Presenter: Peter Brake, Director of Technical Development, Collier Mosquito Control District, Naples FL
Just a few years ago, use of unmanned aircraft systems (UAS), or drones in mosquito control programs was in its infancy. Today, numerous districts have fully integrated drones into their programs with a host of important safety and economic benefits.
On January 21, as part of Valent BioSciences’ Virtual Floodwater Mosquito Control Summit for the Eastern US, Peter Brake, Director of Technical Development with Florida’s Collier Mosquito Control District (CMCD) provided insights on how drones have transformed the way the district conducts operations.
Located in near the southwestern tip of the state, Collier is the second largest county in Florida. It is surrounded by five neighboring counties and the Gulf of Mexico to the west. Collier spans more than 2300 square miles of land mass, 1500 square miles of which are protected state and federal lands. The county is home to 383,000 full-time residents plus another 80,000 in the winter, meaning tourism is a big part of its industry. In 2018, Southwest Florida hosted more than two million visitors who brought an estimated $1.5 billion to the local economy. Mosquito control is essential.
The district employs eight full-time pilots and seven field technicians. Its conventional aerial fleet consists of three fixed wing Skyvans (used strictly for adulticiding over large areas), plus one Bell 407 and three McDonnell Douglas helicopters used for larvidicing and applications to smaller areas.
The newest member of the aerial team, however, is CMCD’s diverse fleet of drones – each of which performs a unique task within the district’s program. Brake reported CMCD was among the first of the state’s mosquito control districts to make wide use of drone technology and was the first organization in the state of Florida to receive authorization to dispense material from drones.
The Drone Fleet
DJI Mavic Pro Platinum: The district owns three of these drones, which Brake calls their “workhorses.” Used for wetland areas inspection, these drones give the team quick and easy visual access to hard to reach areas while offering improved safety (think spiders and snakes). Operated by a control interface and tablet, these drones allow operators to see what the drone sees, in real time. They also record weather data and images that can be downloaded post-flight. For precision mapping, the Mavic Pro uses Visible Atmospherically Resistant Index (VARI) imaging data, which emphasizes vegetation similar to NDVI (see Phantom 4) and provides significantly higher resolution than Google Earth. Brake said these operations do have some limitations, namely with control tablets overheating in mid-day sun.
Matrice 660P (PV13): The fleet includes one of these application drones, which can carry 13 pounds of material. The PV13 travels at a speed of between eight and 16 mph treating between 0.4 and 1 acre/minute. For liquid (WDG) application, the PV13 applies in a 40-foot swath and can cover about 200 acres on a single tank for an adulticide application. For granular applications, the unit treats in a 30-foot swath with a 1-10 acre per tank capacity and a battery life of 3-4 loads. The drone is especially useful in urban area applications.
Phantom 4 NDVI: This mapping drone is equipped with Normalized Difference Vegetation Index (NDVI), a graphical indicator that can be used to analyze whether or not the target being observed contains live, green vegetation. It measures the level of chlorophyll in the trees and has a red filter that shows transitional areas of dead or dying habitat where mosquitoes often lay their eggs.
SwellPro Splash Drone: This specialized drone is used for observation below the surface of water. It is waterproof and has a camera mounted underneath for inspection of fish and larvae.
Quantum-Systems Trinity: This drone is mainly used for larger surface areas, typically over 100 acres. The flight software is installed on a laptop or PC and uploaded to the aircraft. Brake said that since this drone operates using a different controller, it can fly longer without heat being a factor – making the mapping process more efficient. With a 7.5-foot wingspan, The Quantum Trinity takes off vertically. Once it has reached its assigned altitude, propellers on its wings shut down and another propeller on the tail propels the aircraft forward. Flight times can last as long as 90 minutes. This drone has NDVI and a 20-megapixel camera, with a max range of three to five miles.
To process imaging data captured by the drones for map creation, CMCD uses advanced drone mapping software called DroneDeploy. At a cost of $3600 per year, the software allows technicians to import and export in various file formats and generate an unlimited number of maps.
Brake said CMCD’s drone fleet and systems cost around $86,000. The payback comes in safety, precision, efficiency, and reduced environmental impact.
Safety improvements for urban area application settings are considerable. With helicopter applications, pilots have to fly over and around buildings in highly populated areas, often generating noise and safety complaints. With drones, the team can limit flights to the space directly over the area of treatment, and with far less noise.
The drones’ enhanced imaging capabilities also reduce environmental impact and provide direct cost savings . Originally, CMCD manned aircraft had to rely on Google Earth images, which can be 12 to 18 months out of date. Brake showed an example of a treatment area from 2018 that spanned 326 acres. Re-imaging the site in 2019 using drones, the team was able to reduce the treated area within the block by 87 acres, or 27%. Figuring in an application cost of $125/acre, the savings amounted to $10,875 per mission. With the area receiving three treatments per year, the single-year savings was more than $32,000.
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