Incipient Invasive Species Control and Outreach in the Ko’olau
December 1, 2020 – December 31, 2021
2021 Final Report to:
HAWAII INVASIVE SPECIES COUNCIL
Prepared By:
KOʻOLAU MOUNTAINS WATERSHED PARTNERSHIPINTRODUCTION
The Ko‘olau Mountains Watershed Partnership (KMWP) is a project of the Pacific Cooperative
Studies Unit (PCSU) with the University of Hawai‘i (UH) that addresses island-wide
conservation issues by working with public and private conservation groups, state, municipal andfederal agencies, and private landowners. KMWP’s mission is to perpetuate the water resourcesof Oʻahu by protecting and enhancing the forests of the Ko'olau and its invaluable nativeecosystems. The Ko‘olau Mountain Range has one of the highest densities of rare species in theworld. The area provides habitat for dozens of endangered species, many of which are endemic
to the range and found nowhere else in the world.
Poamoho is an area in the northern Koʻolau Range that provides habitat for 11 animal species
and 18 plant species that are vulnerable to, or have a high risk of, extinction. The Oʻahu Army
Natural Resources Program discovered the highly invasive cane ti (Tibouchina herbacea) in thePoamoho region in 2008. Since 2016, KMWP has worked to conduct control, monitoring, anddelimiting surveys for cane ti along Paukauila stream, which runs through the Poamoho Natural
Area Reserve across Kamehameha Schools lands.
The Waiawa Management Unit (MU) is an approximately 1,500-acre area and is currently being
fenced to prevent ungulate damage. Waiawa is dominated by native wet forest and is categorized
as a priority 1 watershed by KMWP based on rainwater data from UH and usage assessment bythe Honolulu Board of Water Supply. This watershed feeds into the Pearl Harbor Aquifer, whereOʻahu gets the majority of its drinking water. Albizia (Falcataria moluccana) is an extremely
fast-growing tree species and was planted as part of early reforestation efforts in 1917. Since thattime it has come to dominate significant portions of urban/forest interfaces, riparian zones,
agricultural land, critical infrastructure corridors, and low- to medium-elevation forests onOʻahu. Since 2018, KMWP has been working to achieve regional eradication of all albizia acrossthe MU. Although target numbers are relatively low, the effort required to control individual
trees is high. Access to target trees requires helicopter flights into the area and up to a full day of
hiking to traverse across densely forested, steep terrain. Though efforts to control these incipient
trees have been relatively substantial, they are insignificant when compared to the future costs ofattempting to control robust and dominant albizia populations.
For the past six years, KMWP has been utilizing the scale insect Tectococcus ovatus as a
biocontrol to reduce the impact of the invasive myrtle Psidium cattleianum, or strawberry guava,
on native forests. Tectococcus shares a native range in South America with strawberry guava andhinders its host plant’s growth through the formation of leaf galls. In years leading up to thisproject, with the assistance of source material from the Hawaiʻi Division of Forestry andWildlife, KMWP outplanted host plants inoculated with Tectococcus across 31 sites spreadthroughout the Koʻolau range. As the methods for effective utilization of this biocontrol werestill being developed during this period, the success of these introductions was mixed, with somelocations showing significant spread of Tectococcus onto surrounding stands of guava, andothers unable to establish lasting populations at all. Only 11 of these 31 sites remain as effective
centers of Tectococcus populations. This project sought to utilize new techniques andinformation from the US Forest Service, Hawaiʻi Division of Forestry and Wildlife, and theHawaiʻi Department of Land and Natural Resources, in addition to researching and developing
novel methods in-house, to increase Tectococcus’ impact on Oʻahu.
GOALS
The goals of this project were to:●●●●Reduce the impacts of invasive species on priority watersheds
Protect water quality and supply for communities and agriculture on Oʻahu
Improve habitat quality for at-risk species
Increase public awareness on O‘ahu with regards to general species information and thedamage that can be caused by albizia trees

EXPECTED OUTCOMES
1. Incipient Cane Ti Control● Two surveys per section per year completed for the upper 7 sections of Paukauila Stream.
2. Incipient Albizia Control● Two days of on the ground control and surveys completed. Depending on ability tocombine efforts and leverage staff and helicopter time with other projects in the Waiawa
MU, total regional eradication from the area is expected by the end of the project period.
3. Albizia Outreach● Continued Participation it the Statewide Albizia Working Group● Creation of O’ahu-specific albizia outreach materials● One presentation to a community group on albizia impacts and control methods

● One volunteer event with a community-based control team
4. Tectococcus ovatus Biocontrol Deployment● One map created to determine gaps in biocontrol agent establishment sites● T. ovatus established at 5 new sites● Development of initial sUAS methods for T. ovatus agent delivery
Summary
1. Incipient Cane Ti Control
Two sets of surveys of the upper 7 sections of Paukauila Stream were conducted roughly six
months apart, covering a total of 46.1 acres and controlling 87 cane ti plants (figure 1). Thesesurveys were supplemented by funding from the Watershed Partnership Protection Grant(WPPG) to allow for two more sets of surveys of the same 7 sections, providing for quarterlycontrol operations, as well as two more partial sets of surveys for the lower 7 sections of thestream. These surveys along the lower sections were curtailed to divert funding to allow forground control of a windward core, discovered in 2020, outside of the stream. Management of
this newer population, which has resulted in a steady decline in plant numbers, will continue
with additional WPPG funds.
2. Incipient Albizia Control
In accordance with the expected objectives, resources from other projects in the Waiawa MU
were leveraged to allow for a total of 4 days of albizia control in the area, totalling 29.7 acres ofmanagement and the removal of 37 trees (figure 2). All identified trees in the MU were removed,
prompting an expansion of the MU onto the US Fish and Wildlife forest reserve covering themajority of the northernmost valley that contributes to the Waiawa watershed. Removal of thetrees remaining in this area will achieve full regional eradication of the species from the upper
elevations Waiawa. Future monitoring will need to be conducted in order to identify incidents ofre-establishment, which can eventually be expected due to the possibility of small, immature
trees hiding under dense canopy cover, as well as populations at low elevations along windward
slopes east of Waiawa dispersing seed back into the MU.
3. Albizia Outreach
The Rapid Albizia Death (RAD) hui was established as a way to empower lay community
members to manage albizia populations on their own, following instruction and demonstrations
from KMWP staff. A flier, adapted from educational materials developed by James Leary, J.B.
Friday, Springer Kaye, and Flint Hughes, was distributed to community leaders to inform themof established, effective management techniques (figures 3 and 4). Regular involvement with theMalama Manoa community board, where multiple presentations on the RAD hui have been
conducted, and two volunteer events with local hui members have resulted in the control of 12trees and identification of many more across 2,650 meters of stream running through residentialManoa. KMWP management continues to participate in the Statewide Albizia Working Group.

Figure 1. Map of cane ti removal efforts

Figure 2. Map of albizia removal efforts.

Figure 3. Rapid Albizia Death hui Albizia treatment flier page 1.

Figure 4. Rapid Albizia Death hui Albizia treatment flier page 2.

Figure 5. Community removal of Albizia in Manoa valley.

Figure 6. Ring-barked Albizia tree - an herbicide-free treatment method.

4. Tectococcus ovatus Biocontrol Deployment
Utilizing guava stands inoculated with Tectococcus ovatus through efforts in years prior as stock
for fresh material for new introductions, KMWP was able to establish 21 new host sites acrossthe Ko’olau in 2021 (figure 7). Existing site data, compiled from various conservationorganizations, hosted, and managed online by James A. Cullison at the Hawaiʻi Department ofLand and Natural Resources, was analyzed to determine the location of gaps in the presence ofTectococcus and prioritize their closure based on existing infrastructure and other KMWP
objectives. Geospatial data was recorded for each site and added to the online database forreference by other agencies. Emphasis was placed on higher elevation locations, mostly foundupwind of other guava populations within the context of normal trade wind patterns, to try andmaximize passive spread by wind. In order to improve the likelihood of establishment, hostleaves inoculated with the scale were spread as new leaves were flushing in the canopies oftarget sites.
Methods of introduction ranged from extremely opportunistic to planned out well in advance,
utilizing specialized equipment. They included taping gall-bearing leaves to plants, tying themwith twine, attaching a string of leaves to sticks fired out of a slingshot (Pocket Shot CircularSlingshot brand), and dropping them from the air with the use of a small unmanned aircraft
system (sUAS / drone) equipped with a remote-drop hook. Results of each method will need tobe monitored to check for long-term success, but initial observations of spread look promising.
Use of the drone for remote deployment was promising but wasn’t without hardware issues. ADJI Mavic 2 Pro was equipped with a Drone-Sky-Hook brand Release & Drop remote hook tocarry and release cargo (figure 8). The device is a 3D printed chassis with battery, servo-motor
powered rotating hook, and a light sensor. It is quick to attach and remove, and only weighs 49g,making it an easy addition to a field operation. As with many commercially available remote
hooks, it functions by monitoring LED lights used by the drone for visual identification during
flight. Switching the lights on and off via the drone’s remote control signals the hook to rotate.
This releases the cargo, though in some instances the hook failed to rotate for undeterminedreasons. Thin, biodegradable twine, roughly a foot long, was used to tie a string of inoculated
leaves to the hook with a loop (figure 9). Downwards-facing object-avoidance sensors triggered
alerts due to this, which caused the unit to initiate landing procedures when attempting to drop
altitude without forward velocity. However, longer lines under such light loads, used to avoid
tripping the sensors, carried greater risk of engaging with propellers, especially in windy
conditions. To remain within FAA part 107 regulations, drones can’t fly past visual line of sight,
unassisted by tools such as binoculars, but the Mavic Pro 2 is capable of flying over a mile fromits operator. The sUAS Release & Drop can easily disperse material at a distance, allowing for
dispersal to occur simultaneously with other field operations, significantly reducing the cost andeffort of distribution expansion. The effectiveness of this initial method will continue to bemonitored.

Figure 7. Map of locations KMWP released T. ovatus this year.

Figure 8. Drone-Sky-Hook brand Release & Drop remote hook mounted to underside of a DJI
model Mavic 2 sUAS. A payload located under the drone is attached to the hook, exiting thebottom edge of the frame of the photo, while the cable to the light sensor exits the frame to theleft.

Figure 9. Drone with Tectococcus ovatus payload attached. With this configuration leaves have alower chance of triggering downward-facing object avoidance sensors, but run the risk of hitting
propellers. Care must be taken to not fly too fast or in windy conditions.