One of the most persistent invasive plant species in New Hampshire is also widely regarded as one of the most beautiful. In fact, purple loosestrife has been called ?the beautiful killer.? ?Killer? because the purple flowering plant can completely take over a wetland, killing off all other species. In recent years, however, state biologists have begun to successfully fight back. Their weapon is a tiny brown beetle. N-H-P-R?s Doug Macpherson reports.
STATE ENTOMOLOGIST TOM DURKIS IS STANDING AT THE EDGE OF A WETLAND IN BEDFORD. ON A CLEAR SUMMER DAY WHEN THE PURPLE LOOSESTRIFE IS IN FULL BLOOM, IT?S EASY FOR EVEN DURKIS TO FIND SOMETHING TO LIKE ABOUT THE PLANT.
TAPE DURKIS 026 it does have some nice factors, it?s not all bad. Beekeepers like it. It serves as a good source of nectar during a period of time when other flowers aren?t available. it?s bad part is that sometimes you can see a field and it?s completely monocultured with purple loosestrife.
PURPLE LOOSESTRIFE IS NATIVE TO EUROPE. IT?S BELIEVED TO HAVE MADE ITS WAY TO NORTH AMERICA SOME 200-YEARS AGO. IT SEEDS MAY HAVE COME OVER ON A SHIP, ALTHOUGH NO ONE KNOWS FOR SURE.
THE PROBLEM IS, WHEN PURPLE LOOSESTRIFE ESCAPED ITS NATIVE EUROPEAN HOMELAND, IT ALSO ESCAPED ALL THE NATURAL PREDATORS THAT KEPT IT UNDER CONTROL. DOUG CYGAN, SENIOR ENVIRONMENTALIST FOR THE DEPARTMENT OF TRANSPORTATION, SAYS IN THE ABSENCE OF PREDATORS, IT?S INCREDIBLY PROLIFIC.
TAPE CYGAN 113 purple loosestrife populations have exponentially grown in magnitude. A single mature vigorous plant can produce over 2.5 million seeds, per year, some results indicate maybe 4.5 million seeds a year. So that?s quite a bit. The seed germinate pretty readily in sunlight. They can stay in submerged conditions for over two years.
PURPLE LOOSESTRIFE OFTEN TAKES OVER AN ENTIRE WETLAND ? CROWDING OUT NATIVE PLANTS, AND MANY OF THE NATIVE INSECTS, BIRDS, AND OTHER WILDLIFE. THAT?S BAD NEWS FOR CYGAN, BECAUSE WHENEVER THE DEPARTMENT OF TRANSPORTATION TAKES AWAY WETLANDS TO EXPAND ROADWAYS, IT MUST RESTORE OR EXPAND WETLANDS ELSEWHERE. IN FACT, THIS SITE IN BEDFORD USED TO BE A FILL DUMP FOR DEVELOPERS, UNTIL D-O-T RECLAIMED IT TO OFFSET THE EXPANSION OF THE INTERSECTION OF ROUTES 101 AND 114. BUT AS CYGAN POINTS OUT, IF NOTHING BUT PURPLE LOOSESTRIFE GROWS UP, THE EFFORT TO PROVIDE WILDLIFE HABITAT IS LARGELY WASTED.
TAPE CYGAN 162 We looked at chemical herbicide application but as you can see, we have residential areas surrounding this mitigation site, and the perceived notion is that chemicals are bad for the environment and it?s also a health risk. Which in many cases isn?t true, but we don?t want the perceived notion. So then we started looking at biological control.
IN 1996, NEW HAMPSHIRE BEGAN USING A TECHNIQUE THAT HAD WORKED WELL IN OTHER STATES. IT STARTED TO DEPLOY LEAF BEETLES. THE BUGS ARE LIGHT TAN IN COLOR, ABOUT THE SIZE OF A LADY BUG. LIKE PURPLE LOOSESTRIFE, THEY?RE NATIVE TO EUROPE. STATE ENTOMOLOGIST TOM DURKIS BUYS THEM FOR ABOUT 10-CENTS A BEETLE FROM A LABORATORY IN NEW JERSEY. IN A FIVE-FOOT HIGH STAND OF PURPLE LOOSESTRIFE, HE DEMONSTRATES THEIR RELEASE.
TAPE DURKIS 316 the beetles come in a biomailer. In this case we have over 600 /// they put in a little material just to keep it moist. And then we simply place them at the base of the plants ? they?ll find their way. This is a really dense site, so this is ideal in terms of having hosts plants readily available to them. /// 322 We leave them for 2-3 minutes now, and you?ll see they?ll quickly start dispersing. ///337 we can hold them for 24 hours after we receive them. ////338 you can see I?m being a little harsh on them right now trying to get the last few out. But their best chance of success is to at least get out of the container.
IT MAY SEEM A LITTLE RISKY ? INTRODUCING A NEW INVASIVE SPECIES TO CONTROL AN EXISTING ONE. BUT LEAF BEETLES ARE HOST SPECIFIC ? THEY EAT ONLY PURPLE LOOSESTRIFE. SO FAR, THE STATE HAS RELEASED ABOUT 90-THOUSAND BEETLES. AND, IT?S WORKING. AT ANOTHER WETLAND IN BEDFORD, CYGAN POINTS TO A SPOT WHERE HE RELEASED BEETLES LAST YEAR.
TAPE CYGAN134 it think we can make our way through here. Yeah, I think so, last couple of years this has been one of the more prominent plants for purple loosestrife out on this site. //// this plant was about five and a half feet tall. And as you can see, there are no remains of this plant evident coming through.
ALL THAT?S LEFT OF THE LOOSESTRIFE IS THE WOODY TISSUE OF THE STEMS. NEARBY, HOWEVER, ARE THICK STANDS OF JEWEL WEED, WATER PEPPER, AND CAT TAIL, AS WELL AS HABITAT FOR OTTER, MUSKRAT, AND ALL KINDS OF BIRDS. TOM DURKIS SAYS STATE OFFICIALS AREN?T TRYING TO ERADICATE PURPLE LOOSESTRIFE ? THEY RECOGNIZE THAT THE PLANT IS HERE TO STAY.
TAPE DURKIS 153 we?re trying to have a population of loosestrife beetles that remain in the site. So that eventually they will counteract ? if we lost all the purple loosestrife in the site we would loose the beetles as well, and we certainly don?t want to do that. We want to reach some type of equilibrium, where we have a certain number of beetles and a limited number of plants.
FOR N-H-P-R NEWS, I?M DOUG MACPHERSON.
