Parthenium weed and annual ragweed are closely related members of the Asteraceae, known for their high allergenicity. The detrimental effects on human health of the more temperate annual ragweed are very well known. However, those of the more tropical parthenium weed are less well known and in fact much more severe, affecting many tens of millions of people each year.
In eastern North America a species of weed has become an aggressive invader. Garlic mustard (Alliaria petiolata) is one of the most rapidly increasing woodland invasive plant species, spreading across northeastern and midwestern USA and southeastern Canada ata rate of nearly 2,500 square miles per year.
The plant was most likely introduced to North America in the 19th century, taken from its native habitat of Eurasia by settlers for medicinal and culinary use. Although the crushed leaves and seeds of garlic mustard smell like cultivated garlic and have been used as flavouring in cooking for centuries, the plant actually belongs to the cabbage family.
Whether trying to cajole one out of your office or running for cover after it seems a little too interested in your food we have likely all encountered the common wasp (Vespula vulgaris) more than once during this particularly wasp-heavy summer. But did you know that this is just one of 9000 species of wasp found in the UK and without a microscope you’re unlikely to ever see the vast majority of them. You might also not know that they provide us with great ecological services including pollination of both our crops and wildflowers as well as controlling insect populations which spread human and agricultural diseases.
By Giuseppe Mazza and Elena Tricarico, Università degli Studi di Firenze, Italy
Invasive species are becoming a popular topic in newspapers: when articles appear, they mainly report the damages invasive species can cause to our ecosystems (e.g. reduction or disappearance of native species as well as habitat modification) or to our economic activities: fishing or boating can be halted by mats of the South American water hyacinth, several insects can affect our agricultural production or new diseases can be transmitted to reared species. However, these species can also heavily affect human health and wellbeing.
The damage that invasive species can cause to the environment and the economy are well known, but impacts on human health have been much less analysed. However, invasive species can cause impacts ranging from psychological effects, phobias, discomfort and nuisance to allergies, poisoning, bites, disease and even death. Invasives experts Giuseppe Mazza and Elena Tricarico of the University of Florence, Italy say that in addition to these direct effects, some work in more indirect ways. Humans are menaced by alien invasive species affecting the services provided by ecosystems. “These services are vital to our well-being: changes may decrease the availability of drinking water and of products from fisheries, agriculture and forestry, alter pollination and impoverish culture and recreation,” say Mazza and Tricarico.
Around 30-40% of crops around the world are lost to insect pests thereby affecting the ability of the 500 million small-scale farmers around the world to contribute towards the goal of achieiving zero hunger and ending poverty. Reducing losses by just 1% could feed millions more people but many countries in the Developing World need support to implement biological control programmes to reduce food losses.
As part of CABI’s mission to help farmers grow more and lose less, we have been funded by USAID – via the United States Department of Agriculture (USDA) – to help Pakistan improve its sanitary and phytosanitary (SPS) systems and therefore open up its fruit and vegetables to more high-end global markets that were previously untapped. Currently these products only contribute 13% of the country’s export but improvements to its SPS capabilities could see this number rise significantly.
Over the last few years, biological invasions have become a regular topic in the news. Today the general public is probably better informed about the negative environmental and economic impacts alien invasive species can cause than ever before. However, concern about invasive species and the search for methods to sustainably manage them has a much longer history, dating back to the 19th century.