bean weevil

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Related to Pea and bean weevil: Bruchidae, seed weevil, seed beetle

bean weevil,

common name for a well-known cosmopolitan species of beetle (Acanthoscelides obtectus) that attacks beans and is thought to be native to the United States. It belongs to the family Bruchidae, the seed beetles. The bean weevil is small, about 1-6 in. (0.4 cm) long, and stout-bodied, with a short broad snout and shortened wing covers (elytra). The adults attack legumes either in storage or in the field and may even completely destroy them. The grubs, or larvae, hatch from eggs laid in holes that have been chewed by the female into stored beans or into pods in the field. In heavy infestations there may be two dozen or more newly hatched larvae in one bean. When full-grown, the larvae form pupae in the eaten-out cavity. As many as six generations are produced in a single season, and in storage breeding continues as long as there is available food left in the beans and a warm temperature. The larvae can be killed by fumigation or by heating the seeds to 145°F; (63°C;) for two hours. Bean weevils are classified in the phylum ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
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, class Insecta, order Coleoptera, family Bruchidae.

Bean Weevil

 

(Acanthoscelides obtectus), a beetle of the family Bruchidae that infests leguminous crops. The body is oval and measures 2–5 mm in length. The coloration is copper brown, except on the abdomen and the tips of the elytra, which are yellowish red.

Bean weevils appear when the bean plants finish blooming and the pods begin to ripen. They reproduce in the field and in storehouses at a temperature of 13°–31° C. The female deposits the eggs (an average of 45) in clusters in the cracks of dried pods or on or between the seeds. Within four days the larvae move about freely and penetrate the seeds, where they develop, pupate, and become beetles. The developmental cycle of the bean weevil takes 34–60 days, depending on the temperature. Under normal conditions it dies after producing three or four generations.

The bean weevil is found in Western Europe and the USSR, primarily in Transcaucasia, Krasnodar Krai, and the Ukrainian SSR. It infests beans and, to a lesser extent, chick-peas, vetchlings, peas, lentils, broad beans, and soybeans. The damaged seeds are inferior in nutritional value and sowing quality.

Control measures include the sowing of uninfected seeds, the chemical treatment of the plants when the pods are ripening, postharvest plowing, disinfection of storehouses, fumigation of food and seed beans with pesticides, and the refrigeration and freezing of infested beans or the heating of seeds to a temperature of 18° C for 20 minutes.

REFERENCES

Brudnaia, A. A. Bor’ba s vrediteliami zernobobovykh kul’tur. Moscow, 1963.
Zakladnoi, G. A., and V. F. Ratanova. Vrediteli khlebnykh zapasov i mery bor’by s nimi. Moscow, 1973.
A. A. BRUDNAIA