Rat lungworm now in coqui frogs, bufos, even centipedes and crabs.

Coqui frog. Credit: U.S. Fish and Wildlife Service

This may read like something out of a Godzilla movie, but it has now become clear that rat lungworm disease has now teamed up with coqui frogs.

Researchers last year identified rat lungworm in the invasive, incredibly noisy frogs, and last month published a scientific paper on their findings.

Lungworm is spreading throughout the environment. Itʻs not only in rats, and of course humans and now coqui, but the scientists found it is also in centipedes, greenhouse frogs and even bufos.

The paper, "Occurrence of Rat Lungworm (Angiostrongylus cantonensis) in Invasive Coqui Frogs (Eleutherodactylus coqui) and Other Hosts in Hawaii, USA," was published in the Journal of Wildlife Diseases. The lead author is Chris N. Niebuhr of the USDAʻs National Wildlife Research Center Hawai`i Field Station in Hilo. Co-athors are Susan I. Jarvi, Lisa Kaluna, Bruce L. Torres Fischer, Ashley R. Deane, Israel L. Leinbach, and Shane R. Siers.

It still is not yet clear what role the new carriers play in transmitting the disease to humans, but it is clear that the rat lungworm is finding a pliant host in some of them: "In the frogs and toads, multiple tissue types were positive, including stomach and intestine, muscle, liver, heart, and brain, indicating larval migration," the authors wrote.

Rat lungworm is a nematode, a tiny worm that can cause severe neurological symptoms in humans. Here is the Hawai`i Department of Health website on the disease. 

Symptoms can go from nearly unnoticeable to severe pain and even paralysis.

Humans can be infected by, generally accidentally, eating it. Says the state Department of Health: 

"You can get angiostrongyliasis by eating food contaminated by the larval stage of A. cantonensis worms. In Hawaii, these larval worms can be found in raw or undercooked snails or slugs. Sometimes people can become infected by eating raw produce that contains a small infected snail or slug, or part of one. It is not known for certain whether the slime left by infected snails and slugs are able to cause infection. Angiostrongyliasis is not spread person-to-person."

The many source of human infection in the Islands seems to have been from unnoticed infected worms on salad greens, but as the nematode moves into new hosts, there could be new sources of infection.

The new hosts are referred to as paratenic or transport hosts. They are now believed to include frogs, toads, lizards, centipedes, crabs and other species. And while you might not directly eat these things, you or your pets could still be at risk.

The paperʻs authors wrote: " Although the species discussed here are not known to be intentionally consumed by humans in Hawaii, the ingestion of infected hosts could still pose a threat to other animals, because rat lungworm can infect both domestic and wild animals such as dogs (Canis lupus familiaris), horses (Equus caballus), and birds."

Rat lungworm in rats is excreted in their feces, which can be eaten by snails and slugs, as well as other species. Humans have been infected when eating uncooked greens with live slugs on them. 

With the disease now in frogs and toads and centipedes and the rest, new transmission could occur when uninfected rats eat infected specimens of those creatures. And with so many different carriers, it is possible new ways will emerge for humans to be impacted.

This is still an active area of research, the authors say, and more needs to be learned:

"Although our report of rat lungworm infections in frogs and centipedes implicates them as possible disease reservoirs, further investigations are warranted to better understand the role paratenic hosts may be playing in angiostrongyliasis transmission in Hawaii."

©Jan TenBruggencate 2020

Ancient botanical ink between far-flung Polynesian cultures, and why does Pitcairn keep showing up?

Polynesian voyagers visited nearly every island in the tropical and subtropical Pacific, and they colonized and remained on most of them.

But a remarkable few were abandoned, despite apparently having the resources to maintain a population. Pitcairn is one of those.

This remote high island in the eastern South Pacific is best known as the refuge that the Bounty mutineers and their Tahitian friends went to, to hide from the British navy. Pitcairn was uninhabited at the time. But it had been inhabited.

Canoe-sailing Polynesians had moved there a millenium ago, apparently thrived for 400 years, and then vanished. Like a sailing ship found drifting with no one aboard, its story is a mystery. Even today, as a British Overseas Territory, it has difficulty attracting people. An immigration site for Pitcairn is here. 

There is something eerie about Pitcairnʻs Polynesian history. Where did these islanders go? Did they abandon their island. Were they killed off by disease? Did war play a role? Or starvation?

One thing they may not have been is alone. 

In a major study of the Pacific-wide connections between island samples of paper mulberry (wauke, or Broussonetia papyrifera), which this blog covered in an earlier post, the plants collected on Pitcairn display deep genetic connections to Polynesiaʻs ancient past.

Wauke was a canoe plant—one of the critically important plants that all Polynesian voyaging canoes carried on their missions of colonization. It was important because it was the key plant for making fabric.

In studying the genetic differences and similiarities of wauke collected on different islands, the researchers found that Pitcairnʻs plants had strong genetic roots elsewhere in Polynesia.

For example, they found that "New Guinea is directly connected to Remote Oceania through Pitcairn."

There are distinct cultural differences between portions of Polynesia that were occupied at different times. For example, Fiji, Tonga and Futuna are an older Polynesian culture, which the authors call Western Remote Oceania (WRO). Islands like Niue, the Cook Islands, the Marquesas, the Austral Islands and Rapa Nui are understood to have been populated later. They are called Eastern Remote Oceania (ERO). New Guinea, in Near Oceania is outside that range and is considered even older in Polynesian history.

Yet, then there is Pitcairn.

"We found Pitcairn plants in a pivotal position between WRO and ERO. In addition, Pitcairn accessions linked with genotypes from New Guinea in Near Oceania," they write.

How to explain that? Pitcairn is physically in the newer area of Eastern Remote Oceania. Yet its wauke tells a different story, a story of ancient connections: "The link between these... groups was Pitcairn," the researchers write.

But the authors suggest that this does not suggest that Pitcairn was an ancient voyaging crossroads that maintained voyaging connections across thousands of miles of open sea. "We do not propose a direct migration route from New Guinea to Pitcairn," the authors write.

The explanation, they suggest, is simpler.

Pitcairn was occupied so long ago, and also abandoned so long ago, that it retained the ancient genetics of the wauke that the earliest voyagers carried with them.

"This relationship between samples from New Guinea and Pitcairn represents the survival of old genotypes on Pitcairn Island due to centuries of isolation after initial colonization by Austronesian speaking peoples. We suggest that these genotypes were probably lost on other islands that represent the intermediate steps of dispersal and migration," they write.

Hawaiʻi, the Marquesas, Rapa Nui (Easter Island) and Pitcairn are also linked genetically through wauke.

"The connections observed in our study through the genetic analysis of paper mulberry plants... show ties between Rapa Nui and Marquesas and between the Marquesas and Hawaii," the write.

Ultimately, the work confirms the conclusion that all Polynesia is connected, and that a thousand years ago, this stone age culture was tightly connected.

©Jan TenBruggencate 2019

Wauke tracks Polynesian voyaging routes: New genetic studies

Fiji kapa making. 

Credit: Andrea Seelenfreund

Genetic studies of one of the key canoe plants, wauke, appear to confirm Polynesian voyaging from west to east across the Pacific, but also identify key regions of voyaging.

Wauke, also known as paper mulberry or Broussonetia papyrifera, is the raw material for some of the best Hawaiian and Polynesian kapa or bark cloth. It also produces edible fruit. And interestingly, most of Polynesia only has female plants, while the Hawaiian Islands have both males and females.

How does that happen? The Hawaiian males apparently were brought to these islands after European contact. That will be reviewed later.  On all other Polynesian islands, all plants found today are female, but the research did find a couple of examples of male plants in samples from the early 20th century from the Marquesas and Rapa. 

This is confusing. The authors of one study on the subject said it could be that wauke males were included in early voyaging, and have since disappeared, leaving the plants to be reproduced only by human involvement. But there is an odd alternative possibility. The Broussonetia clan is known to occasionally undergo sex reversion, in which female plants may rarely produce male flowers, or males may change to females. 

Wauke

Credit: USDA, J.S. Peterson

Hawai`i is different from the rest of Polynesia because it still has male wauke. But those do not appear to be from early Polynesian introductions. Rather, the males apparently descend from a separate, non-Polynesian introduction to the Islands by 19th century Asian immigrants. The male wauke do not appear to have come through Polynesia, like the females. You can read more about the sexual distribution of the paper mulberry here. 

"Most paper mulberry plants now present in the Pacific appear to be descended from female clones introduced prehistorically," the authors of that paper write.

The dominant wauke stock in the Pacific appears to have originated in Taiwan, where, as in China and Indochina, it is native. But as a valued canoe plant, it was carried by Polynesian voyagers virtually everywhere they went. The plants are found not only in Hawai`i but at New Caledonia, Fiji, Samoa, Wallis and Tonga, in the Marquesas, the Society Islands, the Austral islands (Rapa), Pitcairn and Rapa Nui or Easter Island.

Wauke is a dioecious plant, meaning that male and female flowers occur on different plants. Because the existing plants are all female, the Polynesian wauke can't reproduce itself, and needs human help being transported and being kept alive.

"In the absence of breeding populations, the spread (i.e. movement) of paper mulberry depends entirely on a continuous human cultural tradition of preserving, propagating and transporting the plant," wrote the authors of the paper cited above.

In a new paper, many of the same authors, add to the story of the wauke. The latest paper, published this year in the journal PLOS One, is entitled "Human mediated translocation of Pacific paper mulberry [Broussonetia papyrifera (L.) L’He ´r. ex Vent. (Moraceae)]: Genetic evidence of dispersal routes in Remote Oceania."

The authors are from Chile, New Zealand and Taiwan. They include Gabriela Olivares, Barbara Peña-Ahumada, Johany Peñailillo, Claudia Payacan, Ximena Moncada, Monica Saldarriaga-Cordoba, Elizabeth Matisoo-Smith, KuoFang Chung, Daniela Seelenfreund and Andrea Seelenfreund. 

A Eurekalert press release on the study, which is simpler reading. 

The researchers conducted genetic studies on samples of wauke from 380 modern and museum samples from 33 islands across the Pacific.

They found that while all those female wauke are presumably clones of an original import, there is still some genetic diversity, and it can help understand migration patterns within the remote islands of Oceania.

"Our data detect a complex structure of three central dispersal hubs linking West Remote Oceania with East Remote Oceania. despite its vegetative propagation and short timespan since its introduction into the region by prehistoric Austronesian speaking colonists," wrote co-author Andrea Seelenfreund.

The three clusters where the wauke are most closely related to each other are: 1. Tonga and Fiji; 2. The islands of Samoa, Wallis and New Caledonia; 3. and then all of eastern Polynesia, including Hawai`i, Tahiti, the Marquesas Islands, Austral Islands and Rapa Nui.

There is evidence that Hawai`i had a more complex wauke heritage than other islands. Not counting the modern importation of male plants, it appears that traditional Polynesian strains of wauke came from both eastern Polynesia and Tonga in separate importation voyages. That adds an odd wrinkle to migration theory.

There seems to be a suggestion in the data that the wauke traveled between Taiwan and New Guinea, and from there into the rest of Polynesia. There are also suggestions that the wauke traveled on all voyaging canoes that were in the process of colonizing new areas, but after that were likely not on subsequent back-and-forth voyages.

"Crops important for survival and cultural reproduction were probably aboard all colonizing canoes, although probably not part of later inter-archipelago commercial networks or part of ritual exchanges of high valued objects, such as textiles, adzes, whale teeth, shells and other items between established settlements," the authors wrote.

© Jan TenBruggencate 2019

Last Hawaiian yellow-tipped tree snail dies.

 Achatinella apexfulva. Credit: DLNR

The tree snails of O`ahu were both common and famous.

So common that kids would walk into the hills above Honolulu and collect them to make leis. So famous that songs and legends referred to them.

Today, habitat change, predatory snails, rats, chameleons and other threats have made all of the many species rare. And now, another one, Achatinella apexfulva, has become extinct.

The last of his species, this guy was in captivity, and he made it into this year. He died New Year's Day 2019, at age 14.

This Achatinella was part of a gorgeous clan. The tree snail shells are just amazing, with whorls of gold and green, chocolate and café-au-lait, black and ivory. George himself was among the less stunning specimens, his palate limited to pales and browns.

Like his kin, he was famous. Hundreds of school kids have come to see him. He was named Lonesome George, after a lone tortoise from the Galapagos Island of Pinta. Tortoise George was also the last of his species, and he died in 2012. Read more about that George here. 

George was part of a small group of the last Achatinella apexfulva that were taken into captivity by the Snail Extinction Prevention Program. Researchers were able to get some to reproduce, but not enough to sustain the species. Their scientific name referred to the yellow tip on their shells.

George, a hermaphrodite like all of his species, could play both the male and female roles in reproduction, but apparently required a mate in order to reproduce. The state Department of Land and Natural Resources announced his demise.

More on the Snail program, along with some stunning imagery of the beautiful shells, is here. 

The tree snails and others in the Hawaiian native forest will be featured in an hour-long film, "Forests for Life," which looks at all the benefits of native forests and the threats they face. The film will be shown on KFVE-TV (K5), at 7:00 p.m. on Friday, Jan. 18th with a repeat on Monday, Jan. 21, 2019 at 8:00 p.m.

© Jan TenBruggencate 2018

Big Island fish evolving without geographic barriers: this is strange stuff

Arc-eyed Hawkfish, this one from Fiji in 2008. 

Credit: NOAA photo by Julie Bedford

If you isolate populations of animals and plants long enough, they can evolve into different forms, even different species.

That's been known for a long time.

In the Hawaiian Islands, we also have lots of evidence that the isolation doesn’t require long distances. A plant or insect in one steep-sided valley can have evolved into a unique species from its relatives in the next valley.

The valley itself may be sufficient to isolate the genetic flow, and allow each group to evolve independently.

But can species isolate themselves without geographic barriers? Apparently so, and you can find examples on Hawaiian reefs.

Researchers Jonathan Whitney, Brian Bowen and Stephen Karl, all of the Hawai`i Institute of Marine Biology studied arc-eye hawkfish (Paracirrhites arcatus) off the Big Island, where they found dark-colored fish on basalt bottoms and light-colored fish in coral habitats—all within a few feet of each other.

And it turned out that the dark colored hawkfish were more closely genetically related to dark hawkfish far away than they were to their light-colored cousins nearby. The fish apparently were isolating themselves voluntarily by their preferred habitat.

Whitney, Bowen and Karl published their research in the journal Molecular Ecology, under the title, "Flickers of speciation: Sympatric colour morphs of the arc-eye hawkfish, Paracirrhites arcatus, reveal key elements of divergence with gene flow." 

They wrote: "We observed greater genetic divergence between colour morphs on the same reefs than that between the same morphs in different geographic locations. We hypothesize that adaptation to the contrasting microhabitats is overriding gene flow and is responsible for the partial reproductive isolation observed between sympatric colour morphs."

Apparently, the light-colored fish on coral select their mates from among the other light-colored fish on coral, rather than from among the dark-colored fish on the basalt a short distance away. And vice versa.

"The combination of ecological, behavioural and now genetic  studies of the arc-eye hawkfish provides compelling evidence for partial reproductive isolation resulting from ecological barriers in the absence of geographic isolation."

The hawkfish have not been sufficiently isolated to have developed into separate species, but they seem to be on their way in that direction. And that's both interesting and strange, but may be a piece to a puzzle, the authors write:

"Whether complete reproductive isolation will develop between arc-eye colour morphs remains speculation. Regardless of the outcome, P. arcatus provides a rare case confirming that partial reproductive isolation can evolve in the face of continuous gene flow, bringing us one step closer to understanding the role ecological barriers play in initiating the early stages of speciation."

©Jan TenBruggencate 2018

Dying `Ōhi`a: Lots of research, perhaps some hope

Dead `ohi`a with live trees and uluhe.

Credit: DLNR

Lots of news organizations spread word that a variant of the Rapid `Ōhi`a Death fungus has been found on Kaua`i, but none told the larger story.

That story is the powerful effort that’s going on to save the tree that has been called the mother of the forest.

`Ōhi`a is really a remarkable part of the Hawaiian environment, growing in many environments from sea level to high mountains, and in many cases serving as the dominant canopy tree.

It feeds and houses insects. Those insects and the tree’s nectar feed birds. And it houses birds, both in its branches and in cavities in its trunk.

It is prominent in culture, common in legend, and it’s just plain gorgeous with its crimson and orange puffball flowers and widely varying leaf types. Buds can be reddish or orange or green, and shiny or covered with a frost of silver hairs.

“It is the foundation tree of our watershed,” said Bob Masuda, deputy director of the state Department of Land and Natural Resources.

As a community we despaired when there arrived a fungus, Ceratocystis lukuohia, which began killing trees by the thousands on Hawai`i Island. Many trees were infected and once infected, death was certain often in days to weeks. It was sometimes called `Ōhi`a Wilt, and sometimes more dramatically, Rapid `Ōhi`a Death.

It turns out that a small percentage of trees was also infected with a slower-developing related fungus, Ceratocystis huliohia. It could take months to years to kill a tree, often taking single branch systems before killing off the entire tree. 

Here's a piece on how they got their Hawaiian names.

That’s the one that has now been found on East Kaua`i. Not nearly as virulent as its spooky cousin, but still a problem for `ōhi`a. Foresters suggest it probably shouldn’t be called Rapid `Ōhi`a Death, because, well, it doesn’t progress so rapidly.

Both are examples of something called a vascular wilt—a fungus that clogs the tree’s ability to transfer water between roots and leaves

There are some interesting things about these diseases, including that they appear to have very different sources. The fast-acting one is most closely related to fungi in Latin America, while the slower one appears to be more closely related to Asian fungi.

And the slower-moving version may spread slowly enough that it was in the Hawaiian Islands first, but wasn’t recognized. There are lots of things that can kill `ōhi`a trees, lots of disease that can attack them—although none as aggressive as Ceratocystis lukuohia.

One of the big unanswered questions about both diseases is whether there is hope. Whether there are any examples of `ōhi`a trees that may be resistant—and thus could be used to repopulate the Hawaiian forest.

To help find that out, lots of research is underway, including aerial surveys on several islands to better understand the outbreak. Here’s one study on the aerial monitoring from the journal Remote Sensing. 

Pathologist Lisa Keith, of the USDA Pacific Basin Agricultural Research Service, said that researchers are growing seedlings of different varieties of `ōhi`a and infecting them with the fungus. So far, some are still surviving—perhaps a good sign, although they may just be heading downhill slower than others.

She and others are also working with different fungicides, which may not save an infected tree, but might keep a particularly valued tree alive longer. Others are working with other techniques to try to strengthen the trees so they can potentially survive infection.

It’s clear that humans are big carriers. If a tool like an ax, chain saw or machete cuts an infected tree, it can easily spread the disease if you cut into a second tree without disinfecting the tool. Any injury to the tree can be a highway for infection.

Scientists are studying the beetles that may be spreading the disease by boring into the trees.

And they’re trying to determine how effective the fungus is at being spread by wind.

And what if it’s not just those beetles, but other insects. Researchers have chunks of infected tree wood in netted containers, to watch what other insects might emerge over time.

If the disease is spread by wind, then perhaps you could limit the spread by cutting down a swath of trees downwind from an infected patch, to deny the fungus trees to spread to. Kind of like cutting a firebreak.  The state Division of Forestry and Wildlife is working on that technique.

Researchers are studying old photographs of the forest to try to determine what they can about disease in `ōhi`a over the years.

And scientists have developed quarantine measures to reduce the spread—like limiting the movement of infected wood.

The number of organizations working on this issue is impressive. It includes the University of Hawaiʻi at Mānoa College of Tropical Agriculture and Human Resources, the U.S. Pacific Basin Agricultural Research Center, USDA Forest Service Institute of Pacific Islands Forestry, the Department of Land and Natural Resources’ Division of Forestry and Wildlife, University of Hawaiʻi at Hilo, The Nature Conservancy, National Tropical Botanical Garden, Hawaiʻi Association of Watershed Partnerships, Coordinating Group on Alien Pest Species, the Big Island, Maui, Molokai, O'ahu and Kaua'i Invasive Species Committees, USFS Region 5 State and Private Forestry, USGS Pacific Island Ecosystems Research Center, Carnegie Airborne Observatory,  Hawai'i Invasive Species Council and Hawai`i Department of Agriculture -Plant Quarantine Branch.

Learn more about the disease here. 

A sign of hope is that not every tree in a diseased stand dies. But it’s not yet clear whether that’s because surviving trees might be resistant to the disease, or that they simply haven’t been infected yet.

That said, the `ōhi`a is so important to the Hawaiian environment that researchers and foresters hope to be able to identify resistant trees.

If they can find them, then the daunting task will be a massive statewide effort to replant these seminal trees throughout the Hawaiian forest.

© Jan TenBruggencate 2018

Cool Hawaiian science: blend up some healthy leaves, spray on sickly plants, and create healthy plants

We are not alone, and we can’t be.

Whether human or plant or other species, we all live by John Donne’s rule: “No man is an Island, entire of itself; every man is a piece of the Continent, a part of the main.”

(Image:  The native mint P. kaalaensis in flower, with fungal

infection (white spots on leaves). Credit: Geoff Zahn.)

University of Hawai`i researchers, in an elegant new piece of work, show that even plants in the garden depend on a community of other organisms to protect them. Some of these natural allies live in the soil and root, in the stems and leaves, and even on the stems and leaves.

In this case, working with a native mint called Phyllostegia kaalaensis, professor Anthony Amend and researcher Geoff Zahn found that they could transplant disease resistance into a plant that otherwise was a severe risk of fungal attack.

The mint, which was once thriving in the wild, has been extinct in the wild since 2015. The ones still living in nurseries were extremely weak--perhaps because they were sprayed regularly with fungicides to prevent fungus attack. The fungicide kept them alive but also kept them weak, said Zahn.

As long as the plants remained so vulnerable, there was little hope of restoring them to the wild, where they would immediately be killed off.

Healthy native mint in the wild. Credit: Vincent Costello.

All it took was to blend up (actually blend, in a blender) the leaves of a related wild plant, which presumably contained whatever protective organisms lived with the wild plant. The donor plant was a related endangered Hawaiian mint from Molokai, Phyllostegia hirsuta. 

They sprayed the blended stuff onto nursery plants. And the plants that had been given this “transplant” of beneficial organisms were suddenly able to fight off fungal attack. The beneficial organisms are called endophytes, which are forms of life like fungi and bacteria that live inside the plant. 

Here’s now the University of Hawai`i press release put it:

“They took leaves from a closely related wild that plant was healthy and contained a typical mix of endophytes, blended them into a smoothie and sprayed the mixture onto the leaves of (the native mint)  to see if beneficial microbes could be transplanted from one species to another. They then subjected these plants, along with a control group, to the deadly powdery mildew. The plants that received the microbial spray were able to resist disease, those that didn’t receive the spray soon died.”

The research is simply remarkable. Nursery plants, generally planted in sterile media, are “alone.” They don’t have their natural biological communities around them. And as a result they are severely vulnerable. 

In this case, Amend and Zahn weren’t sure which of the constituents of the blended spray did the anti-fungal work, so they tested for it.

“Using DNA barcode sequencing to identifying which species were inside leaves before, during, and after the disease, Amend and Zahn determined the beneficial fungus that was most likely responsible for protection from disease: the yeast Pseudozyma aphidis. Those treated plants did so well, that they have since been planted out in the wild, and now represent the only wild population of P. kaalaensis on the planet.”

Zahn said this yeast can live both on the leaf surface and inside the plant's tissues. When they prepared the leaves for blending, they cleaned the exterior, so the protective fungus came from inside the tissues of the hirsuta. 

The National Science Foundation and the Army funded the research. Anend and Zahn were associated with the University of Hawai‘i at Mānoa botany department and the O'ahu Army Natural Resources Program. Zahn has since moved on to Utah Valley University.

Amend continues the work in Hawai`i, and also works with University of Hawai`i researcher Nicole Hynson, who is studying, among other things, beneficial organisms in the roots of plants.

This remarkable research builds on a growing understanding of the relationship between diverse life forms. 

Some years ago, researchers were able to save an exceedingly rare native orchid on Molokai.

The orchid did poorly in captivity, and did poorly when planted out in the wild. But when it was planted in soil that had been inoculated with soil from places where it had once grown, it did fine.

Growing with the soil organisms on which it depended, it survived. Alone, it did not.

We’re not even going to go here into the relationships between humans and their gut organisms. But whether you go by “no man an island” or “it takes a village,” the message is clear.

 © Jan TenBruggencate 2017