Evaluation of Damage Caused by Bruchids (Coleoptera: Bruchidae) on Peas (Pisum sativum L.)

The effect of bruchids (Coleoptera: Bruchidae) attack on the germination ability of pea seeds (Pisum sativum L.) and on the subsequent seedling vigour was evaluated. Bruchids found in the pea samples studied were all Bruchus pisorum (L.). The parasitoids Triaspis thoracica Curtis and Bracon sp. (Hymenoptera: Braconidae) were also detected in the samples. Attacked seeds tested were those showing a bruchid emergence hole. The proportion of germinated seeds was significantly higher for non-attacked seeds in comparison to attacked seeds. At the end of the assays the non-germinated seeds were extracted from the substrate: all attacked seeds were rotten, without any possibility of later germination, as opposed to non-attacked seeds. Mean weight and mean height of seedlings resulting from non-attacked seeds were significantly greater than those of seedlings resulting from attacked seeds. Two locations of the bruchids emergence hole in the seed in relation to the hilum were tested and they had no significant different effect on seed germination and seedling vigour. When seeds with a parasitoid emergence hole were compared with those with a bruchid emergence hole, there were no significant differences between them in seed germination ability and seedling vigour. The attack by bruchids caused a significant reduction in seed weight, between 0.03 and 0.08 g, depending on the genotypes/cultivars, corresponding to a decrease in nutrients available for the embryo development. In the 10 pea genotypes/cultivars compared there were no significant differences between them in seed germination ability and seedling vigour, whether seeds were attacked by bruchids or not.