Navigating the Impact of Natular G on Non-Target Organisms: A Study in Minnesota’s Vernal Pools and Cattail Marshes
In regions with extensive wetlands, such as those monitored by the Metropolitan Mosquito Control District (MMCD), mosquitoes pose ongoing challenges as disease vectors and as nuisance. This is where integrated mosquito management strategies come into play to mitigate mosquito population levels and survey for disease presence. Of course, while mosquito control products undergo rigorous testing and regulation while obtaining EPA registration, supplemental field studies often are conducted to demonstrate the efficacy and impacts of products.
In this case, the MMCD conducted a comprehensive field study to examine Natular G’s – and its active ingredient, Qalcova-brand spinosad – ability to control mosquitoes while still minimizing harm to non-target organisms. These two studies were conducted via treatments in both vernal pools and cattail marshes, presenting a detailed analysis of Natular G’s efficacy and non-target impact.
For the full study, visit MMCD’s site here:
As MMCD began adopting the use of the Natular formulation line as part of its larviciding and resistance management strategy, largely due to its EPA classification as a reduced risk pesticide. Still concerns were raised by MMCD’s Technical Advisory Board (TAB) regarding the use of spinosad, the active ingredient in Natular G, in spring vernal pools, where in addition to mosquito larvae, various invertebrates critical to the local ecosystem lived. In response, a TAB subgroup was formed in 2012 and 2013 to conduct studies specifically to test Natular G more specifically on these native invertebrates.
Study sites were selected based on the historic breeding areas of Aedes mosquitoes in the spring, with vernal pools being studied in 2014 and supplemental cattail marshes being studied in 2015. Testing conducted by MMCD used a double-blind study design to minimize biases.
This research provides insights into Natular G’s applications in vernal pools and cattail marshes, highlighting its effectiveness and ecological implications for integrated mosquito management strategies.
For the full study:
In the vernal wetland study, ten sites were selected based on their historical productivity of spring hatching Aedes mosquitoes. MMCD employed a double-blind method, with half of the vernal pool sites receiving Natular G granules and the other half treated with blank granules to eliminate bias and ensure the validity of the results.
MMCD’s team collected samples along randomly selected transects at the water surface and near the wetland bottom both three days prior to the treatment applications as well as seven and fourteen days after treating the sites with the Natular G granules. Samples were collected at the water’s surface and near the wetland bottom. In the lab, MMCD then processed collected samples and identified the number of and species of selected invertebrates present in each.
Overall, it was found that there was no significant impact on fairy shrimp, fingernail clams, and freshwater snails present in the vernal pools. In addition, Natular G achieved a reduction in various spring Aedes species ranging from 53% to 84%.
Unfortunately, one of the invertebrates, amphipods, that MMCD’s TAB subgroup was hoping to study was not present in the vernal pools at the time of the study.
In 2014, the absence of amphipods in the vernal pool sites prompted a subsequent study in 2015 to focus on cattail marshes where amphipods were found. Similarly to the vernal pool study, MMCD used a double-blind methodology, with five cattail marshes sites being treated with Natular G and five only receiving blank granules. Invertebrates and emerging adult mosquitoes from each marsh were collected at similar intervals before and after these treatments using basal area pyramidal emergence traps and then analyzed by MMCD in their labs.
Despite minimal control of Cq. perturbans (cattail mosquito) by Natular G in cattail marshes, there were no clear adverse effects on amphipods or the isopods which were also collected in the samples.
For the full study, visit MMCD’s site here:
The results of both studies underscored the efficacy of Natular in controlling spring Aedes mosquitoes, while also highlighting its minimal impact on non-target organisms. With OMRI Listed® formulations, US EPA Reduced Risk larvicide offering a unique mode of action, the Natular portfolio sets the standard for efficacy, environmental stewardship, and resistance management. Its active ingredient, spinosad, is of low acute and chronic toxicity to a wide range of non-target species and degrades rapidly in both soil and water.
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