Bruchidius terrenus

Albizia seed beetle

Description

Bruchidius terrenus is a seed beetle native to the East Palearctic region that has spread to Europe and North America. It is monophagous, primarily developing in the seeds of the mimosa or silk tree Albizia julibrissin and occasionally Albizia kalkora. Albizia spp. originates from Asia and is widely cultivated in Europe, particularly in the Mediterranean region, as an ornamental tree. The beetle has also been recorded on Robinia pseudoacacia and Acacia confusa. Adult beetles measure 2.46–4.07 mm, with most individuals being 3.7–3.8 mm long. This species has been found in regions such as Crimea, Russia, Bulgaria, and southern USA.

The larvae develop within the seeds of Albizia julibrissin, consuming the seed content and pupating inside. Infestation rates can reach up to 70-80%, significantly reducing seed viability. While B. terrenus does not directly harm the vegetative parts of the tree, heavy seed infestation limits the tree's reproductive success, potentially affecting its ability to spread and thrive in the ecosystem.

Symptom

Infested seed pods display small circular exit holes from which adult beetles emerge. The seeds inside are hollowed out, often with visible frass. Pods may appear shriveled or damaged.

Tree Species: Black Locust, Silk tree

Part of a plant- attacked: Fruit / Seed

Pest significance: Harmful

Pest Category: Insects

Invasive Species: Yes

Present in EU: Yes