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Responding to outlier CRB catches (March 2021 Newsletter)

Updated: Apr 19, 2021

This information was originally shared through the Coconut Rhinoceros Beetle (CRB) Response's quarterly newsletter. To sign up for updates on CRB, add your name to the form at the bottom of this page.

This heat map shows where our traps have caught CRB in the past six months. Our highest-catch areas are represented by larger circles and include Pearl City Peninsula, Waipio Peninsula, and Iroquois Point. Emerging populations in Mililani and Kunia are represented by smaller circles. New single beetle detections in Pupukea, Waimanalo, and Kaneohe are believed to be human-vectored. Green waste should not be moved from or staged overnight in hot zones or emerging areas.

CRB Field Updates:

CRB larvae after vacuum steam treatment

Our field leads have been busy optimizing protocol for the vacuum steam unit (VSU). Mulch is loaded into the VSU and the unit heats the material to a temperature fatal to CRB (right). We hope to treat all potential breeding material from our highest catch areas once the protocol is established and staff is trained.

HISAM 2021:

February was Hawaii Invasive Species Awareness Month #HISAM2021! Partner agencies working on invasive species across the state came together for a month of interesting webinars, an invasive species tournament, virtual field trips, and more! Our outreach team presented "The Unique Case of Coconut Rhinoceros Beetle in Hawaii" and created a fun Instagram filter to help determine "Which CRB are you?" Watch our HISAM presentation here.

Canine team update:

Canine handler Vanessa has moved on from her position to pursue a Master's degree in Environmental Law. Our new handler Marlee will begin in March and we're excited to welcome her to the team.

Data team update:

During Q1 of 2021, our crew welcomed three new data team members. They've been working on transitioning field data collection technologies into more efficient systems.

Outlier Catches

Looking at our most recent trap detections, it is apparent that human vectored spread continues to advance the CRB population into uninfested areas. So what happens when a new detection occurs outside of our buffer zone? Our protocol to quickly respond to new catches involves several aspects of our program.

Traps: One of the first things we'll do in a new catch area is to deploy more traps. We service over 3,100 traps across Oʻahu. These traps are our primary mode of detection and have proved to be an invaluable tool in understanding CRB populations. The island is divided into a square mile grid and traps are placed at regular intervals. In a high-catch area, we may have up to 64 traps per square mile, compared to one trap per square mile in areas with no previous detections. The reason for deploying more traps is to help locate a potential breeding site. Because traps in our low-catch areas are generally spread out, we hope that the increase in traps will allow us to identify a specific area to search for breeding sites.

Tree Survey: Another early step in a new detection area is performing a tree damage survey. Our field crew goes out to the area, makes note of all the potential CRB food sources (coconut, royal, date, and fan palm), and identifies CRB damage. It is unknown how often an adult CRB feeds, but understanding palm growth can help us estimate when a feeding event took place. CRB feed on the inner spear or "heart" of the palm, and damage can sometimes take months to appear. If tree damage is spotted, CRB may have been feeding in the area before they were detected by our traps.

Contact Tracing: Contact tracing is regularly used to track the movement of COVID-19,

but similar strategies can be used to track invasive species. Starting with the areas closest to the detection, our outreach team contacts residents and businesses to share information about CRB, locate potential breeding sites and seek information about how the beetle may have gotten to the new area. Once we identify that pathway we can prevent future transport of beetles by that mechanism.

Breeding Site Survey: With the information gathered through the additional traps, tree survey, and contact tracing we're then able to conduct a breeding site survey. Identifying and mitigating breeding sites continues to be one of the most effective ways to reduce CRB populations. Our canines are trained to smell CRB larvae and have helped identify breeding sites. If a breeding site is found, our team is ready to work with the landowner to treat the pile and mitigate its risk of spread.

Outlier catches do not always coincide with population spread. Beetles caught in Waikiki, Diamond Head, and Waimanalo have not resulted in regular trap catches that would indicate a breeding population. While our new detections in Pupukea and Kaneohe are alarming, our protocol to respond to outlier catches is designed to prevent the establishment of breeding sites. You can help prevent outlier catches by refusing to bring mulch in or out of CRB hot zones and reporting CRB and tree damage to the Response.


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