Oahu Invasive Species Committee (OISC)

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Naio Thrips

Naio Thrips:

Naio thrips (sometimes called myoporum thrips) were detected on Oʻahu on November 23, 2018. Naio thrips attack our native Hawaiian naio tree (Myoporum sandwicense). These thrips are small sucking insects with feathery wings. They harm the naio by sucking the tissue out of the new leaves, causing severe damage, defoliation, and eventual death of the plants.

Our goal was to contain and eradicate these harmful pests by first removing all infested plants on the island and then removing naio in landscaping as they are harbors allowing thrips to spread. Over 900 plants have been removed since the detection, along with thousands of man hours spent in the field. Numerous land managers and private citizens have been cooperating with this effort and there has been much support to stop the spread of naio thrips in order to save the wild populations.

However, the large number of naio in landscaping and the ease with which thrips are dispersed, combined with the logistics of coordinating massive plant removal projects using limited resources has made it extremely difficult to stop their spread. In short, despite reallocating thousands of man hours to remove their food sources, the thrips moved faster than we could. The strategy has now moved from eradication to management.

Removing so much food for the thrips in the beginning of the outbreak slowed the spread and allowed us some breathing room to figure out a management strategy that we can use when the thrips eventually make it to wild areas. Right now, we do not have treatments for naio in the wild or in landscaping. OISC’s experience and anecdotal evidence from others has not found a proven technique that will ensure naio survival after thrips find it.

Protecting wild naio populations is still a priority. Research has begun looking into effective treatment options along with searching for resistance among different varieties of native naio (Myoporum sandwicense) and of our Oʻahu endemic naio species (Myoporum stellatum). Researchers are also considering environmental factors, such as soil conditions and rainfall amounts. Our goal is to find techniques to manage thrips adequately that will protect our wild populations and once again allow naio to be used in landscaping and restoration.

It’s important to keep in mind that naio thrips are detected on Hawaiʻi Island and Oʻahu. Do NOT transport naio between islands to help stop the spread to neighboring islands where it is not established.

Side by side photo of infested and health naio
Albatross nesting under naio at Ka'ena Point.
Naio (Myoporum sandwicense) is a native Hawaiian plant that has been used widely in landscaping. In the wild, naio are important habitat for nesting albatross and shearwaters, Hawai‘i’s endangered yellow-faced bees, and native forest birds like the ‘Amakihi and ‘Elepaio.
Healthy Naio plant. Photo: Forest & Kim Starr
Naio Plant
Healthy Naio plant. Photo: Forest & Kim Starr
Healthy Naio leaves
Healthy Naio leaves. Photo: Forest & Kim Starr
Healthy Naio leavesa nd flowers
Healthy Naio leaves and flowers. Photo: Forest & Kim Starr
Healthy Naio leaves and flowers
Healthy Naio leaves and flowers. Photo: Forest & Kim Starr
curling naio leaves and galls
Severe naio thrips damage…curling leaves and galls. Photo: DLNR
curling naio leaves and galls
Typical naio thrips damage…curling leaves and galls. Photo: DLNR
curling naio leaves and galls
Typical naio thrips damage…curling leaves and galls. Photo: DLNR
Naio Thrips on a leaf
Naio Thrip (Klambothrips myopori) are super tiny! Most times, you will only see the damage they cause. Photo: OISC
Naio Thrips on a leaf
Naio Thrips- tiny, shiny and black. Photo: OISC
Naio Thrip on galled leaf tip
Naio Thrip on galled leaf tip. Photo: OISC

Description:

These tiny insects are native to Tasmania and have caused widespread damage on the popular landscaping Myoporum plants in southern California and in the San Francisco area. They were first detected on Hawaii Island in March of 2009.   Naio thrips can be found on many Myoporum species, but is especially noticeable on our native naio species. The leaf curling and gall formation effects of thrips on naio plants will be noticed before any insects are seen. These thrips are tiny, about 2mm long, and are shin, dark brown.

Damage:

Naio thrips damage includes severe gall-like distortion of the new leaves and terminals. The insects suck out the healthy tissues of new leaves. The stunting of growth at the terminal ends of the plant occurs and leaf curling or folding is common. Eventually new leaves stop forming and the plants will die. In Hawaiʻi, this recent pest can potentially have devastating effects on our native naio trees which are an important component of lowland and coastal dry forest and comprise roughly one half of the plant biomass of the māmane-naio forest ecosystem.

Damage to naio plants from thrips on the left. The galling, or balled-up leaf tips, can kill the plant.

In the naio/mamane forests of Pu’u Wa’a Wa’a Forest Reserve on Hawai’i Island, researchers could not find 10 healthy naio trees a decade after thrips invaded the area. Springer Kaye of the Big Island Invasive Species Committee likened the destructive capacity of the thrips to wildfire. Today, 90% of the wild naio at sites on the Hawai’i Island have died due to the damage caused by thrips.

Distribution:

Naio thrips can be transported to new areas in infested landscaping plants, on people, and locally via the wind. This pest was first noticed on the island of Hawaiʻi in March 2009 and has since spread across the Big Island (map). There is still a chance of preventing this pest from establishing throughout the state. They haven’t been detected on Kauaʻi or Maui County.

How you can help:

  • Do not plant naio. Plant other native or non-invasive plants.
    • You can visit, Plant Pono for healthy landscaping choices.
      • Recommended alternatives are: koaia, a’ali’i,  alahe’e, and ‘ōhi‘a…and for naio papa use ulei.
    • Here is a list on nurseries and store that carry native plants:  Native-Plant-Source-List
    • Honolulu Board of Water Supply has a Oahu Regional Planting Lists for your area based on rainfall.
  • Do not move naio between islands. Currently, only Hawaii Island and Oahu have detections of these thrips.
  • Monitor – Monitor every week for damage to leaves if you choose to keep your naio plants.
  • Infested Plants. Infested plants will exhibit the damaged leaves. It is recommended to do the following:
  1. Remove infected terminals and place in thick contractor grade garbage bags.
  2. Spray material inside the garbage bag in order to kill thrips inside bag  (Conserve or Talstar).
  3. Fell tree or cut trunks if papa.
  4. Spray leaves and branches once on the ground with Conserve or Talstar to kill thrips that have been knocked loose from the activity.
  5. Treat stumps with 20%  Garlon 4 Ultra with 79.5% crop oil and 5% Turf Trax to kill root system.
  6. Cut up into manageable pieces.
  7. Cover with tarp or place in contractor clean up trash bags.
  8. Wait a minimum of 6-8 weeks minimum before removing tarp and bringing material to H-power, or dispose in rubbish, NOT green waste. This will allow plant material to die, eliminating food for remaining thrips or newly hatched thrips.  Check to be sure that you don’t see any live thrips before removing and disposing material.

*When pesticides aren’t used, the same procedure was followed without the use of chemical controls.

Feel free to contact OISC for any questions about infestation or proper removal and/or disposal: oisc@hawaii.edu.

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