Impact of Non-native Animals and Plants on Human Health

Abstract

Although many non-native species have human health impacts, especially as vectors of diseases, a minority are known to have venoms, poisons, and toxins of human significance, or to cause allergic reactions. Among animals, these effects are known in only a few taxonomic groups, where marine species are particularly well represented (e.g., jellyfish, mollusks, fish). A few venomous or toxic fish species cause acute burning pain, whereas systemic health symptoms are rare. Terrestrial animals that are famous for venomous bites and stings, such as scorpions and snakes, are relatively underrepresented as non-native species causing health problems. Insects such as bees, wasps, and ants are the most important group insofar as human health is concerned. Impacts usually include bites, stings, and certain injuries, but with jellyfish, skin contact alone is sufficient to produce severe dermatitis. In the case of animals possessing venom glands, a wide array of toxic compounds is injected, often with serious and even lethal consequences. A particularly dangerous situation results from mass attacks of bees, wasps, or ants in which multiple stings may be received. This behaviour is common in Africanized honeybees and accounts for their being the non-native species that has caused most human fatalities. Some non-native plant parts, especially fruits, are toxic if ingested. The sap of several plants can also be an irritant and cause dermatitis by contact, and in other cases spines and thorns can cause skin rashes. The major human health hazard posed by non-native plants is their allergenic pollen. The copious allergenic airborne pollen produced by some non-native ornamental tree plantings, even in areas where establishment has not occurred, highlights the fact that risks to human health for some non-native plant species do not require invasion.