Bruchid seed infestation and development time in three host species of Acacia

Abstract

Recruitment of Acacia trees in the Negev desert and the Arava valley (Syrian-African Rift) of Israel is highly negatively affected by bruchid beetles. The effects of three Acacia tree host species were examined on the life histories of four bruchid beetle species that commonly occur in the Negev. There was extreme variance in the development time of these beetles, ranging from one month to one year. Additionally, mean values of Acacia seed infestation by bruchids were about 13% of seeds in the laboratory, where newly-hatched bruchids were removed from the population, yet values as high as 97% of seeds were infested in the field, which is due to re-infestation of seeds by newly-hatched bruchids. There were highly significant differences in the presence/absence of bruchid beetles across Acacia species. A. raddiana and A. tortilis occurred in the same habitats yet differed in the numbers of bruchid individuals of each species. The four bruchid species infest all three Acacia species but their effects are markedly different. Most prominent are the presence/absence of bruchid species in certain host tree species.