Ragweed species (Ambrosia spp.) in Israel: distribution and allergenicity

Abstract

Ambrosia, specifically Ambrosia artemisiifolia, are known throughout the world as invasive, allergenic and noxious weeds. This research leads to the first map of the spread of Ambrosia species in Israel and describes the risk associated with their distribution to the public health. Six Ambrosia species were identified in Israel. There is one invasive species, A. confertiflora DC (Burr ragweed), which is most abundant in central Israel. There are three naturalized species: A. tenuifolia Spreng (Lacy ragweed) which is found in several locations; A. psilostachya DC (Cuman ragweed) and A. grayi (woolly leaf bur ragweed), which are restricted to a single location each. There are two casual species: A. artemisiifolia L. (short ragweed, common ragweed) and A. trifida L. (Giant ragweed). There are pronounced and clear differences between the species in their life cycle, morphology and phenology, which may explain the level of invasion of each one in Israel. The causes of the invasion are mainly anthropogenic. Many populations of Ambrosia are found near fishponds and animal feed centers, indicating that ragweed seeds feasibly arrived to Israel in grain shipments. Human sensitization to local pollen extracts of A. confertiflora and A. tenuifolia was studied by skin test reaction and compared with commercial extracts of A. artemisiifolia and A. trifida. Patient’s response was three times stronger in A. confertiflora with respect to the other three species. The rapid dissemination of A. confertiflora, the manner in which its pollen is dispersed and its allergenic potential indicate risks to public health.