Thursday, May 25, 2017

Too late, baby, now it's too late

            When Rhode Island House Minority Leader Patricia Morgan sent a letter to Governor Gina Raimondo on May 2 asking that a plan be developed and launched to eradicate gypsy moth caterpillars throughout the state, she was likely responding to the highly-visible emergence of masses of tiny caterpillars from their eggs that week. Her reaction could be considered understandable, since just walking outside in proximity to trees left many residents with specks of moth larva clinging to their clothing.
            According to one expert, however, a statewide eradication program is unnecessary and may even backfire. And by the time the caterpillars hatch, it’s already too late to plan and
implement an eradication program.
            Heather Faubert, an entomologist who directs the Plant Protection Clinic at the University of Rhode Island, agrees that the state is in for another year of forest defoliation that will likely be similar to the 230,000 acres that were defoliated by gypsy moth, winter moth and forest tent caterpillars in 2016.
            “But by the end of this growing season, the population of gypsy moth caterpillars will crash and they won’t be a problem next year,” said Faubert, who monitors caterpillar populations for the state’s fruit growers. “The diseases that usually control the population start spreading when the population is high and when we have wet weather in May. We’re having a wet May, so I expect the population to crash all on its own this year.
            “But not before the gypsy moths that are already here do quite a bit of damage,” she added.
            She said that the only way to eradicate gypsy moths throughout the state would be through aerial spraying of an insecticide.
            “There’s no other solution,” Faubert said. “And it would need to be done by the third or fourth week of May. Logistically it’s not even possible to organize a spraying program that quickly.”
            She said that the usual insecticide used to kill gypsy moth caterpillars in aerial spraying is not available commercially and must be ordered by state governments in the autumn. The next best choice is one of the so-called Bt insecticides, which attack all caterpillars, not just gypsy moths, wiping out all moth and butterfly populations in the area sprayed.
            “There was opposition to aerial spraying in the early 1980s, and there would be a lot more opposition now,” said Faubert.
            Even if a plan were developed, the insecticide acquired, opposition quelled, and spraying took place during the most optimal time, Faubert believes it would likely prolong the gypsy moth outbreak.
            “If we spray, there will certainly be lots of pockets of places that don’t get sprayed,” she said. “And the chemicals are never 100 percent effective. So if, say, 15 percent of the caterpillars in the state survive, the caterpillar population won’t be dense enough to spread the diseases that usually kill them off, so we’ll be facing the same problem next year.”
          Unfortunately, while the prognosis for next year is good, the state is in for a rough summer this year. Even if May remains wet and the diseases spread throughout the caterpillar population as Faubert predicts, the caterpillars won’t die until they are full grown and have already eaten a huge number of leaves.
Sadly, it’s not just the trees that will be affected.
            A number of local ecologists have noted that forest defoliation allows more direct sunlight onto the usually shaded forest floor, which means sun-loving invasive plants have a greater opportunity to spread through the forest; shade-loving frogs and salamanders may struggle to remain cool and moist; and some birds and small mammals may find it more difficult to hide from predators.
            The increased sunlight through the trees also means that the water temperature in many forested streams and ponds will likely increase, resulting in a reduction in dissolved oxygen levels in the water that can cause distress in sensitive aquatic species.
            On the other hand, URI ornithologist Peter Paton said that several species of migratory songbirds that feast on gypsy moth caterpillars, especially black-billed and yellow-billed cuckoos, will likely benefit from the abundance of caterpillars in the forest this year. Birdwatchers in the area noticed an unusually large number of cuckoos last year, and this year’s population should be even greater. Indigo buntings, which prefer open habitat, also tend to experience short-term increases when trees are defoliated.
            David Gregg, director of the Rhode Island Natural History Survey, said that he found unusually healthy populations of some spring wildflowers in Snake Den State Park in Johnston this month, which he attributes to the defoliation from last year’s gypsy moth outbreak.
            “Most forest floor plants are adapted for growing in the dark of the forest canopy, but some are still capable of growing faster and better if they have more light,” he explained. “So when there's defoliation, they have a good year. That means they put away a lot of food into their roots and have a good next spring.
            “But,” he added, “most of the rest of the gypsy moth news is bad.”

This article first appeared in Newport Mercury on May 23, 2017.

Wednesday, May 24, 2017

Mowing less does more good

            Farmers, gardeners and others whose livelihoods depend on a healthy population of wild bees to pollinate cultivated crops and other plants have become increasingly worried in recent years. The global decline of bees – due to pesticides, climate change and natural parasites and pathogens – has led to reports that the world food supply may be threatened, along with millions of jobs and an unknown number of ecosystems.
            As worrisome as it is, there appears to be little that most of us living regular lives in suburbia can do to improve the situation. Yes, we can plant native pollinator gardens to provide
nectar to bees and butterflies in our yards. And if you haven’t already done so, then I encourage you to take that step. But not everyone has room for a garden or the time and money and physical ability to plant and maintain one.
            But recent research by an urban ecologist in Massachusetts suggests that there is an even easier step we all can take to benefit local bees. And rather than requiring that we do something more, it instead requires that we do less than most of us already do.
            Susannah Lerman at the U.S. Forest Service’s Northern Research Station in Amherst sought to determine whether lawns could somehow provide useful habitat for bees. So she spent two years regularly visiting 16 suburban lawns in Springfield, Mass., some of which were mowed weekly and others every other week or every third week.
What she found was quite surprising.
            During her visits to the lawns – none of which were treated with pesticides or herbicides – she discovered 64 flowering plant species growing among the blades of grass, including dandelions and clovers, of course, but also violets, smartweed, cinquefoil, rockcress and others considered by everyone to be wildflowers. These “spontaneous flowers,” as she called them, were not intentionally planted, but they still provided an abundance of pollen and nectar to bees.
            What was even more surprising is that Lerman and a colleague collected and identified 111 different kinds of bees on the properties. That’s about one quarter of the total number of bee species ever found in Massachusetts. One yard had an amazing 53 species. And even more astonishing than that – the most abundant species of bee was a sweat bee that had not been recorded in the state since the 1920s.
            So how can we do less to help our local bees? By mowing our lawns less often, Lerman said. It turns out that the lawns with the largest number of bees on them were the lawns mowed every two weeks instead of every week. That extra week in between mowing allowed some of the slower-growing spontaneous flowers the time they needed to bloom and provide nectar to the bees.
            Lerman concluded that the best thing most homeowners can do to reverse the decline in bees is to forego the use of chemical lawn treatments, plant a pollinator garden if possible, and only mow the lawn every other week at most.
            Some of the lawn-obsessed among us may find it challenging to follow these suggestions because they see dandelions and clovers as weeds. But Lerman told me that “we need to change their perceptions and show that those plants are really providing wildlife habitat.”
            So do a little less to your lawn this year, and feel good that you’re actually doing a little more for your local bees at the same time.

This article first appeared in the Independent on May 22, 2017.

Saturday, May 20, 2017

Documenting Rhode Island's ant diversity

            James Waters calls ants “the most ecologically dominant animal on Earth,” which may sound like an exaggeration from an enthusiastic ant aficionado. But the assistant professor of biology at Providence College can back it up.
Ants have colonized nearly everywhere around the globe except Antarctica; more than 12,500 species are recognized; and they are social creatures that have a division of labor, communication between individuals, and the ability to solve complex problems. There are so many ants, in fact, that their total biomass surpasses the biomass of every human in the world.
            And yet very little is known about the ants that call Rhode Island home.
            That’s where Waters comes in. At a lecture on May 11 sponsored by the Rhode Island Natural History Survey, he outlined his efforts to characterize the biodiversity and natural history ofthe ants living on the PC campus, as well as a broader effort to do so for the entire state.
            Waters said he is following in the footsteps of Rev. Charles Reichart, a PC professor for 50
years who died in 1997 and whose collection of thousands of insects now resides at the Smithsonian Museum of Natural History.
            “Three years ago my students started taking photos of the local ants on campus, and now we’re taking a more scientific approach to figuring out what ants live there,” said Waters, who joined the PC faculty in 2014. “We set up a grid on campus, set up three pitfall traps per grid with soapy water in them, and collected any ant that fell in.”
            It turned out that counting and identifying all of the collected specimens was a laborious task. In 10 weeks, Waters and his students amassed more than 2,000 specimens, and it took almost two years of work to sort and identify them. They found 16 species of ants on the college campus, although since they only placed their traps on the ground, they probably missed many other species that live in trees and other habitats.
            The most common ants the students collected were pavement ants, carpenter ants, labor day ants, and the bizarrely named somewhat silky ants and yellow-legged crazy ants. Among the rarest species documented were the short-horned slender ant, long-spined acorn ant, tawny seed-harvesting ant, pale ant and Asian needle ant.
            The discovery of the Asian needle ant was particularly unexpected, since it had never before been recorded in New England. An invasive species, it arrived in the United States in the 1930s and has become common in the mid-Atlantic states, but the closest it was believed to have come to Rhode Island was New York.
            “So I told all my students that if they found another one on campus they wouldn’t have to take the final exam,” Waters said. “Most of them found one, almost all around one building on campus. I have no idea why they were at that one building, but they haven’t been found anywhere else on campus, or in Rhode Island or New England.”
            Among the other species found on the Providence College campus by Waters’ students was the common vampire ant, a species so small that it can barely be seen with the naked eye. “They don’t drink our blood,” Waters said, “but they do puncture their own babies and drink the hemolymph,” a blood-like fluid in invertebrates.
            Also found were five species of acorn ants -- tiny insects that live inside acorns – and many citronella ants, which smell like citronella oil.
            According to Waters, most ants produce a distinctive odor from trace amounts of a natural oil they put on their exoskeleton. Some ants can even distinguish what colony an individual ant is from based on its odor. And he said that some ant experts at Harvard University are adept at identifying ant species by their odor alone.
            Waters can’t do that yet, but he’s learning. He became interested in ants while in graduate school at Arizona State University, where he modeled the flow of air through insect lungs as part of a study of insect metabolism. Other students were studying social insects, including ants.
            “I asked them about the energy use of an ant colony, and no one knew the answer,” he said. “I only got interested in the natural history aspect of ants after grad school. I had all this data on the energy use of these species, but I didn’t know what they did on a daily basis. I wound up in Rhode Island and didn’t know anything about the ants here. Now I’m just trying to discover what I can about our local species.”
            Over the next two years, he plans to develop and conduct a systematic survey of ants throughout the state. As a relative newcomer to Rhode Island, he is still trying to identify interesting places with unusual habitat to survey. He also intends to visit the Smithsonian to review Reichart’s insect collection to see what ant species the former PC professor found in the mid-1900s.
            “So far, we’ve identified lots of new state and county records,” Waters said, noting that he estimates that about 100 ant species live in Rhode Island. “But we still have a long way to go.”

This article was first published in on May 18, 2017.

Friday, May 12, 2017

A secret sensor

            Anyone who has paid even a little attention to plants and trees in late winter and early spring know how responsive they are to temperature. In years when the winters are warm, many trees and flowers bud early. But until now, the molecular mechanism that allows them to detect temperature has been unknown.
            A team of scientists from the University of Cambridge in England has revealed what they call the “thermometer molecule” that enables plants to develop according to seasonal temperature changes. During the day, the plants use the molecules, called phytochromes, to detect light, but they change their function in darkness to become a cellular temperature gauge to measure heat at night.
            Their research was published last fall in the journal Science.
            According to lead researcher Philip Wigge, who compares phytochromes to mercury in a thermometer, the pace at which the molecules change is directly proportional to temperature – the warmer the temperature, the faster the molecules change to stimulate plant growth.
            Sunlight activates the molecules during the day, binding themselves to DNA to slow plant growth. The phytochromes are rapidly inactivated when plants become shaded, enabling them to grow faster to find sunlight again. Wigge said this is how plants compete to escape each other’s shade. Light driven changes to phytochrome activity can occur in less than a second.
            But at night, the molecules gradually become inactive in a process called dark reversion. “Just as mercury rises in a thermometer, the rate at which phytochromes revert to their inactive state during the night is a direct measure of temperature,” Wigge said. “The lower the temperature, the slower phytochromes revert to inactivity, so the molecules spend more time in their active, growth-suppressing state. This is why plants are slower to grow in winter.”
“Warm temperatures accelerate dark reversion,” he added, “so that phytochromes rapidly reach an inactive state and detach themselves from DNA, allowing genes to be expressed and plant growth to resume.”
Not every plant species relies equally on their phytochromes, however. Some, like ash trees, rely more on measuring day length to determine their seasonal timing, whereas oaks rely primarily on temperature, meaning they use their phytochromes to dictate their development.
            The research was conducted on a mustard plant, but the scientists say the phytochrome genes are found in crop plants as well.  In fact, Wigge said, in light of the increasingly unpredictable weather and temperatures due to climate change, the discovery could help in the breeding of more resilient crops.
            “It is estimated that agricultural yields will need to double by 2050, but climate change is a major threat to such targets,” he said. “Key crops such as wheat and rice are sensitive to high temperatures. Thermal stress reduces crop yields by around 10 percent for every one degree increase in temperature. Discovering the molecules that allow plants to sense temperature has the potential to accelerate the breeding of crops resilient to thermal stress and climate change.”

This article first appeared in Northern Woodlands magazine on May 10, 2017.

Changes in ranges

            Researchers have long believed that the changing climate will force most species of birds to shift their range to follow their preferred climate niche. Rather than adapting to the new climate conditions in their current range, birds will in most cases move north or higher in elevation as the planet warms.
            But a new study by a former University of Massachusetts ecologist overturns that long-held assumption. Joel Ralston, now at St. Mary’s College in Indiana, found that a previously ignored factor also plays a role in determining how and if birds will shift their range – population trend.
            Ralston discovered that birds that have increased in abundance over the last 30 years now occupy a wider range of climate conditions than they did 30 years ago, and declining species are occupying a smaller range of climate conditions than 30 years ago.
            “It was previously thought that as species expand their ranges, they would do so while maintaining their climate niche,” Ralston said. “We show that as species become more abundant, they are actually moving into new climate conditions, and declining species are disappearing from some of the climate conditions they used to be found in.”
            The researchers compared data from Breeding Bird Surveys from 1980-82 and 2010-2012 for 46 species, and overlaid the climate conditions each species occupied during those years to establish their “climate niche breadth.”
            Using this methodology, Ralston found, for instance, that the wood thrush, a close relative of the American robin, declined in population by about two percent each year for the last 30 years, and during that time it also showed a 7.5 percent decrease in its climate niche breadth. Grasshopper sparrows, a species of conservation concern due to loss of habitat and a resulting decline in population, have experienced a 43 percent decline in climate niche breadth.
            Many of the bird species that are increasing in abundance and increasing the breadth of their climate niche are species commonly found in suburbia. And Ralston said that there is an important lesson in this fact.
            “Anything we can do to increase bird populations – maintaining bird feeders, planting native plants, keeping cats indoors – can indirectly help those species respond to climate change.  A lot of the species that are doing best at tracking climate, like bluebirds and red-bellied woodpeckers, are those that are benefitting from human activities.”
            He said the implications for this study are significant.
            “Currently, when conservation biologists make predictions about how species will respond to climate change in order to make decisions about what habitats to protect, they are assuming that these species in the future will be occupying the same conditions as today,” Ralston said. “We show that that isn’t necessarily true. These future models might over-predict the conditions declining species will be found in. We’d be better informed if we try to include population trend and its effect on climate niche breadth when planning what habitats to protect.”

This article first appeared in Northern Woodlands magazine on May 10, 2017.

Thursday, May 4, 2017

Gypsy moths bring more bad news to region

            It’s almost gypsy moth caterpillar season again, a time of tree defoliation, caterpillar droppings raining down upon us, and a variety of other environmental impacts. Now comes the news that last year’s infestation may have also affected water quality in the region and will likely do so again.
            Gypsy moth caterpillars – along with winter moth caterpillars and forest tent caterpillars, but mostly gypsy moths – defoliated about 230,000 acres in Rhode Island last year, according to University of Rhode Island entomologist Heather Faubert, who coordinates the Plant Protection Clinic, making it the worst defoliation since
at least the early 1980s.  More than half of the state’s 400,000 forested acres were affected.
The defoliation also allowed sunlight into areas usually shaded by the forest canopy, which local ecologists said allowed sun-loving invasive plants to spread into the forest, denied native birds and small mammals protection from predators, and made it difficult for frogs and salamanders living on the forest floor to remain cool and moist.
Coupled with last year’s drought, it also resulted in what botanist Keith Killingbeck called “a muted display” of fall foliage.
The water quality implications from the caterpillars, reported last month by URI researcher Kelly Addy at a research conference at Brown University, were a coincidental result of a comparative study of how rainstorms affect stream water quality in forested, urban and agricultural watersheds. Addy said that sensors in Cork Brook in North Scituate picked up a “signature” of gypsy moths that lasted for many months.
“When you lose canopy cover, you have more sunlight hitting the streams, which warms up the water, and warm water cannot hold as much oxygen, so dissolved oxygen levels go down,” she explained.
Addy said that dissolved oxygen levels were further suppressed when large quantities of additional carbon – from caterpillar excrement, the caterpillars themselves, and fragments of leaves – dropped into the water from above.
“All that carbon fuels the organisms living in the water, causing them to flourish,” she said. “Suddenly you have more biomass of life in the streams, which sounds good, but they are then consuming more oxygen, and dissolved oxygen levels decline even more.”
In Cork Brook, dissolved oxygen was measured at 8 milligrams per liter in the summer of 2014 and 2015 but just 5 milligrams per liter last summer.
“At that level, you can start getting oxygen distress in sensitive species,” Addy said.
The low levels of dissolved oxygen in Cork Brook remained through at least last fall, when the sensors were removed.
“If gypsy moths are not a big issue this spring, then the water will likely recover,” she said. “But if it happens repeatedly, then the streams won’t bounce back as easily, and each spring it may remain low.
Unfortunately, gypsy moths are poised for another big year, with one caveat. “How bad it will be will depend somewhat on the weather,” said Faubert.
 In years when it’s rainy in May, the moisture abets several fungal diseases that get passed back and forth between gypsy moth caterpillars, causing the population to crash.
“But even if almost all of our gypsy moth caterpillars die off from the diseases, they don’t die until they’re already large caterpillars, so they will have already eaten a lot of leaves,” she said. “So we’re in for a lot of gypsy moth damage, regardless of the weather.”
That means the likelihood of many more dead trees, since the botany rule of thumb suggests that three consecutive years of defoliation will usually kill most trees. And even one year of defoliation of spruce or hemlock trees can kill them, Faubert said.
The only good news is that Faubert found fewer winter moth eggs this spring than in the past two years, so winter moth caterpillars – which typically hatch in early- to mid-April and feed on leaves and tree blossoms for about a month – may have a lesser impact on local trees this year than previously expected.

This article first appeared on on May 4, 2017.