Report to Kayangel State: 2015 Survey of Invasive Plant Species

Joel Miles
Palau Bureau of Agriculture
April 2015


This report is available as a PDF file: Report to Kayangel State: 2015 Survey of Invasive Plant Species 



Introduction

From April 6-9, 2015, a team of three people, accompanied by four employees of Kayangel State, surveyed all four islands of Kayangel Atoll to detect the presence of invasive plant species. The team was led by Palau National Invasive Species Coordinator, Joel Miles, who was accompanied by Ms. Lesley Vick and Mr. Jan Skovdam. The Kayangel State employees were K-PAN Director Mr. Asailee Yamada, and PA Rangers Robert Johnson, Weider Debengek, and Oriokel Daniel. On April 6 the team surveyed the islands of Orak and Ngerbelas. On April 7, we surveyed Ngeriungs and began to survey Ngcheangel. On April 8 and 9 we completed the survey of Ngcheangel Island. For Ngcheangel Island, we were able to compare our results with those of previous surveys in 2002 and 2008, but the other three islands had not previously been surveyed for invasive plants.

While in Kayangel, we also assessed damage done by the Coconut Rhinoceros Beetle (CRB/Chermel a Lius), and set up traps on Orak, Ngerbelas, and Ngcheangel to monitor the population of this very destructive invasive pest of coconuts and other plants.

We also assessed the impacts of two destructive invasive insect pests which have been reported by residents as destroying papaya trees and other plants.

A meeting with the community on Wednesday evening, April 8, was very well attended. At this meeting, we shared the results of the survey and gave the community our recommendations which are reported below.

Invasive Plant Survey Results

Orak and Ngerbelas

I am pleased to report that no invasive plants were found on either of these islands.

Ngeriungs

Nine species of suspected invasive plants were found in the disturbed area at the northern end of Ngeriungs; no invasive plants were found in the undisturbed portion of the island. Most of the nine suspected invasives were tentatively identified, but a few need further identification by experts. Specimens were taken of all these plants and they have been deposited with the herbarium at Belau National Museum, whose staff will assist with identification. Table 1 below lists the suspected invasive plants found on Ngeriungs.

Table 1. Suspected invasive plant species present on Ngeriungs

Scientific Name

Common Names (abridged)

Family

Habit

Cenchrus polystachios

English: Mission grass; Palauan: desum

Poaceae

grass

Cyperus rotundus

English: purple nutsedge, nutgrass; Palauan: tamanengi

Cyperaceae

herb

Dactyloctenium aegyptium

English: beach wiregrass, button grass, coast button grass, comb fringe grass, crowfoot grass, duck grass, finger comb grass

Poaceae

grass

Digitaria sp.

Need to identify species

Poaceae

grass

Eleusine indica

English: goosegrass, wiregrass, goose foot, crow's foot, bullgrass; Palauan: deskim, kelelamalk, keteketarmalk

Poaceae

grass

Portulaca oleracea

English: pigweed, purslane; Palauan: bungaruau ra sers

Portulacaceae

herb

Spermacoce ovalifolia

English: broadleaf false buttonweed

Rubiaceae

herb

Unknown

Need to identify

?

herb

Unknown

Need to identify

Fabaceae

Shrub or tree

Ngcheangel

For Ngcheangel Island we conducted the survey using the tables from the 2008 survey as checklists: if a plant seen in 2008 was found, it was checked off the list. Species which were not on the 2008 list were added as new species in a new table. Species in Table 2 and Table 3 below which were found in this survey are highlighted in green. Species not found are highlighted in yellow. Species known to be no longer present are highlighted in blue. In addition to the invasive plants in these two tables, an additional 11 invasive plants were found during this survey: these plants are listed in Table 4.

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Table 2. Invasive plant species of environmental concern present on Ngcheangel 2008 & 2015

Scientific Name

Common Names (abridged)

Family

Habit

Abelmoschus moschatus

English: fautia, musk mallow, musk okra; Palauan: gongul

Malvaceae

herb

Acacia auriculiformis

English: Papuan wattle, earleaf acacia, northern black wattle, ear-pod wattle

Fabaceae

tree

Asystasia gangetica subsp. gangetica

English: Chinese violet, Philippine violet, coromandel

Acanthaceae

herb

Axonopus compressus

English: blanket grass, carpetgrass

Poaceae

grass

*Ceiba pentandra

English: kapok tree, silk-cotton tree, pacae; Palauan: kalngebárd, kalngebard, kerrekar ngebard

Bombacaceae

tree

Cenchrus echinatus

English: burgrass, sand-bur, southern sandbur, Mossman River grass (Australia)

Poaceae

grass

Clerodendrum buchananii var. fallax

English: red clerodendrum, pagoda-flower; Palauan: but a cherechar, butcherechár, butecherechar

Lamiaceae

shrub

Clerodendrum quadriloculare

English: bronze-leaved clerodendrum; Palauan: kleuang

Lamiaceae

shrub

Dactyloctenium aegyptium

English: beach wiregrass, button grass, coast button grass, comb fringe grass, crowfoot grass, duck grass, finger comb grass

Poaceae

grass

Digitaria ciliaris

English: Henry's crabgrass, smooth crabgrass, tropical crab grass, large crab grass, southern crabgrass, fingergrass, summer grass

Poaceae

grass

Eleusine indica

English: goosegrass, wiregrass, goose foot, crow's foot, bullgrass; Palauan: deskim, kelelamalk, keteketarmalk

Poaceae

grass

Erigeron bellioides

English: bellorita, fleabane daisy

Asteraceae

herb

Muntingia calabura

English: jam tree, strawberry tree, Jamaican cherry, Singapore cherry, Panama cherry, Panama berry, ornamental cherry, calabura, sirsen; Palauan: budo

Tiliaceae

tree

Paspalum conjugatum

English: T grass, ti grass, sour grass; sour palpalum, buffalo grass, carabao grass, Hilo grass (Hawai'i); Palauan: udel ra ngebel

Poaceae

grass

Pilea microphylla

English: artillery plant, gunpowder plant, pistol plant, rockweed

Urticaceae

herb

*Pseuderanthemum carruthersii

English: false eranthemum

Acanthaceae

shrub

*Samanea saman

English: monkeypod, rain tree, saman

Fabaceae

tree

*Tecoma stans

English: yellow bells, yellow-elder, yellow trumpetbush

Bignoniaceae

small tree

*Thevetia peruviana

English: yellow oleander, be-still tree, lucky nut

Apocynaceae

small tree

*Thunbergia grandiflora

English: Bengal trumpet, blue trumpet vine, clock vine, skyvine, large-flowerd thunbergia; Palauan: bung el etiu

Acanthaceae

vine

*Timonius timon

English: liberal (Palau)

Rubiaceae

tree

*Tradescantia spathacea

English: oyster plant, boat plant, boat lily, moses in a boat; Palauan: kobesos

Commelinaceae

herb

Tradescantia zebrina

English:  wandering zebrina, wandering jew, inchplant

Commelinaceae

herb

Turnera ulmifolia

English: yellow alder, sage rose, West Indian holly, ramgoat dashalong

Turneraceae

shrub

*Cultivated

Table 3. Other invasive plant species present on Ngcheangel, 2008 & 2015

Scientific Name

Common Names (abridged)

Family

Habit

Acalypha lanceolata


Euphorbiaceae

herb

Bidens alba

English: beggar’s tick, Spanish needle, cobbler's pegs, romerillo

Asteraceae

herb

Blechum pyramidatum

English: green shrimp plant, Browne’s blechum

Acanthaceae

herb

*Capsicum frutescens

English: bird pepper, bird's-eye chili, bird's-eye pepper, hot pepper, red chili, spur pepper, Tabasco pepper; Palauan: meringel

Solanaceae

herb

Chamaesyce hirta

English: asthma plant, garden spurge, pill-bearing spurge, hairy spurge; Palauan: udall

Euphorbiaceae

herb

Chamaesyce hypericifolia

English: beach spurge, graceful spurge; Palauan: karkar, kerkar

Euphorbiaceae

herb

Eclipta prostrata

English: eclipta, false daisy, swamp daisy, white eclipta; Palauan: deberebelela tengadidik

Asteraceae

herb

*Malvaviscus penduliflorus

English: Turk's cap

Malvaceae

shrub

Mirabilis jalapa

English: beauty of the night, false jalap, four o'clock, marvel of Peru

Nyctaginaceae

herb

*Moringa oleifera

English: horseradish tree, drumstick tree, ben nut, morango; Palauan: malungkai

Moringaceae

tree

Peperomia pellucida

English: peperomia, pepper elder, rat's ear, shiny bush, silverbush; Palauan: rtertiil

Piperaceae

herb

Phyllanthus amarus

English: six o'clock, sleeping plant; Palauan: ukalla ruchel

Euphorbiaceae

herb

Portulaca oleracea

English: pigweed, purslane; Palauan: bungaruau ra sers

Portulacaceae

herb

Solenostemon scutellarioides

English: coleus

Lamiaceae

herb

Spermacoce ovalifolia

English: broadleaf false buttonweed

Rubiaceae

herb

Spermacoce remota

English: buttonweed; Palauan: okula beluu

Rubiaceae

herb

Stachytarpheta jamaicensis

English: bastard vervain, blue porterweed, Brazilian tea, Jamaica vervain, joee, light blue snakeweed; Palauan: louch beluu

Verbenaceae

herb

*Swietenia macrophylla

English: Honduras mahogany, large-leaved mahogany, mahogany

Meliaceae

tree

Synedrella nodiflora

English: Cinderella weed (Australia), porter bush, synedrella

Asteraceae

herb

*Tabebuia heterophylla

English: pink tecoma, pink trumpet tree, white cedar

Bignoniaceae

tree

*Cultivated

Table 4. Additional invasive plant species found on Ngcheangel in 2015

Scientific Name

Common Names (abridged)

Family

Habit

Alternathera sessilis


Amaranthaceae

herb

Cyprus rotundus

English: purple nutsedge, nutgrass; Palauan: tamanengi

Cyperaceae

herb

Digitaria sp.

Needs to be identified

Poaceae

grass

Leucaena leucocephala

English: tangantangan, haole koa; Palauan: telengtungd

Fabaceae

tree

Melia azedarach

English: chinaberry, pride of India

Meliaceae

tree

Senna occidentalis

English:

Fabaceae

shrub

Sphagneticola trilobata

English: wedelia, Singapore daisy; Palauan: ngesil era ngebard

Asteraceae

groundcover

Syngonium podophyllum

English: goosefoot, arrowhead vine

Araceae

vine

Stachytarpheta cayannensis

English: rat’s tail, snake plant

Verbenaceae

herb, shrub

Tridax procumbens

English: coat buttons

Asteraceae

herb

Turnera subulata

English: white alder

Turneraceae

shrub


Management Recommendations

2008 Recommendations

The following recommendation was made following the 2008 survey: “Only a small number of invasive species are present in Kayangel. Island residents should institute voluntary quarantine to prevent further introductions and promptly eradicate undesirable species when found.” Two plants in particular were singled out for special attention in Table 5 below.

Table 5. Recommendations from 2008 survey

Scientific Name

Common name

Comments and recommendations

Thunbergia grandiflora

bung el etiu, blue trumpet vine

Eradicate if still present.

Timonius timon

liberal

Eradicate if still present.

NOTE in 2015: Neither of the above two species was found in this survey. The liberal tree is known to be dead, and we viewed the stump. This tree reportedly never produced fruit and we found no seedlings/saplings; I suspect that it was a male tree. This is excellent news: this tree has transformed native forest on Angaur and Peleliu, and is known to be spreading north in the Rock Islands Southern Lagoon conservation area of Koror State. Care should be taken to ensure that this very invasive tree is not re-introduced to Kayangel State.

We did not find any bung el etui, but I recommend that residents continue to be vigilant and to remove this invasive vine if it is ever seen. I will provide photographs to state employees to assist in its identification.

2015 Recommendations

As noted n 2008, Kayangel State is fortunate to have very few invasive plants, relative to Koror and Babeldaob. This is due mainly to Kayangel’s relative isolation, but this isolation is changing with increased resident and tourist traffic. I therefore want to emphasize the recommendation for voluntary quarantine made in 2008: care must be taken by residents and visitors to prevent the introduction of any new invasive species through effective biosecurity. The state should consider adopting biosecurity legislation to ensure that your resources are protected.

Of the over 50 invasive plant species present in Kayangel State, I recommend that action be taken to control and, if possible, eradicate the seven species listed in Table 6 below. These seven species of plants are well adapted to grow in the soil and climate of Kayangel State, and can have serious impacts on agriculture and the natural environment of the atoll.

Table 6. Recommendations from 2015 survey

Scientific Name

Common name

Comments and recommendations

Clerodendrum quadriloculare

English: bronze-leaved clerodendrum; Palauan: kleuang

Take control actions to reduce size and density of infestations

Leucaena leucocephala

English: tangantangan, haole koa; Palauan: telengtungd

Eradicate if possible, or reduce population if eradication is not possible.

Melia azedarach

English: chinaberry, pride of India

Eradicate

Sphagneticola trilobata

English: wedelia, Singapore daisy; Palauan: ngesil era ngebard

Take control actions to reduce size and density of infestations, eradicate if possible.

Syngonium podophyllum

English: goosefoot, arrowhead vine

Take control actions to reduce size and density of infestations, eradicate if possible.

Turnera subulata

English: white alder

Eradicate

Turnera ulmifolia

English: yellow alder, sage rose, West Indian holly, ramgoat dashalong

Eradicate

Poisonous Plants

While conducting the survey, we found specimens of three poisonous plants, Datura, Chinaberry, and Oleander. In a meeting with the community on the evening of April 8 we recommended that all specimens of these plants be destroyed.

Coconut Rhinoceros Beetle (CRB/Chermel a Lius) Assessment and Monitoring

We assessed damage to mature coconut trees on three islands of the atoll: Orak, Ngerbelas, and Ngcheangel (Ngeriungs has very few coconut trees, so it was not assessed). We also set up bucket traps on these three islands for the purpose of monitoring the CRB population.

Damage Assessment

We scored the level of damage to at least 10 trees at eight sites (six on Ngcheangel and one each on Orak and Ngerbelas), using an assessment system developed by the Secretariat of the Pacific Community (SPC). The K-PAN Rangers are now capable of conducting this assessment every 3-4 months. This was the second such assessment conducted in Kayangel State; the first was conducted in December 2014. I am pleased to report that the level of damage is about the same or perhaps a little less now than in December, but it is too soon to conclude that there is no threat. It may be that monitor lizards (elub) on the islands are helping to prevent a more serious outbreak of CRB by eating the larvae of the beetles.

As described above, we only assessed damage to mature trees. We did not assess seedlings, but we observed that a number of newly-planted seedlings have been killed by the beetles. Residents of Kayangel State should observe their seedlings to see how serious this is; I can work with K-PAN to develop a method of monitoring such damage. In the meantime, I have recommended a method of protecting seedlings from CRB using small-mesh fishing net or garden netting, a method developed at the University of Guam. This method was shared with the community, and a small amount of netting was provided to K-PAN; one island resident offered to test it on her coconut seedlings.

Monitoring CRB Population

As noted above, we set up eight bucket traps to monitor the population of CRB. These traps use a scent, known as a pheromone, to attract the beetles, which are then trapped in netting over the top of the bucket. K-PAN Rangers will count the number of beetles in each trap every two weeks; over time we will be able to see whether the CRB population is increasing, decreasing, or remaining the same. NOTE: the traps are not effective for control of CRB; they are only for monitoring the population.

Mealybugs and Whiteflies

Kayangel residents reported the presence of white insects on the leaves of several types of plants; these have been particularly severe on papaya plants, and numerous papaya trees have died as a result. I inspected the papaya trees and several other plants and discovered two different insects. On the papayas, as well as plumeria (elilai era ngebard) and some other plants, the insect is the papaya mealybug. The good news is that I also discovered an insect that will control this mealybug (biological control), so it should be a matter of only a few months until this problem is resolved. I have given full information on this insect and its control to K-PAN and to the community.

The second insect I found is called the whitefly. This tiny insect is also controlled by another insect, and I expect that the numbers of whiteflies will also decrease in the coming months. They will not completely disappear, but their numbers should decrease enough that they will no longer cause serious damage.

Summary and Conclusions

I want to stress the importance of good biosecurity for Kayangel State. As noted above, Kayangel has very few invasive species compared to most of the rest of Palau, and it would be best to keep it that way. This can be done if residents and visitors take reasonable precautions, including inspecting all cargo before offloading. Kayangel State has developed a biosecurity plan with the support of Palau Conservation Society; this plan should be fully implemented in order to protect the community and environment of Kayangel.

Finally, I take this opportunity to thank K-PAN and the community for hosting us, and Lesley Vick and Jan Skovdam for their assistance in the survey.


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This page was created on 11 May 2017 by PT and was last updated on 18 May 2017 by PT.