Life cycle of the coleopter Bruchidius raddianae and the seed predation of the Acacia tortilis Subsp. raddiana in Tunisia

Seeds of Acacia tortilis (Forsskal) Hayne ssp. raddiana (Save) Brenan, a savannah tree of great potential for forestry and an excellent browse for game and livestock, is heavily infested by the bruchid beetle Bruchidius raddianae Anton & Delobel. The development from egg to beetle, and the various development stages were investigated using Scanning Electron Microscopy (SEM). The adult B. raddianae lays eggs on the green pod in the autumn. The first instar larva hatches from five to seven weeks and develops outside the host seed. From the second instar onwards development took place inside the host seed. Pupation takes about three weeks, late in the summer. The beetle of B. raddianae is univoltine and the newly emerged adult makes an exit hole to leave the seed. During the development from first instar lava to imago, all embryonic tissue is destroyed. This results in a weakness of its soil seed stock, which reduces the possibilities of natural regeneration of the species.