In the summer of 2019, Ada County Weed, Pest and Mosquito Abatement District in Idaho evaluated MetaLarv S-PT at low and mid-label rates at 2.5 and 3.75lbs/acre. Plot 1, which was 14.8 acres of flood-irrigated pasture was treated with 2.5lbs/acre on 7/22/2019 and was flooded during the treatment. Throughout the trial, the water temperature at Plot 1 ranged from 62-82.4°F and MetaLarv S-PT provided 100% emergence inhibition (%EI) over 6 weeks of control throughout two flood cycles.

Data provided by Desireé Keeney, Deputy Director, Ada County Noxious Weed, Pest and Mosquito Abatement

Plot 1 to test floodwater mosquitoes against MetaLarv

Plot 3, which was 11.5 acres of flood-irrigated pasture was treated with MetaLarv S-PT at 3.75lbs/acre on 7/22/2019. At the time of application, the pasture was dry indicating a pre-flood treatment. Throughout the 6 weeks of monitoring, the water temperature ranged from 69-81°F. The field team collected pupae and monitored larval populations once a week for 6 weeks. On week 4, 75% emergence inhibition was observed indicating control for 4 weeks in a pre-flood treatment.

plot 3 floodwater mosquitoes against MetaLarv

MetaLarv S-PT is an (S)-methoprene product with performance against floodwater mosquitoes for up to 42 days. (S)-methoprene is an insect growth regulator that mimics the juvenile hormone found in high levels in early instar larvae. This juvenile hormone is necessary for each instar to be able to molt. However, as the larvae get bigger, they need less hormone. (S)-methoprene mimics juvenile hormones that effect fourth instar larvae and pupae and prevent them from emerging as flying, biting adults. MetaLarv S-PT can be applied to a habitat up to 28 days before a flood event occurs, providing timing and application flexibility for the district. It can be used at lower rates of 2.5-5 pounds per acre, which allows the district to save money.

MetaLarv S-PT, a spherical pellet formulation, uses Triple Release Technology™, which provides three different releases of (S)-methoprene. The reason for this proprietary technology is so that the product can be used in habitats that flood, dry-down and reflood. The first release provides a flash of (S)-methoprene for immediate control of mosquitoes. The second release takes place as the floodwaters rise, which provides control throughout the entire flood event. The third and final release occurs after there has been a dry-down and re-flood of the habitat. The Triple Release Technology™ uses a non-charcoal UV protectant that eliminates much of the dust associated with other (S)-methoprene based products. This formulation reduces the exposure to dust for the operator and leaves equipment cleaner.

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