Beautiful but Deadly (Not really) H. Mantegazzianum produces a sap that can cause photodermititis in the area of contact. Furanocoumarins + Ultraviolet light from the Sun = photodermititis Blisters can be long standing and prone to leaving scars.
Enemy Release Hypothesis Presicts that top down regulation of the population will be lower in the range of introduction. When introduced into a new area, H. Mantegazzianum has the ability to outcompete native species. Obviously…. Wolfe (2002)- found that plants introduced into a new area were not susceptible to its native herbivourous predators. The lack of such a selection pressure would allow the plant to divert nrg and flourish in a non native area iff, other conditions were suitable. i.e. temperature, soil
Evolution of Increased Competitive Ability A plant invests a significant amount of energy into defense against herbivores in its indigenous environment. A newly introduced species will not have its usual host of herbivorous predators to weaken its fitness.. They lack – Monophagous – feeds within a plant genus (Heracleum) – Oligophagus – restricted to one family ( Apiaciae) – Polyphagous- feeding on different families. ( Memmot et al 2000)
Increased Interspecific Competition Interspecific competition is when two different species depend on a common factor, and then compete for it. The winner of such a factor is more fit for its environment. Because H. mategazzianum has fewer natural enemies in its unnatural environment it doesnt exert as much energy in defending against attack. This energy is focused elsewhere…..
Diverts Saved Energy to Growth Energy Since the plant has the ability to do so, it will use the supplemental energy in utilizing growth processes. Improved growth processes will help the plant use resources with a greater fitness, relative to other indigenous species.
Winter months contribute to competition H. Mantegazzianum dies back in the winter, further eroding the soil and making it even less unsuitable for other organisms to flourish.
Sources Eur. J. Entomol. 103:387-395, 2006:ISSN1210- 5759