Acanthoscelides obtectus | |
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Scientific classification ![]() | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Coleoptera |
Family: | Chrysomelidae |
Genus: | Acanthoscelides |
Species: | A. obtectus |
Binomial name | |
Acanthoscelides obtectus (Say, 1831) | |
Synonyms | |
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Acanthoscelides obtectus, the bean weevil, is a species of bruchid beetle. The species was described in 1831 by Thomas Say. [1]
Bean weevils feed primarily on the seeds of common beans but also feed on the seeds of peas, vetches, and many other leguminous plants. They have also been reported to develop on the seeds of a few non-legumes, such as maize and buckwheat. [2] Bean weevils are pests of legume seeds both in field and in storage. Only the larvae feed on seeds: the adults feed on pollen.
Originating in mountainous regions of northern South America, its has been inadvertently introduced to Central America, then around the world in grain shipments. [3]
American naturalist Thomas Say described the bean weevil species as Bruchus obtectus in 1831, [1] and was later moved to the genus Acanthoscelides. [4] In a 1870 publication John Lawrence LeConte mistakenly called it Bruchus obsoletus , which led several later author to call it under this name which in fact belonged to another species, and as a result references to A. obtectus in publications from the late 1800 and early 1900 often used the incorrect name Bruchus obsoletus. [5]
Bean weevils are small beetles, ranging in size from 2 to 5 mm. [6] They range in colour from light to dark brown, with longitudinal spots on their elytra, which has a red posterior border. Eleytra does not cover the abdominal end. Legs are yellow red and antenna red brown. [6] [7] The head is bent forward and lacks the long snout that is characteristic of true weevils. [8]
Eggs are milky white. Larvae are white with a yellow head during their first instar and white with a brownish head from the second instar. Larvae have bristles and three pairs of legs. [6] [7]
Bean weevils develop and feed upon leguminous plants. Adult bean weevils hibernate inside the seeds or seed pods of these plants. [7] Adults emerge from hibernation in April to mate. [7] Female bean weevils lay eggs onto seed pods, or into them by chewing holes, in groups of 2 to 20 eggs. [6] [7] A single female can lay up to 200 eggs. [6] but 40 is average fecundity. [7] Egg development can take 30 to 45 days before a 1st instar larvae merges. After approximately 3 days the larvae then moults and becomes a second instar larvae which then begin to consume the seed, with the larval stage lasting 3 to 3+1⁄2 weeks in total. [7] The larvae then pupates inside the seed, taking 9 to 29 days. [6] The life cycle of a single generation takes from 100 to 110 days. If the seeds are stored in a warm place multiple generations can be produced one after another. [7]
Bean weevils are originally native to northern South America, [3] however grain shipments at the end of the 19th century introduced the species to Europe where it subsequently spread around the globe. It is now found in Europe, Asia, North and South America, Africa, Australia and elsewhere. [6] [9]
The species favours warmer climates, with the most favourable temperatures being 27–29 °C for adults, 24–27 °C for larvae, and 22–26 °C for pupa. Temperatures higher or lower than this can cause a decrease in the number of eggs laid and they are very vulnerable to temperatures below 0 °C. This limits the species to how far north it can spread, and is found only as far north as northern Lithuania, with some being found in south-west Siberia. [6]
A number of parasitoid wasps are associated with the bean weevil larvae. [10]
The bean weevil is a significant pest in some parts of the world, especially in areas such as Australia where it is non-native. [8] It damages crops both in situ and when stored in warehouses, and can potentially reduce crop yields by 60% [6] as the larvae develop at the expense of the seeds. [7]
The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle families. Numerous subfamilies are recognized, but the precise taxonomy and systematics are likely to change with ongoing research.
The bean weevils or seed beetles are a subfamily (Bruchinae) of beetles, now placed in the family Chrysomelidae, though they have historically been treated as a separate family. They are granivores, and typically infest various kinds of seeds or beans, living most of their lives inside a single seed. The subfamily includes about 1,650 species and are found worldwide.
The drugstore beetle, also known as the bread beetle, biscuit beetle, and misnamed as the biscuit weevil, is a tiny, brown beetle that can be found infesting a wide variety of dried plant products, where it is among the most common non-weevils to be found. It is the only living member of the genus Stegobium. It belongs to the family Ptinidae, which also includes the deathwatch beetle and furniture beetle.
The Mexican bean beetle is a species of lady beetle that can be an agricultural pest. It is one of the few North American lady beetles that feed on plants rather than other insects. It is found throughout Mexico and the eastern United States, and is abundant in the wetter and more heavily irrigated areas west of the Rocky Mountains. It does not tolerate extremely dry areas.
Bruchidius villosus is a species of bean weevil known by the common names broom seed beetle and Scotch broom bruchid. This beetle is used as an agent of biological pest control against the noxious weed known as Scotch broom.
Callosobruchus maculatus is a species of beetles known commonly as the cowpea weevil or cowpea seed beetle. It is a member of the leaf beetle family, Chrysomelidae, and not a true weevil. This common pest of stored legumes has a cosmopolitan distribution, occurring on every continent except Antarctica. The beetle most likely originated in West Africa and moved around the globe with the trade of legumes and other crops. As only a small number of individuals were likely present in legumes carried by people to distant places, the populations that have invaded various parts of the globe have likely gone through multiple bottlenecks. Despite these bottlenecks and the subsequent rounds of inbreeding, these populations persist. This ability to withstand a high degree of inbreeding has likely contributed to this species’ prevalence as a pest.
Caryobruchus gleditsiae is a species of beetle in the family Chrysomelidae. It lives in North and Central America and develops inside the seeds of palm trees. Adults grow to a maximum length of 11 mm (0.43 in), the size depending on the size of the seed it grew up in. The species was first described by Carl Linnaeus in his 1763 Centuria Insectorum.
The Epilachninae are a subfamily of the family of lady beetles, the Coccinellidae, in the order Coleoptera. Superficially, they look much like other ladybirds in the larger subfamily Coccinellinae, but they differ importantly in their biology, in that the members of the subfamily are largely or completely leaf-feeding herbivores rather than being predators. Accordingly, several members of the subfamily are crop pests, and sometimes cause locally serious crop losses.
Acanthoscelides is a genus of bean weevils of the subfamily Bruchinae. They are native to the New World. About one third of them can be found in Mexico.
Bruchus is a genus of beetles in the leaf beetle family, Chrysomelidae. They are distributed mainly in the Palearctic, especially in Europe. Several occur in other parts of the world, such as North America, Africa, and Australia, as introduced species. Several species are notorious agricultural pests.
Callosobruchus chinensis is a common species of beetle found in the bean weevil subfamily, and is known to be a pest to many stored legumes. Although it is commonly known as the adzuki bean weevil it is in fact not a true weevil, belonging instead to the leaf beetle family, Chrysomelidae. Other common names include the pulse beetle, Chinese bruchid and cowpea bruchid. This species has a very similar lifestyle and habitat to Callosobruchus maculatus and their identities are often mistaken for each other. This beetle is a common pest targeting many different species of stored legumes and it is distributed across the tropical and subtropical regions of the world. C. chinensis is one of the most damaging crop pests to the stored legume industry due to their generalized legume diets and wide distribution.
Tribolium is a genus of flour beetles in the family Tenebrionidae. They are known by various common names including flour beetles, flour weevils, red weevils and bran bugs.
Bruchus rufimanus, commonly known as the broadbean weevil, broadbean beetle, or broadbean seed beetle is a leaf beetle which inhabits crops and fields, as well as some homes. It is a pest of faba beans. The adult beetles feed on pollen, while their larvae tunnel in seeds destroying crops and moving on to new ones once they dry out. The adult beetle, being one of the biggest of its genus, ranges from 3 to 5 mm in length.
Callosobruchus is a genus of beetles in the family Chrysomelidae, the leaf beetles. It is in the subfamily Bruchinae, the bean weevils. Many beetles in the genus are well known as economically important pests that infest stored foodstuffs.
Euthyrhynchus floridanus, the Florida predatory stink bug, is a species of carnivorous shield bug in the family Pentatomidae, the only species in the genus Euthyrhynchus. It is native to the hottest parts of the southeastern United States and is considered beneficial because it feeds on many species of pest insects. They also feed on things such as grasshoppers and other small insects. This species also hunts in a pack, with up to twelve.
Hypera nigrirostris, commonly known as the lesser clover leaf weevil, is a species of weevil that is native to Europe and northern Africa and has been introduced to North America and Japan. Both adults and larvae feed on red clover and other plants in the family Fabaceae.
Sitona lineatus, commonly known as the pea leaf weevil is a species of weevil with a Palearctic distribution. It is a common pest of beans, peas, and other plants in the family Fabaceae. Adult beetles of S. lineatus measure 3.4-5.3 mm in length. They are characterized by a series of colored scales arranged in alternating lines (striae) on the elytra; it is from this characteristic where the species gets its name lineatus meaning 'lined' or 'striped'. The head and pronotum also have fine pointed setae amongst the scales. The antennae are clubbed, pointed and preceded by 7 segments. The femora is dark, but tibiae and tarsi are red. As a member of Order Coleoptera (beetles) their forewings are modified to form hardened covers over the thorax and abdomen, with the hindwings for flight underneath.
Bruchus pisorum, known generally as pea weevil, is a species of leaf beetle in the family Chrysomelidae. Other common names include the pea beetle and pea seed beetle. It is found in Europe and Northern Asia, North America, and temperate Asia.
Clavigralla gibbosa, the tur pod bug, is a species of leaf-footed bug in the family Coreidae. It is found in India, Sri Lanka and Myanmar, where it is a pest of pigeon pea.
Acanthoscelides obvelatus is a species of bean bruchid occurring in Mexico, Central America, and northern South America. It and the bean weevil, Acanthoscelides obtectus, are sibling species and occur sympatrically throughout A. obvelatus' range. Both species are morphologically very similar and as a result, A. obvelatus has been confused with A. obtectus by several authors. The most notable difference between the two species is that A. obtectus is multivoltine and apparently does not diapause, while A. obvelatus is univoltine and has an obligatory imaginal diapause. Due to this fact, unlike A. obtectus, A. obvelatus is not a pest of stored beans. However, both species can be pests of beans in fields. The main morphological differences between the two species are: the color of the pygidium, femur, and apical antennal segment, which are orange in A. obtectus but brown-black in A. obvelatus; as well as the shape of the antennae, which have longer and thinner segments in A. obvelatus. The most reliable character is only found in males and concerns the shape of lateral lobes of the aedeagus, which are smooth and thin in A. obtectus but sclerified and thick in A. obvelatus.