2016 — Maui Invasive Species Committee (MISC)

Spiders in Hawaii, native and introduced

Posted on February 13, 2017 by Lissa Strohecker

Spotted orb weavers, like this one found in a remote rainforest on East Maui, are naturalized throughout the State. Their impacts on the ecosystem are not entirely understood, but they are not harmful to people. MISC file photo

As the calendar turns from September to October, giant webs appear overnight in yards upcountry. These are no ordinary spider webs. They are feats of engineering: perfect, spiraling webs two feet in diameter, strung 10 to 15 feet between trees or from the eves of the roof to the ground. At the center waits a crimson-legged spider ranging in size ¼ to ¾ inch long, not including legs. Every evening the weaver returns and rebuilds her web, much to the chagrin of early-rising humans who head out the door and face first into a spiderwebs.

The spotted orb weaver, known commonly as barn spiders, is an introduced spider in the genus Neoscona. They are one of approximately 205 species of spiders in Hawaiʻi, of which an estimated 77 species have been introduced by people—accidentally or unknowingly over the last few hundred years. The barn spiders are native to many parts of North America—in the east from Florida north to New England and in the west from Arizona, and south into Mexico.

As with most introduced spiders, they probably arrived hidden in cargo or plant material. Luckily, like some introduced species, their impact seems to be negligible. They are not particularly venomous and scurry away from people—though humans may scurry faster. Entomologist Mach Fukada with the Hawaiʻi Department of Agriculture first noticed them 20 years ago. He’s not worried but they may have an impact –contributing to an imbalance in the invertebrate food webs. The spider eggs are preyed upon by tiny native flies, and the presence of these introduced spiders may artificially increase the fly population, consequently increasing predation on native spiders.

Happy face spiders are native to Hawaii, one of 126 species that resulted from 13 original founders that arrived in the islands without the help of humans. Photo by Nate Yuen

The spiders native to Hawaiʻi are endemic – all 126 species are found nowhere else in the world but the Hawaiian Islands. The fact that spiders made it to Hawaiʻi without the help of humans is remarkable

Native spiders colonized the islands by drifting here on the wind courtesy of the tiny spider parachutes attached to their young; some even arrived riding debris across the ocean, a few may have come tucked among the feathers of a bird. Thirteen species provided all the genetic material for the resulting in the 126 species native to the Islands, establishing at the rate of a species every 2,310,000 years.

Native spiders tend to live in areas unaltered by people; finding their home in rainforests and mountain tops. The happy faced spider is perhaps the most famous of these; she makes cameo appearances in children’s books and cartoons. She’s rarely seen by most people, living in remote rainforests tucked under a leaf.

Other introduced spiders like the orb weaver and her giant web are far more likely to be the spiders you see. The most common and infamous, cane spiders, garden spiders, spiny backed orb-weavers (often called crab spiders), and false funnel spiders are the common ones, living among our houses and gardens with few impacts. Though they may be unloved, you can at least give spiders credit for keeping insect populations down: cane spiders devour cockroaches and even go after scorpions, hunting them down rather than waiting in a web. Farmers can thank spiders for helping to capture cabbage moths that devour crops. Webs are a secondary screen, capturing pesky mosquitoes.

Spotted orb weavers are a recent arrival to Hawaii, but not harmful. There are a handful of introduced arachnids that can be dangerous: black widows and brown violin spiders. MISC file photo

All spiders have a venomous bite (that’s how they subdue their dinner) but only a few introduced arachnids are harmful. Black widow spiders and the brown violin spider are both present in Hawaiʻi and fairly widespread and dangerous. They hide in dark crevices and avoid people when they can, but their presence warrants wearing gloves when moving wood and other material stored outside.

The introduced spiders present in Hawaiʻi are too widespread to be controlled by any organization or agency. Even black widows are so widespread that they are past the point of control. According to Fukada, spiders—cryptic and often hiding from people—are usually widespread and past the point of eradication before anyone notices them. The best time to stop a harmful spider is before it arrives. A strong, well-funded Department of Agriculture, staffed to inspect incoming cargo, can help as can buying locally.

Interested in what you have around your house and garden? You can find good information and identification help for some of the common spiders online at http://www.spiders.us/species/filter/hawaii/ and find additional resources for identifying poisonous spiders here: https://howigetridof.com/spider-identification/

Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.

Originally published in the Maui News on November 13th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Sunscreen, coral reef bleaching, and invasive algae

Posted on January 23, 2017 by Lissa Strohecker

The white coral heads at Molokini on Maui are bleached, suffering from the loss of their photosynthesizing partners, zooxanthellae. Caused by increased water temperatures, this phenomena is something coral can recover from when water temperatures drop. Photo courtesy of the State of Hawaii – Department of Land and Natural Resources -Division of Aquatic Resources.

Maui’s coral reefs are in trouble. Many of the hazards are complex and global – climate change and ocean acidification, for example—but there is a simple step we can take to protect coral: read the label on our sunscreen. Every day Maui residents and visitors leave an estimated 55 gallons of sunscreen in the water around the island. Though ocean going residents and visitors may be doing the right thing by protecting their skin, many of the sunscreens used contain reef-damaging compounds.

“If someone showed up and dumped a barrel of chemicals into the ocean, you’d call the EPA,” explains Jeff Bagshaw of the Department of Land and Natural Resources. Bagshaw oversees public outreach and education for the ‘Āhihi Kīna‘u Natural Area Reserve on Maui. He and his team of volunteers are reaching out to the community about the impacts of sunscreen on the reef.

Corals suffer in two ways: first, the active ingredient in many sunscreens, oxybenzone, affects the DNA function in coral cells; mature corals end up sterile while coral larvae are deformed and unable to attach to rocks and form more reef. Secondly, oxybenzone causes juvenile corals to encase themselves in their own skeleton where they starve.

Chemicals in sunscreen also increase the rate of coral bleaching. Normally, coral bleaching occurs when seawater reaches temperatures of 87-88 degrees. Corals then expel their zooxanthellae, symbiotic invertebrates that give corals both color and food through photosynthesis. Oxybenzones, avobenzones, and similar chemicals protect us from UV rays by absorbing light. When these chemicals end up on the reef, they continue to absorb light and “heat up” corals, essentially lowering the coral bleaching temperature by nine degrees to 78-79.

In ‘Āhihi Bay, these chemicals have been found at 14 times the “safe” level for coral to survive. Elsewhere in Hawaii, levels are 40 times greater than what coral can tolerate. Bagshaw estimates 30% of the corals in and around ‘Āhihi experienced dramatic bleaching last summer. Some of these coral heads are 500 years old.

A healthy reef can recover from an episode of coral bleaching, but many of the reefs around Maui are already weakened by invasive algae. As reefs bleach these invaders move in, capitalize on stressed corals and smother their healthy neighbors. Over time, the skeletons of the reef break down to rubble.

Coral reefs are critical to a healthy and functioning ocean ecosystem. Like the ohia in the rainforest, corals are keystone species, essential to the function of the ecosystem. Corals provide habitat for fish and support marine food webs. “If we lose coral we lose fishing, surfing, even the structure of our shoreline,“ says Bagshaw.

Protecting your skin from sunburn is important—just use alternatives to chemical-based sunscreens. Widely available mineral-based sunscreens are safe for the reef. Look for sunscreens with the active ingredients of zinc oxide or titanium dioxide and use those formulated for use in water. Rash guards and wets suits are a great form of sun protection and minimize worries about “gaps” when applying sunscreen to hard-to-reach places. Read labels closely. “Reef-safe” doesn’t necessarily mean safe for coral as there are no official guidelines for labeling a product as reef-safe.

Sunscreen is only one of 3500 products that contain oxybenzone and oxybenzone-like chemicals. Can’t remember the name? Heed this simple advice: “If you can’t say it, don’t spray it” says Bagshaw.

For more information on sunscreens and reefs, stop by the ‘Āhihi Kīna‘u Natural Area Reserve or check out posts on the reserve’s Facebook page: Friends of ‘Āhihi Kīna‘u. You can also help educate others about reefs and ocean life: contact Jeff Bagshaw at (808)264-7891 to join the reserve’s team of educational volunteers.

Originally published in the Maui News on September 11th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Pines threaten Haleakalā

Posted on November 16, 2016 by Lissa Strohecker

Forest Starr removes a pine sapling as part of the effort to protect Haleakala Crater. Only few species of pines are invading Haleakalā: Pinus radiata (Monterey pine), Pinus patula (Mexican weeping pine), and Pinus pinaster (maritime pine). Photo courtesy of Forest and Kim Starr

Haleakalā Crater is a rainbow of cinder, unlike anyplace else on earth. The result of millions of years of eruption of a stop and start volcano. At its greatest height, Haleakalā reached between 13,500 to 14,500 feet into the sky. When eruptions paused, the wind and rain went to work sculpting the crater, then it erupted again. Today, this history is laid bare for all to see. The plants and animals that live in this environment equal the geology, both in rarity and beauty. Haleakalā National Park is home to more threatened and endangered species than any other national park in the United States.

“…the tie-ribs of earth lay bare before us. It was a workshop of nature still cluttered with the raw beginnings of world-making.” wrote Jack London about Haleakalā Crater. Photo by Forest and Kim Starr.

It’s not only the natural history that makes Haleakalā Crater unique. It ranks as the quietest place on earth, a notable distinction in our busy bustling world. For the most part, Haleakalā Crater today would be recognizable as the same landscape, with most of the same vegetation, as it appeared to the early Polynesians that honored the crater as a the Wao Akua, realm of the gods; the same erosional depression that inspired Jack London to write “the tie-ribs of earth lay bare before us. It was a workshop of nature still cluttered with the raw beginnings of world-making.”

Few places remain so untouched today. Keeping the crater in a comparatively pristine state takes many hands. Miles of fence keep out the feral pigs and goats that once trampled the crater, but invaders still come, as seeds from invasive plants blown on the wind or hitchhiking on vehicles and clothing.

Today, the sanctuary of Haleakalā, the workshop of nature, is at risk of being lost underneath a blanket of pine trees. “Removing pines from the crater is our highest priority in terms of invasive plant control work in Haleakalā National Park,” explains Woody Mallinson, the Natural Resource Program Manager at Haleakalā National Park.

Kim Starr stands by a pine sapling in Haleakalā Crater. If these pines are not removed they will take over, leaving no room for the silversword and other plants an animals found only on Haleakalā. Photo by Forest and Kim Starr

Between 1910 and the 1940’s, well-intentioned territorial foresters planted pines on windward and leeward sides of Haleakalā, just west of the Koʻolau Gap, in Hosmer’s grove, and Polipoli to stop erosion and provide timber. A handful of those pine species turned out to be invasive. Over the next century they became increasingly widespread. Occasionally seeds found a way into Haleakalā, growing in the cinder soil. Park crews routinely removed them. They pulled 22 pines between 1982 and 2006.

But in 2007, a natural disaster spurred an explosion in pine seed germination. The pine plantation in Polipoli caught fire and the resulting flames burned over 600-acres on the southwestern slope of Haleakalā. The fire fighters who fought the blaze hadn’t seen anything like it in Hawaiʻi. Wildfires here typically spark in grasslands, but a summer drought left the forest of Polipoli primed for a forest fire. Pines, rich in natural oils and pitch, burn hot and flames blazed high above Kula.

The heat of the fire triggered the release of millions of pine seeds from inside their waxy cones. This natural response helps pines recolonize after a forest fire. It’s highly effective, and it has helped the pines colonize Haleakalā as well. Pines can be relatively slow growing, but they’ve managed to take over 2,200 acres of cliff walls and have the potential to invade about 18,000 acres of the Park. Since 2007, crews removed over 81,000 pines from the crater floor and walls, they estimate another 3,500 pines are creeping up the steep cliffs of the crater.

Pine saplings cascade down the rim of Haleakalā Crater. A 2007 forest fire in the Polipoli pne plantation spurred the germination of hundreds of thousands of pine seeds, carried on the wind into the crater. Photo by Forest and Kim Starr.

Pine saplings cascade down the rim of Haleakalā Crater. A 2007 forest fire in the Polipoli pine plantation spurred the germination of hundreds of thousands of pine seeds, carried on the wind into the crater. “If left unaddressed, the entire crater could be converted into a pine forest” Explains Woody Mallinson. Photo by Forest and Kim Starr.

“If left unaddressed, the entire crater could be converted into a pine forest. The result would be a landscape unrecognizable as compared to what we know today, with little to no habitat for endemic and endangered species. It would be a catastrophic ecosystem displacement,” explains Mallinson.

If the crater were to become a pine forest, the likelihood of future fires would increase. The combination of the dry arid climate, frequent winds, and fuel-rich pines could combine with disastrous results, especially for native Hawaiian species not adapted to fire.

Haleakalā National Park, in partnership with The Nature Conservancy, East Maui Watershed Partnership, Hawaiʻi Department of Land and Natural Resources and other conservation agencies are working to remove the pines, both inside and out of the park boundaries. Their efforts are helping to reduce the density of pines and protect Haleakalā.

You can participate. Join volunteer groups working with the Friends of Haleakalā on trips to remove pine trees from around Haleakalā Crater. Check their website for more information: www.fhnp.org

Lissa Fox Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.

Originally published in the Maui News on August 14th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Leafless on Maui: eucalyptus branches bare thanks to insect pests

Posted on October 3, 2016 by Lissa Strohecker

The eucalyptus snout weevil. Photo by Forest and Kim Starr.

In 2004, University of Hawaii (UH) entomologist Will Haines was visiting his parents in upper Haʻikū when he saw an unfamiliar yellow and green worm-like creature munching on eucalyptus leaves. Eucalyptus have few pests in Hawaiʻi, so this was a strange find. The oil-rich plants are virtually inedible to most insects.

A tortoise beetle larvae on eucalyptus. The larvae of both the tortoise beetle and snout beetle larvae dine voraciously on eucalyptus leaves. Photo courtesy of Forest and Kim Starr.

Haines is a researcher working at UH in the Plant and Environmental Protections Sciences. He’s curious by profession. At first he thought it was a caterpillar but couldn’t figure out what kind. It wasn’t until he found the adult, a homely weevil, that he determined that he wasn’t seeing a caterpillar, but rather the larvae of a eucalyptus snout weevil, Gonipterus platensis to entomologists, never before found in Hawaiʻi.

A blessing in disguise: the bluegum eucalyptus that line Piiholo Road are nearly dead after pest insects have spent over a decade munching their leaves. These eucalyptus are invasive, but their devastation will likely mean power outages and detours. MISC file photo.

Fast forward twelve years and many of the eucalyptus upcountry sport bare sticks where new growth should be. The snout weevil is only part of the reason. Another leaf-eating insect, the eucalyptus tortoise beetle (Paropisterna m-fuscum) is likely also responsible. The leaf-eating insects are native to Australia but have been found widely in California and may have arrived from the U.S. mainland.

New growth seems to be the most appetizing for these leaf-eaters and soon enough, trees feature bare branches where they should have new leaves. As older leaves die they aren’t replaced and the eucalyptus dies back. Plant diseases are also found on affected trees, possibly taking advantage of the ailing trees. The tree most affected appears to be Eucalyptus globulus, bluegum eucalyptus. Other species of eucalyptus are affected to a lesser extent.

Hawaii is the adopted home to over 90 species of eucalyptus, with bluegum being one of the most common. Fast-growing and remarkably tall, up to 200’, they were introduced in the mid-1800’s and used as boundary markers for pasture land, timber, wind breaks, and erosion control. On Maui, the State planted over 4,000 bluegum eucalyptus trees between 1910 and 1940, but private landowners and ranches have added to the total. As of the mid-1980’s there was an estimated 100 million board feet of bluegum eucalyptus, much of it along roadsides. Bluegums are fast growing and quick to spread, characteristics thought desirable when they were initially introduced.

A eucalyptus tortoise beetle and eggs in the foreground. Photo courtesy of Will Haines.

Most species of eucalyptus are invasive. The massive, water-laden trees are prone to falling in wind storms, even when healthy. But the thought of miles of roads lined with dying trees is concerning, particularly for residents along the roads. Power outages and detours are the likely outcome, probably more common than they are now. Then again, some of these giants may fall peacefully, dropping to the ground limb by limb, unable to catch the wind and sail over. Time will tell.

In the long-term, these insects may make eucalyptus less invasive. But until then, keep an eye on the eucalyptus near your homes, and it might be time to consider removal—particularly for the trees within falling distance of your house.

Originally published in the Maui News on September 11th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Koloa – the Hawaiian Duck

Posted on August 10, 2016 by Lissa Strohecker

This koloa landed at a water lily farm in Huelo. Most koloa on Maui are likely a mallard-koloa hybird, but this one, far from the Kanaha and Kealia Ponds may be related to Koloa released above Keanae. Photo by Masako Cordray.

About 1.5 million years ago a handful of stray mallard ducks made their way to the Hawaiian Islands. They came from North America and found a hospitable home in Hawaiʻi.

Mallards are remarkably adaptable: they are omnivorous and will eat virtually anything. They can make a home in saltwater, brackish water, and freshwater wetlands. No one knows exactly where in Hawaiʻi these avian settlers first arrived—but we do know that Maui was still Maui Nui at the time, still connected to Molokaʻi, Kahoʻolawe, and Lānaʻi. The conglomerate island was huge: at its peak, 1.2 million years ago, Maui Nui measured 5,640 square miles, 40% larger than modern day Hawaiʻi. It featured vast plains, marshlands, and a giant wetland, no doubt attractive to ducks and other water birds.

Isolation and time combined to create the conditions for something completely different; over generations, those few pioneer mallards evolved into a brand new species – common throughout the Hawaiian Islands, but found nowhere else in the world: the koloa, or Hawaiian duck. While mallards are loud and gregarious, koloa are quiet, and live in pairs or alone. Koloa are slightly smaller than their mallard ancestors. They like wetlands but also live in mountain streams, deftly navigating tight corridors and dense forests up to 10,000 feet. Koloa made their way into the legends of Hawaiʻi. When Imaikalani, a chief in Ka‘ū on Hawaiʻi Island, lost his eyesight, koloa acted as his scouts, alerting him with quacks about where his enemies hid in the forest.

In the mid-1800s these birds were common on all the main Hawaiian Islands except Kahoʻolawe and Lānaʻi. But as people filled the wetlands to make room for ball fields, car dealerships, and shopping malls, the koloa lost much of their nesting habitat. Introduced rats and mongoose stole koloa eggs and preyed on their young. By the 1950s, those impacts, combined with the onset of turn-of-the-century hunting, had caused our native ducks to disappear from Maui and most of the other main Hawaiian Islands. In the 1960s, koloa were listed as an endangered species; today, the largest population of koloa is found on Kauaʻi. There, they number fewer than 2,000 birds.

To help the species recover, the State of Hawaiʻi began reintroducing koloa throughout the Islands, drawing from the Kauaʻi population. In 1989, they released 25 birds on Maui at Kanahā Pond and in Piinau Valley above Keʻanae. Unfortunately, these koloa faced another obstacle to survival: genetic dilution.

In the late 1800s, non-native mallards were introduced to Hawaiʻi, this time in large numbers as game birds and pets. By 1980, healthy populations of feral mallards occupied many of the wetland areas throughout the state. Koloa and mallards long ago diverged into two distinct species but they can still mate and produce fertile hybrid offspring. Today, all of the koloa at Kanahā and Keālia ponds are hybrids. As generations pass, the hybrids are becoming less and less koloa. Eventually the unique genetics of the koloa could disappear entirely, rendering the species extinct.

These feral mallards are different from the migratory versions that show up in small numbers every year. The migratory birds are not in the mood for romance when they reach Hawaiʻi, so there is no chance of hybridization. The resident mallards are more domesticated and aggressive. They pose the greatest threat to the re-establishment of the koloa.

Today, the Kauaʻi population is home to a healthy population of pure koloa, thanks to efforts to remove rats and feral mallards at their breeding sites (koloa on Kauaʻi do not have to contend with mongoose). With continued protection, biologists are hopeful for the recovery of this species and its reintroduction throughout the state.

As for Maui, there are no immediate plans to reintroduce koloa. According to Dr. Fern Duvall, Maui Nui Program Manager with the Department of Land and Natural Resources, koloa may still occur in the mountain streams above Keʻanae, offspring of the birds released in 1989. To protect these rare Hawaiian ducks and ensure their successful reintroduction in the future, we must reduce existing mallard populations. Don’t feed mallards or feral ducks. If you happen to be a duck aficionado, keep your pets contained and their wings clipped. Never release your feathered friends into the wild.

Written by Lissa Strohecker. Originally published in the Maui News on July 10th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Uggh, slugs! Protect your garden and your health in light of rat lungworm disease

Posted on June 21, 2016 by Lissa Strohecker

Hawaiʻi is a gardenerʻs paradise, but slug control is critical given the presence of the rat lungworm parasite. Photo by Forest and Kim Starr

Rat lungworm disease: It may be rare but it’s memorable–like a horror movie come to life. Nightmarish tales of muscle spasms, temporary paralysis, and comas stemming from rat lungworm infection circulate on the news and the coconut wireless. Most cases in the Islands have been on Hawaiʻi Island but a few have occurred on Maui.

Humans are an accidental host for the rat lungworm nematode, but ingesting the nematode can have severe consequences. Graphic by Centers for Disease Control.

Rat lungworm is a parasitic nematode that—as you might guess from its name—infects the lungs of rats. If the parasite stayed in the rat, few of us would be concerned, but because part of the nematode’s complex and bizarre life cycle occurs in other common animals, people are at risk. Eggs laid in a rat’s lungs hatch and the microscopic larvae travel through the rat’s digestive tract, ending up in the animal’s poop. Mollusks such as slugs and snails feed on this, allowing the nematode to develop further inside its second host. When infected mollusks are eaten by a rat, the parasite travels first to the rat’s brain, then to its lungs, and the cycle repeats.

Unfortunately, slugs end up on the menu for other animals, humans included. Gardening in Hawaiʻi means dealing with cryptic, slithering pests, which often find their way into the harvest. A tiny slug tucked in a fresh batch of greens is easily overlooked.

“Don’t eat out of the garden without first washing the produce,” cautions Lynn Nakamura-Tengan, an extension educator with the College of Tropical Agriculture and Human Resources on Maui. She specializes in food safety and nutrition.

Always wash produce to remove any stowaway slugs that could carry the rat lungworm parasite. Photo by Forest and Kim Starr.

Eating a stowaway slug can come with serious consequences. If the slimy pest that slipped into your salad or smoothie carries nematode larvae, you become an accidental host. The larvae will travel through the bloodstream to the brain, but in humans they go no farther. The larvae continue developing as they crawl through the brain and eventually die—in the process, they trigger an infection causing eosinophilic meningitis, a swelling of the lining around the brain. The number of nematode larvae consumed determines the severity of the infection. Signs of rat lungworm disease range from flu-like symptoms, muscle spasms, and headaches, to temporary paralysis, nerve damage, coma, and even death.

Infected slugs or snails can climb into catchment tanks and drown, releasing microscopic nematode larvae that float around in the water and remain infectious for up to 3 days. If people use untreated catchment water for drinking or for brushing teeth, they can contract the disease.

The first cases of rat lungworm disease in Hawaiʻi occurred in the 1960s. Infections have recently spiked in the Puna area of Hawaiʻi Island. One reason is the presence of a semi-slug—a small slug with a partial shell that is invading Puna. The semi-slug’s life cycle and behavior may lead to a higher concentration of nematode larvae and a higher risk of passing the disease on to people.

That said, many mollusks common on Maui can carry the rat lungworm larvae, including giant African snails, golden apple snails, and the Cuban slug. Even the slime trail left behind can carry the parasite, though slime is not as likely a source of infestation.

Once a person contracts rat lungworm, there is no known treatment, therefore prevention is the key.

The Cuban slug is one of the common slugs on Maui and a carrier of rat lungworm. Photo by David Robinson of USDA-APHIS.

How can you avoid getting rat lungworm? Keep the critters away. “Be mindful of pest management,” advises Nakamura-Tengan. Regularly control rats, slugs, and snails. There are many methods, including those appropriate for organic gardens. If you hand pick slugs or snails, wear gloves and dispose of the slugs in the trash so pets don’t eat them. Dogs and horses have contracted rat lungworm disease, though no cases have occurred in cats. It’s unknown whether chickens can be infected, but studies from Australia show parrots are vulnerable to the disease.

Most importantly: hold off on the garden snacks until washing. “The cute picture of the kid eating a strawberry straight from the garden makes me cringe,” says Nakamura-Tengan. Wash, wash, and then wash your produce again, inspecting each leaf under running water as you go. A slug can often survive a hurried rinse in the sink. There is no benefit to using vegetable washes (dilute solutions of bleach, vinegar, or saltwater) to remove slugs – plain running water does the trick. Dispose of heavily contaminated produce or kill the parasite by cooking or freezing. If you have a catchment tank, take measures to keep slugs and snails out and filter water appropriately.

Keep gardening and growing your own vegetables – the presence of rat lungworm in Hawaiʻi is no reason to stop healthy eating practices. It is a good reason to be mindful about controlling pests and washing your produce- good habits in general.

Learn more:

You can help; survey your yard or farm for slugs and snails and report your findings here:

Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.

Written by Lissa Strohecker. Originally published in the Maui News on March 13th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Gold dust day geckos are only the latest moʻo to make Maui home

Posted on June 21, 2016 by Lissa Strohecker

Gold dust day geckos are here to stay. These colorful 5" long lizards are increasingly widespread on Maui and nothing to worry about. Photo by Eric Sonstroem, Flikr.

Gold dust day geckos are here to stay. These colorful 5″ long lizards are increasingly widespread on Maui and nothing to worry about. They can be distinguished from other lizards by the sprinkling of gold dust along the side of their necks. Photo by Eric Sonstroem, Flikr.

https://www.643pest.org/

Geckos are ubiquitous throughout the Hawaiian Islands today, but that was not always the case. Though lizards can colonize islands by clinging to drifting trees and plant material, the Hawaiian archipelago’s extreme isolation in the middle of the Pacific Ocean likely prevented any terrestrial reptiles from reaching our shores. It was only after humans arrived in Hawaiʻi that reptiles and amphibians found passage aboard canoes, ships, and eventually planes. Thus began the waves of introduced geckos, skinks, frogs, and chameleons that came and spread throughout the Islands.

The first lizards stowed away with Polynesians in large oceangoing canoes. Mourning geckos, stump-toed geckos, tree geckos, Indo-Pacific geckos, snake-eyed skinks, moth skinks, copper-tailed skinks, and the now-extinct azure-tailed skinks were already established in Hawaiʻi when Captain Cook arrived.

Though it may be impossible to measure the impact these small lizards had, the arrival of voracious, insect-eaters in an ecosystem that evolved over millennia without lizards or amphibians would inevitably result in a decline in native insects. This is problematic for Hawaiʻi, which has tens of thousands of unique invertebrates—many of which exist nowhere else on Earth and have yet to be described by science.

The giant Madagascar day gecko was illegally introduced to the state. Any sightings of the large 12 inch long moʻo should be immediately reported to the Hawaii Department of Agriculture at 643-PEST (7378). Photo by MrTinDC, Flikr.

The eight Polynesian-introduced geckos and skinks are still present in Hawaiʻi, but a few recent introductions have stolen the spotlight. Common house geckos only showed up in the last 60 years or so. They most likely hitchhiked to Hawaiʻi in the 1940s in cargo moved around the Pacific. Aggressive and territorial, they’ve outcompeted mourning geckos and others for the prized perch near the porch light.

An even newer arrival seems to be outcompeting the house gecko: the gold dust day gecko. This exotic, 5-inch long lizard is hard to miss: it appears to be dressed for Mardi Gras in brilliant green with bright blue eye shadow, red markings across its nose and at the base of the tail, and a sprinkling of gold spots dusted along back of its neck. Active primarily during the day, this gecko is native to Madagascar and small islands off the coast of East Africa.

Rather than arriving as a stowaway as other geckos and skinks have, the gold dust day gecko was illegally smuggled in and released. The entire Hawaiian population stems from only eight lizards a University of Hawaiʻi student released near the Mānoa campus in 1974. Shortsighted lizard enthusiasts intentionally dispersed the geckos, which then colonized new areas on their own. Maui residents began seeing gold dust day geckos creeping around Kīhei in the mid 90s. The lizards now populate landscaped yards throughout South and Central Maui and are becoming common Upcountry.

Gold dust day geckos eat insects: cockroaches, ants, flies, beetles, and spiders, but they also have a sweet tooth and lap up nectar from flowers or juice from ripe fruit. To date, they occupy roughly the same areas as other geckos, but the newcomer’s impact isn’t entirely understood. Their omnivorous diet may give them an advantage. While the colorful lizards seem harmless, they could be pressuring native ecosystems in ways not yet identified.

Orange spotted day geckos are another lizard to be on the lookout for. They are about 7 inches long and do not have the gold dust along their necks, rather have powder blue markings on their back amidst a pattern of orange bars. Photo by Herr Olsen.

While it’s too late to address the gold dust day gecko on Maui, there are two more species of day geckos to look out for. Both were illegally imported, and are only found in a few places on O’ahu. The orange-spotted day gecko and the Madagascar giant day gecko are both green with red markings, but lack the gold dusting. The orange spotted day gecko is slightly bigger than its gold-dusted cousin, reaching 7 inches in length, and the giant day gecko is a whopping 10-12 inches including tail. Any sightings of these new lizards should be reported immediately to the Hawaiʻi Department of Agriculture’s statewide pest hotline at 643-PEST or online via the Report A Pest website at 643PEST.org

Written by Lissa Strohecker. Originally published in the Maui News on January 10th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

What if there were no mosquitoes in Hawaiʻi?

Posted on March 18, 2016 by Lissa Strohecker

The Aedes aegypti mosquito is the primary vector of dengue worldwide. This species is not widespread in Hawaii. Photo by James Gathany,CDC.

The news is abuzz with mosquitoes these days; outbreaks of dengue fever on Hawaiʻi Island have us all a little more nervous when the high-pitched whine of a tiny pest reaches our ear. Mosquito-vectored viruses like Zika and chikungunya are on the horizon. Health officials in both South America and Hawaiʻi Island are scrambling to find ways to reduce mosquito populations and protect human health. Scientists are busy making nearly daily advances in the lab as well. All of the energy focused on removing these pests raises the question: how would the total removal of mosquitoes alter ecosystems?

There are over 3,500 species of mosquitoes in the world, of which only a few hundred bite. Mosquitoes and their larvae are food for fish, bats, birds, and dragonflies. Male mosquitoes don’t suck blood, they daintily sip nectar. In return, they help to pollinate some aquatic plants. But despite their service as prey and pollinator, many scientists think ecosystems would recover just fine if mosquitoes were gone–other insects could fill that niche, and we’d have one less vector for disease. Good news globally, but it only gets better for Hawaiʻi.

The Culex mosquito, larvae shown here, is the mosquito responsible for spreading avian malaria between introduced and native birds. Photo by James Gathany, CDC.

In Hawaiʻi, mosquitoes are food for native bats (ʻōpeʻapeʻa) and dragonflies (pinao). Would these species go hungry without this imported food source? Not in the least, explains Dennis Lapointe, an ecologist with the US Geological Survey who researches the ecological role of mosquitoes and birds in Hawaiʻi. “[Mosquitoes] are all non-native and everything that is native and endemic got along fine without them.” Some species of native damselfly larvae eat mosquito larvae, but they have other food sources.

The greatest ecological benefit would be to our native birds. Disease-spreading mosquitoes are a significant factor keeping iʻiwi,ʻ apapane, and other Hawaiian honeycreepers from flitting through the trees in your yard.

Aedes albopictus is widespread in Hawai’i and is a vector of Zika among other human diseases. Photo by James Gathany, CDC.

Mosquitoes first arrived in Hawaiʻi when sailors dumped a barrel of water containing larvae of the Culex mosquito into the wetlands that once surrounded Lahaina. The Culex mosquito became the vector that spread avian pox and malaria from non-native birds to Hawaiian forest birds, precipitating their decline. The native passerines lacked any resistance against these foreign diseases.

Today, our few remaining native forest birds are relegated to high-elevation refuges, protected by temperatures cool enough to keep mosquitos at bay. But protection could be short lived; current estimates of climate change indicate these refugia could disappear within 80-100 years.

If mosquitoes disappeared, so would the threat of avian malaria.

Currently, the fate of native birds is not foremost in our minds as human-health threats loom: the Aedes mosquitoes, which are also found in Hawaiʻi, are in the news now. A. albopictus, widespread throughout the Islands, is the primary carrier the Zika virus. A. aegypti, a mosquito found only in a few areas on Hawaiʻi Island, is the optimum carrier of dengue. Both Aedes species carry chikungunya. Both of these mosquitoes cause harm, with negligible environmental benefit.

Meanwhile, scientists are working on a tool to reduce mosquito populations without pesticides. Using genetic technology, a self-limiting gene is inserted into the DNA of male mosquitos. Reared in labs, the mosquitos are released to seek out and mate with females, but the self –limiting genes is passed along and their offspring die as

Mosquitoes breed in standing water, and removing breeding sites is one way to help reduce the density of mosquitoes. Photo by Mary Hollinger, NOAA.

larvae. The existing adults die off and are not replaced. Though years from being ready for release into the wild, scientists predict that these altered mosquitoes could be up to 99 percent effective in reducing mosquito populations, with no risk of developing resistance to pesticides. Each species of mosquito has to be targeted specifically, but Hawaiʻi has only a handful of invasive mosquitoes, all of which are non-native.

It’s something to think about: Hawaiʻi without mosquitoes, without the threat of dengue, Zika, or chikungunya. And, as an added benefit, Hawaiian forests with a few more native birds.

Until then, continue with mosquito-control efforts: dump standing water, treat bromeliads and other plants that hold water and mosquito larvae, and regularly apply repellent. These actions can help keep these blood-suckers at bay in your backyard.

Eliminate mosquito breeding sites: https://health.hawaii.gov/docd/files/2017/01/Eliminate-Mosquito-Breeding-Sites.pdf
Ecological role of mosquitoes: www.nature.com/news/2010/100721/full/466432a.html
Avian diseases in Hawaiʻi: https://mauiforestbirds.org/avian-disease/

Written by Lissa Strohecker. Originally published in the Maui News on February 14th, 2016 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.