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Broad Bean Weevil and Pea Weevil

Bruchus rufimanus and Bruchus pisorum

Profile

Field bean and pea weevils are outdoor pests. The larvae eat circular holes in the seeds of field beans and peas, causing damage.

Appearance

The beetles are about 3-5 mm long, blackish, with brown, white-speckled elytra. In the field beetle, the front legs are also reddish, while the middle and rear legs are grey-black. The first four limbs of its antennae are also red. The abdomen has a continuous white hairy area at the rear end. In the pea beetle, the front legs and the first four antennal segments are also reddish. In addition, however, the tips of the rails of the middle legs are reddish and the white hairy area at the rear end of the abdomen has two black spots.

Präparat eines Erbsenkäfers (Enlarges Image in Dialog Window)
Erbsenkäfer
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Erbsenkäfer, hier sind die schwarzen Flecken am Hinterende gut zu sehen
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Erbsenkäfer, hier sind die roten Fühlerglieder gut sichtbar
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Der Ackerbohnenkäfer hat hinten keine schwarzen Flecken
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Ackerbohnenkäfer, sowohl die rötlichen Fühlerglieder, als auch Vorderbeine sind zu sehen.

Biology

Both beetles only produce one generation per year.

They overwinter protected under bark, in windbreaks, between lichens, in the leaf litter or still in the seed itself. At the end of their hibernation, they seek out new pea or bean fields. The females feed there on pea or bean nectar and pollen for their maturing diet.

After mating, the female beetles lay up to 10 eggs on the growing pods. A female field bean weevil can lay around 100 eggs, while the pea bean weevil can lay up to several hundred. The hatched larvae bore into the pods, eat circular holes in the seeds and pupate. Some of the young beetles leave the seeds before the harvest, but some remain in the harvested crop and can colonise the new field when infested seeds are sown again.

Damage symptoms

Damaged seeds have a circular cylindrical hole. If the seed coat has not yet been completely pierced by the beetle, these areas are also recognisable as circular "windows".

Erbsensamen mit Löchern (Enlarges Image in Dialog Window)
Deutliche Löcher, die durch Erbsenkäferlarven in Erbsensamen verursacht wurden. Bei den oberen zwei Erbsen sind Fenster sichtbar.
Erbsensamen mit Löchern (Enlarges Image in Dialog Window)
Deutliche Löcher, die durch Ackerbohnenkäferlarven in Ackerbohnensamen verursacht wurden.

Host plants

The beetles are found on field beans and peas. However, the field bean weevil can also attack other butterfly plants. For example, vetches, sweet peas, lupins and chickpeas.

Distribution

They are increasingly found in regions where peas and field beans are more important crops. Globally, the field bean weevil is found in Europe, Africa and at least parts of North America and Asia. The pea weevil now occurs worldwide.

Spread and transmission

The pest can be spread via seed or harvested produce to regions where it does not yet occur.

Economic significance

The beetles cause feeding damage, which can lead to a loss of germination capacity and an increase in the degree of infestation (especially through infested farm-saved seed). Heavy infestations can also lead to yield losses. The beetles are exclusively outdoor pests and not storage pests such as the edible bean beetle(Acanthoscelides obtectus).

Prevention and control

Services

Plant Health Services

Last updated: 18.10.2024

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