is challenging and often requires taxonomic knowledge.

Images

Habitat

Stored legume products; warm tropical and subtropical regions. Found in warehouses, grain storage facilities, and agricultural settings where legume seeds are stored. Naturally associated with wild and domesticated legumes in warm regions of the Old World.

Distribution

Native to Asia; occurs in warm regions throughout the Old World. Established as introduced in many areas outside native range through commercial trade in legumes. Present in Africa, Asia, and parts of Europe and the Americas where legume storage occurs.

Seasonality

Year-round activity in storage conditions; in field settings, activity correlates with legume harvest and storage periods.

Diet

Specialized on legume seeds of tribe Phaseoleae. plants include mung bean (Vigna radiata), adzuki bean (Vigna angularis), rice bean (Vigna umbellata), cowpea (Vigna unguiculata), Bambara groundnut (Vigna subterranea), pigeon pea (Cajanus cajan), lablab (Lablab purpureus), and common bean (Phaseolus vulgaris). Also infests peas, lentils, chickpeas, and peanuts.

Life Cycle

Complete with , larval, pupal, and stages. Females lay eggs on legume seeds. Larvae develop inside seeds, consuming the cotyledons. occurs within the seed. Adults emerge through circular exit holes. Development time varies with temperature and . Some species, notably C. maculatus, can complete entire without adult feeding or drinking.

Behavior

Females exhibit oviposition targeting legume seeds, often showing preference for specific . of some species display death-feigning () as anti- behavior; frequency and duration of this behavior decrease with increasing ambient temperature. Males of C. maculatus possess genital spines that injure females during copulation, and females exhibit kicking behavior during mating. Asymmetric mating behavior occurs between some species: male C. maculatus will copulate with C. rhodesianus females due to shared components, but male C. rhodesianus do not reciprocate.

Ecological Role

Pest of stored agricultural products; significant economic impact on legume production and storage. In natural , associates with wild legumes, though ecological role in undisturbed is poorly documented.

Human Relevance

Major economic pest of stored legumes worldwide. reduce seed viability, nutritional value, and marketability. C. maculatus and C. chinensis are particularly destructive, capable of infesting 100% of stored seeds. Control relies on chemical , though and nano- show promise as alternatives. Subject of extensive research in reproductive due to documented sexual conflict and .

Similar Taxa

  • BruchusSimilar seed beetle in Bruchinae; distinguished by antennal structure and male genital
  • AcanthoscelidesAnother bruchine with overlapping associations; requires examination of pronotal and elytral features for separation

Sources and further reading