Webworm is New
Webworms are having a field day in New Zealand.
Brian Patrick reported in 2004 that "surveys convinced
authorities that the species had entered New Zealand through
the port [Port Chalmers] and had been
resident in New Zealand for at least one summer prior to the
2003-2004 summer". So numerous were
webworms that year that "complete destruction of individual
plants above ground" was commonly seen.
Although wild parsnips had made their
way to New Zealand over a 150 years earlier (brought along by colonists
for its delectable culinary properties, of course), the appearance of
its arch nemesis must be quite a shock, and indeed it is! Never in our
25 years of experience in America or Europe have we seen such
devastation as is being meted out by the webworms in New Zealand.
In some of the populations at the center of the distribution, we found
close to 3/4 of the plants entirely stripped of flowers and seeds.
Stems of these plants were chock full of webworm pupae. Moreover,
as soon to be reported in the Proceedings of the National Academy of
press release), webworms are substantially altering the selection pressures on
plant chemistry, and not just furanocoumarins. In
fact, we suspect that a massive reshuffling of chemical characters,
including furanocoumarins, terpenes, fatty acid esters and others, will
result and will be occur rather quickly. How fast is
anyone's guess, but with a short generation time and a limited seed
bank, probably not long--recall that parsnips appear to have responded
to webworms within 20 years of reassociation in