Pea weevil – Bruchus pisorum

Bruchus pisorum

Bruchus pisorum

Distribution:

This species is widespread in all continents and in all regions of the European continent.

Description

The adult has an elongated oval black body, covered with dense, grey-reddish pubescence and is 4-5 mm long.

Bruchus pisorum - adult

The egg is oval, yellowish-white color, 1.5 mm long and 0.6 mm wide. The neonate larva is oligopod, is 1.5-1.6 mm long, with thin legs, the head is brown, and the body is yellow-reddish. The larva of the last age has no legs, is 5-6 mm long, of yellowish-white color. The pupa is free, of yellowish color, 4-5 mm long. 

Bruchus pisorum - larva

Biology and ecology:

It develops a generation per year and hibernates as an adult in warehouses, infested beans, cracks in walls and in floorboards. A part of  adults are hibernating in the field, in infested beans, shaken at harvest, in the cracks of the tree barks or under plant debris.

In late April, when the average daily temperature exceeds 14°C, the adults migrate to crops of peas at distances up to 3 km. The maximum flight is registered at temperatures of 26-28°C, in phenological phase of the pea blooming and they are very active in warm and sunny days, feeding on the pollen of flowers of the pea.

When reaching sexual maturity, the copulation and egg laying occur. The egg laying coincides with the formation of the pods, it begins in late May and lasts approx. 30 days. A female lays 150-200 eggs, which are laid separately on the well-developed beans, on a pod being observed up to 30 eggs.

After an incubation of 8-12 days, the neonate larvae penetrate through the wall of the pod in the beans, where they slough and remain without legs. The development of the larvae takes place inside the beans for 30-45 days. Even if in a bean have entered several larvae, at the complete development gets only one.  

Attacked plants and damage:

The species is considered to be monophagous, the larvae live inside nibble in the interior of the beans of the sides of the stamen, consuming up to 40-50% of their mass. Adults feed with flower nectar.

Bruchus pisorum - affected plant

Bruchus pisorum - affected plant 1

Prevention and control

For treating the stored pea beans, we recommend using insecticides such as: Reldan 20 EC (12.5 ml/t seed), Actellic EC (0.2 l/m² storage space).

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