The origin and worldwide distribution of regweed- a review

The aim of the study is to provide a survey on the history of ragweed worldwide. Its climate dependence, impacts in agriculture, health effects and social costs are also presented. In Europe common ragweed (Ambrosia artemisiifolia) is predominant of all Ambrosia species that is supported by population genetic data. The most important habitat areas of ragweed and the highest pollen concentrations occur, in decreasing order of the pollen levels (1) in the south-western part of the European Russia, (2) in the southern and eastern parts of Ukraine, (3) in the Pannonian Plain in Central Europe, (4) in the Rhône-Alpes region in France, furthermore (5) in the Po River valley in Italy. Besides Europe, ragweed occurs in China, India, Japan and in other Asian countries, furthermore in Australia and the Unites States of America. However, beyond the USA little information is available. Warming trends due to the climate change favours the expansion of ragweed, producing higher pollen levels worldwide. In association with the warming, increasing ambient CO2 levels generate greater biomass and increased pollen production. Hence, ragweed pollen production can be expected to increase significantly under predicted future climate conditions, bringing severe impacts to areas that have yet been suffering slightly