Tuesday, September 20, 2016

Fighting unwanted insects -- with more insects

            When Jean Williams discovered a blood-red beetle with long black antennae consuming the lilies in her Wakefield garden a decade ago, she recognized it at once as an invasive insect she had just learned about in a gardening class. University of Rhode Island researchers had been on the lookout for the new invader, which until then had not been found in South County. So she called URI entomologist Richard Casagrande, who verified that the insect was a lily leaf beetle, a Eurasian species responsible for wiping out populations of native and ornamental lilies in much of the Northeast.
            Today, the beetle is not nearly the pest it was back then. That’s because Casagrande and colleague Lisa Tewksbury identified the beetle’s natural enemy in Europe, a tiny parasitic wasp, and have been raising and releasing small numbers of them wherever lily leaf beetles have been found in the region. The wasps lay their eggs exclusively in the larvae of lily leaf beetles, and when the eggs hatch, the wasp larvae kill and consume the beetle larvae from the inside.
            “The wasps are such teeny weeny little iridescent things that I had no fear of them at all,” says Williams of the insects released in her garden. “By the following year, they were definitely starting to control the beetles, and within a few years the beetles were mostly under control.”
            Casagrande calls the parasitic wasp “fabulously successful” at controlling the lily leaf beetle. He and Tewksbury have released the wasps in numerous locations in Rhode Island and Massachusetts, and they have shipped them to New Hampshire, Maine, Connecticut and Ontario for release by partner researchers in those locations. Everywhere the wasps have been released, the lily leaf beetle population crashes within a few years, making the wasp an ideal poster child for what is known as biological control.
            The invasion of non-native species like the lily leaf beetle is a growing problem that has significant implications for native biodiversity, human health and the economy. Once an invasive species becomes established, it is a costly and challenging undertaking to get rid of it using chemical pesticides, mechanical means and other strategies. Despite the research required to do it safely, biologicalcontrol – what the U.S. Fish and Wildlife Service calls the purposeful use of an invasive species’ natural enemies to reduce populations – is often the most successful strategy for eradicating invasives....

Read the complete story in the September 2016 issue of Rhode Island Monthly.

Saturday, September 17, 2016

Rhode Island airports are last refuge for some grassland birds

Early results from the first year of an effort to document the status of breeding birds in Rhode Island have shown what many birdwatchers expected – some species have disappeared from the state since a similar survey was conducted in the 1980s, while others have moved into the area for the first time.
            But perhaps the most interesting result of the Rhode Island Breeding Bird Atlas so far is that two bird species that nest in grassland habitat have been observed breeding in good numbers at many of the airports around the state – but nowhere else yet.
            According to Charles Clarkson, who is coordinating the five-year project, horned larks and eastern meadowlarks were documented breeding at the airports in Warwick, Quonset, Lincoln and Westerly.
            “These birds do very well in short grassland habitat that isn’t necessarily mowed regularly, but where the grass doesn’t grow very tall,” he explained. “They used to be more generally distributed in open areas and natural grasslands, but now these birds are restricted to these very isolated tiny pockets of managed habitat intended for airplane use.
            “It’s a testament to how well-managed these airports are,” Clarkson added. “They’re not consciously managing the properties for these species – it’s probably the opposite of what they want – but the airports are the strongholds for these species in the state.”
            Two other uncommon bird species have also found airports to their liking. American kestrels, small falcons that hunt for food over grassland habitat, were found nesting at several of the airports and in only a few other sites in Rhode Island. Savannah sparrows breed in large numbers at the airports but much less commonly in other places.
            Clarkson said that dwindling grassland habitat around the country has been a serious concern to conservationists for many years. Due to habitat loss, grassland-nesting birds are declining at a greater rate than those that prefer other habitats.
            “What’s happening here in Rhode Island is a snapshot of what’s going on nationwide,” he said. “All throughout the Midwest and prairie states and elsewhere, you’ve got shrinking grassland habitat and the conversion of the habitat to large-scale corporate farms. Rhode Island is emblematic of a bigger problem.”
            Due to airport security, documenting the breeding success of birds at the Rhode Island airports was quite a challenge. As part of the Breeding Bird Atlas, Clarkson identified 8,250 random places in the state for what he called “point counts” – sites where participants look and listen for birds for a specified time. About 30 of those random sites turned out to be on properties managed by the Rhode Island Airport Corp.
            “Some were even right in the middle of the runways, so I wasn’t sure we were going to be able to survey those sites,” he said. “I had to go through a number of channels to get the proper permits and airport passes.”
            He is grateful to Paul Poirier, who is in charge of safety training at the airports, who helped him through the process of securing approvals and escorted him to the various airport sites to conduct his bird counts.
            “Paul was able to get me everywhere, even on the taxiway,” Clarkson said. “I was standing in the middle of a taxiway counting birds at six in the morning and not concerned about getting run over by a plane in the process, thanks to Paul.”
            In total, Clarkson documented about 15 pairs of breeding meadowlarks at the state’s airports and about 25 pairs of horned larks. He also observed a large number of young meadowlarks and horned larks after they left their nests.
            “I expected the birds to be there, but I didn’t expect to see so many,” he said. “I was pleasantly surprised.”
            Clarkson called the habitat at airports a “double-edged sword” for grassland-nesting birds in Rhode Island.
            “The birds have this habitat that is likely going to be around for quite some time, affording them the habitat they need to continue breeding,” he said. “But you’ll never see the population here expand, because these are dead-end populations. The airports are a habitat hold-out for these birds, but there’s not much hope that they’ll ever flourish in Rhode Island again.”
            Other notable results from the first year of the Rhode Island Breeding Bird Atlas include the disappearance of northern bobwhite, a formerly common member of the grouse family that requires large areas of grassland habitat, and no records of breeding by magnolia warblers or cerulean warblers, which previously were found at several sites. On the plus side, atlas volunteers documented breeding by common ravens in a number of communities, a species that was not found in the state during the first atlas, as well as the rare saw whet owl and northern goshawk.

This article first appeared on EcoRI.org on September 17, 2016.

Friday, September 16, 2016

Will fall foliage be a washout?

            It’s almost time to start paying attention to the emerging signs that our foliage is about to burst into its fall colors – what one friend refers to as “the hunt for red October.” But this year brings with it great uncertainty. 
The massive defoliation throughout the region by winter moth and gypsy moth caterpillars put great stresses on our trees, as has the considerable drought we have experienced. Both of these factors have made the always difficult job of predicting the timing and brilliance of the fall foliage display even more difficult.
            Local experts tell me that their best guess is that we may experience a slightly muted display this year, and the caterpillars are mostly to blame.

The trees that were defoliated in May and June – mostly in western and southern Rhode Island, and to a lesser degree in the East Bay – produced what botanist Keith Killingbeck calls “a second flush of leaves” in July. Most deciduous plants can do this if the first batch of leaves becomes defoliated early in the season.
But from what Killingbeck has observed, the new leaves appear to be much smaller in size than the mature leaves that were consumed by the caterpillars. And there may even be fewer leaves per tree compared to normal years. This means there is less surface area to magnify the colors. So even if the individual leaves are as beautiful as ever, the trees may not look as stunning.
Killingbeck, a retired professor at the University of Rhode Island, also worries that the process of producing that second flush of leaves required so much energy that the trees may be too exhausted to complete the metabolic processes that produce the colors. In a typical year, the trees suck nutrients stored in the leaves back into the branches and root system before the leaves fall. That, in a nutshell, is what causes the leaves to turn colors. But the trees may not have the energy to go through that process, meaning the leaves may still be partly green when they drop from the trees.
On the other hand, many oak trees appear to have aborted the process of producing acorns this year, which may be a strategy to conserve energy so they can experience a normal fall foliage season.
And if that’s not enough, the severe drought that much of the region experienced might disrupt our fall colors, too.
“What normally happens in drought years is that the leaves are lost earlier than normal, and sometimes if there’s been a severe drought, they turn brown and drop rather than turning brilliant yellow or red,” explained Killingbeck.
The effect of the drought could be reversed, however, if we get a good dose of rain in the weeks leading up to the change of colors. If we do, then the timing of the change and the brilliance of the colors may be unaffected.
Too much rain at the wrong time, though, could also quash the fall colors. Heavy rains during the peak of the foliage season could leach out the compounds that provide the color through tiny fissures in the leaves.
All of which explains why it’s so difficult to predict what to expect from our fall foliage. There are just too many competing factors to take into consideration. So instead of worrying that this year’s colors will be a disappointment, I’m just going to appreciate whatever we get and know that we’ve got another shot at a spectacular display next year.

This article first appeared in the Independent on September 15, 2016.

Wednesday, September 14, 2016

Tobacco hornworms: Big, green and in the garden

            The big, meaty green caterpillars that many of us have been fighting to eradicate from our tomato, eggplant and pepper plants this summer make plenty of people squirm. In part it’s because they are among the largest caterpillars in the region, sometimes reaching close to three inches in length, with reddish horns that look like stingers (but aren’t). We also hate them for their voracious appetites and preference for consuming our favorite crops.
            But before you pick and squish every tobacco hornworm caterpillar you see, think about the beautiful giant moth they become and the important role they play as native insects in the environment. If you listen to Sam Jaffe, proprietor of The Catepillar Lab in Keene, N.H., you may reconsider plucking them from your plants at all and instead try to protect them.
            Once they complete their metamorphosis, tobacco hornworms become Carolina sphinx moths, large-bodied moths with a five-inch, coffee-colored wingspan that enables them to hover over flowers like hummingbirds. Jaffe says they have the longest tongues of any insect in New England, allowing them to feed on and pollinate deeper flowers than any other moth.
“They’re very impressive and long-lived, and they almost give off the impression of being mammal-like – fluffy and hairy with large eyes that reflect red in the light,” said Jaffe. “They’re special in a lot of ways.”
            And not just as adult moths. The caterpillars exhibit some pretty special behaviors, too. After hatching from tiny eggs on the underside of leaves, the green caterpillars decorated with diagonal white lines go through five stages of growth, called instars, growing larger with each stage.
By the time they reach their fifth instar, they can become quite bold, occasionally rearing up on their hind legs when disturbed and thrashing their head back and forth. Jaffe calls that behavior regal, though he admits that he would have trouble convincing tomato farmers of that.
He would have even more trouble if he pointed out that tobacco hornworms may even try to nip your finger if you let them, though their mandibles aren’t strong enough to break your skin. Those mandibles also produce an audible clicking sound that is believed to serve as a warning to predators.
            When the caterpillars have matured and finished feeding, they drop to the ground and dig an underground chamber in which to pupate, remaining there through the winter months until the moth emerges in the spring.
            From an ecological perspective, tobacco hornworms play numerous roles. The early stages of the caterpillar, when they’re still tiny, serve as food for a wide variety of birds, and larger birds and scavenging mammals will eat the mature caterpillars, too.  Other insects eat them as well, like stinkbugs and assassin bugs, which insert their uniquely-adapted mouthparts into the caterpillar and suck it dry.           
            And then there are the parasitic wasps. One variety injects its eggs inside the egg of the hornworm, and when the eggs hatch, the wasp larvae kill the hornworm egg and emerge as adult wasps. Another version lays its eggs in the caterpillar, and when the wasp larvae emerge, they spin cocoons on top of the caterpillar. So if you see a hornworm covered in tiny white cocoons, that’s a hornworm you shouldn’t kill, because all those cocoons will become more wasps that will kill more hornworms. It’s a natural process that keeps the caterpillar population under control. 
            If you still can’t make yourself love tobacco hornworms, put one in a jar and watch it for a few weeks. Jaffe calls them “great guest caterpillars” that are fun to observe and easy to rear. He says farm camps and schools with gardens can easily incorporate them into educational programs.
            Just don’t’ confuse them with the very similar tomato hornworm, which has a straight blue horn rather than the curved red horn of the tobacco hornworm. Tomato hornworms have mostly disappeared from the Northeast, so almost any hornworm you see will likely be the tobacco variety.
            While you can’t be faulted for removing hornworms from your crops, Jaffe hopes you will try viewing them through his eyes. If you do, you’ll see an important part of our natural heritage, one that is helping him demonstrate that caterpillars are fascinating insects that can be used to inspire the next generation to appreciate all that is wild.

This article first appeared in the Bennington Banner on September 9, 2016.

Wednesday, September 7, 2016

Diamondback terrapins making a stand in Rhode Island

            One of Rhode Island’s rarest turtles, the diamondback terrapin, has been discovered in new locations in recent years, and those monitoring the animals say the species is holding its own in the state and may even be increasing in number.
The only turtle in the state adapted for life in salt marshes, coves and other quiet brackish waters, diamondback terrapins have been closely watched for at least 27 years at their major stronghold in Barrington’s Hundred Acre Cove. That’s how long Charlotte Sornborger has been monitoring their nesting success there.
Every year in late May and June, she and a team of volunteers watch as the female terrapins emerge from the water to lay their eggs in farm fields and other sites with sandy soils adjacent to the cove. She estimates that about 550 terrapins breed in the area.
“The population seems to be sustaining itself,” she said. “They could be growing, too, though maybe we’re just getting better at counting them.”
It takes about 65 to 70 days for terrapin eggs to hatch, with the last ones this year emerging from their nests on Labor Day weekend.
Coyotes, skunks and raccoons used to scavenge the eggs in many of the nests, destroying between 200 and 300 nests each year. But that was before Sornborger began protecting the nests with wire mesh “excluders,” which prohibit mammalian scavengers from digging down to reach the eggs six inches below the surface.
Sornborger said that “a decent population” of diamondback terrapins is also found in the mouth of the nearby Palmer River, but she has been unable to learn exactly where they nest, so no one knows how many are found there.
Small numbers of terrapins have recently been discovered in the vicinity of Smith’s Cove, Jacob’s Point and Colt State Park, all in the Bristol and Warren area.
“We don’t know where they nest at any of those locations either,” she said. “It’s possible the Hundred Acre Cove population is on the move, so they may have come from there.” But, she said, the terrapins may have always been at those locations and no one has ever noticed them before.
That’s likely the case in Westerly, too, where a few terrapins have been found at Napatree Point in recent years.
"We found a dead terrapin at the end of June, but nothing since," said Janice Sassi, director of the Watch Hill Conservancy. "There were indications the past two years that they are nesting."
A determined effort by the Rhode Island Natural History Survey in 2013 also found about 15 terrapins in some of the coastal salt ponds in South County.
The biggest surprise, however, was the recent discovery of a significant population of diamondback terrapins nesting at a private beach at Rocky Hill School at the mouth of the Hunt River in Warwick.
Laura Meyerson, associate professor of natural resources science at the University of Rhode Island, was shown a video of a terrapin hatchling on the beach two years ago and learned that a teacher at the school has known about the population for several years.
“We think they’ve been there for a while,” she said. “It’s a quiet protected beach on the Rocky Hill property, so there aren’t a lot of people there to notice them or disturb them.”
Meyerson received a grant from the National Science Foundation to monitor the Rocky Hill terrapins with Rochelle Devault, a science teacher at the school. Along with students from URI and Rocky Hill, they were pleased to observe 87 nests this summer, but unfortunately all but three were eaten by foxes, raccoons, skunks and domestic dogs.
“It’s not a good situation,” Meyerson said. “We didn’t observe any hatchlings at all, though the terrapins hide their nests well – they’re masters of camouflage – so it’s possible we missed some.”
Devault thinks there may be many more terrapins than the 87 they observed.
“Our population is extremely shy,” she said. “The number of live terrapins I’ve seen in the water is pretty high, but the number that come on land to nest is far reduced from those I see in the water. They look up at me and turn around and head back in the water.”
As a result, the terrapin monitors at Rocky Hill now hide behind nearby vegetation as they keep track of the nesting turtles.
Meyerson and Devault plan to explore other marshes near Rocky Hill next year to look for additional terrapin nesting locations. And they will install signage to direct dog-walkers away from the nesting area. They also hope to learn from Sornborger how to better use excluders to protect the nests.
“We definitely have to figure out how to do a better job at limiting predation,” Meyerson said. “We really want to build some momentum at the school to protect the terrapins.”

This article first appeared on EcoRI.org on September 7, 2016.