Operational Basin Larvicide Evaluations in Northern Cook County, Illinois During 2019 and 2020

ABSTRACT Over the course of 2019 and 2020, 7 larvicide formulations for use in catch basins were evaluated using a standardized pass/fail protocol. A comparison between 1- and 2-pouch doses of VectoLex® water-soluble pouches (WSP; 10 g per pouch) and 20 g of VectoLex FG (loose granules) suggests that the WSP formulation may have a shorter duration than the FG formulation. Results also suggest that 20 g doses of each of 2 larvicides, Duplex™-G and Sumilarv® 0.5G, may have a minimum effective duration in basins for approximately 40 days. A 20 g dose of Altosid® XR-G and a single briquet Altosid XR each had an observed minimum effective duration of 20 days. Sustain MBG had an observed duration of only 7 wk posttreatment. These observations provide evidence that, in some locations, 20 g granular applications may have a longer effective duration than a single briquet. This work highlights the utility of applying a standardized protocol for routine quality control assessments of the thousands of catch basin larvicide applications performed seasonally by mosquito abatement districts.

Modelling of methoprene concentration at storm sewer outfall

The objective of this report is to compare the predicted concentration of methoprene, a larvicide used in the City of Toronto to control the widespread of West Nile Virus by suppressing mosquito growth, at storm sewer outfall during a typical year rainfalls (1980 rainfalls) with the Interim Provincial Water Quality Objectives (IPWQO). The methoprene that is under investigation in this report is in form of ingot. Extending from an existing spreadsheet-based model that simulates the methoprene concentration within two monitored catch basins in the Newtonbrook sewershed of North York, methoprene concentration at the sewer outfall during the 1980 rainfalls is predicted by linear projection upon calibration of the model with the methoprene mass at the outfall measured in year 2005. Results show that predicted methoprene concentration at outfall exceeds the IPWQO in six days out of the one-hundred-day period. It is recommended that to better mimic the actual situation, traveling time effect and sensitivity analysis on catch basin sump volume be included in future study.

Modelling of methoprene concentration at storm sewer outfall

The objective of this report is to compare the predicted concentration of methoprene, a larvicide used in the City of Toronto to control the widespread of West Nile Virus by suppressing mosquito growth, at storm sewer outfall during a typical year rainfalls (1980 rainfalls) with the Interim Provincial Water Quality Objectives (IPWQO). The methoprene that is under investigation in this report is in form of ingot. Extending from an existing spreadsheet-based model that simulates the methoprene concentration within two monitored catch basins in the Newtonbrook sewershed of North York, methoprene concentration at the sewer outfall during the 1980 rainfalls is predicted by linear projection upon calibration of the model with the methoprene mass at the outfall measured in year 2005. Results show that predicted methoprene concentration at outfall exceeds the IPWQO in six days out of the one-hundred-day period. It is recommended that to better mimic the actual situation, traveling time effect and sensitivity analysis on catch basin sump volume be included in future study.

Modelling the fate of a larviciding chemical, methoprene, at drainage systems

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

Modelling the fate of a larviciding chemical, methoprene, at drainage systems

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

The Fate and Transport Of Methoprene in an Urban West Nile Virus Mosquito Control Program

The recent occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. The City of Toronto has focused its larviciding program on storm water catch basins as they are concentrated breeding grounds of the mosquito (Culex pipiens) most likely to carry West Nile virus. The City of Toronto undertook a larviciding program to control mosquitoes during the summer months of 2003. The larvicide approved for mosquito control in Canada is methoprene, commercially known as Altosid, in pellet formulation. In order to determine the fate of the larvidice methoprene, the researcher, in conjunction with current studies at Ryerson University, the City of Toronto and the Ontario Ministry of the Environment, have undertaken a water quality monitoring study within the Toronto area. Three study catch basins in the Newtonbrook sewershed in Toronto, Ontario, were dosed with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control does of 0.7g. Water from each catch basin was sampled daily and analyzed for methoprene concentration, and mosquito larvae presence was observed. Precipitation, as well as the chemical composition of each of the catch basins was also monitored. A catch basin model in the laboratory was also dosed with methoprene pellets and sampled daily to observe methoprene concentration over time. The fate of methoprene in the urban environment is of interest, to ensure that the larviciding program is not conpromising human and environmental safety. It was found that rainfall flushes methoprene from the catch basins into the storm sewer outfall. The storm sewer outfall did not release methoprene at detrimental concentrations during the sampling period. Many factors such as physical dissolution, chemical degradation and catch basin water volume, affect the concentration of methoprene in a catch basin. In order to monitor the impacts of larviciding programs, comprehensive water quality monitoring and mosquito control efficacy should continue.

The Fate and Transport Of Methoprene in an Urban West Nile Virus Mosquito Control Program

The recent occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. The City of Toronto has focused its larviciding program on storm water catch basins as they are concentrated breeding grounds of the mosquito (Culex pipiens) most likely to carry West Nile virus. The City of Toronto undertook a larviciding program to control mosquitoes during the summer months of 2003. The larvicide approved for mosquito control in Canada is methoprene, commercially known as Altosid, in pellet formulation. In order to determine the fate of the larvidice methoprene, the researcher, in conjunction with current studies at Ryerson University, the City of Toronto and the Ontario Ministry of the Environment, have undertaken a water quality monitoring study within the Toronto area. Three study catch basins in the Newtonbrook sewershed in Toronto, Ontario, were dosed with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control does of 0.7g. Water from each catch basin was sampled daily and analyzed for methoprene concentration, and mosquito larvae presence was observed. Precipitation, as well as the chemical composition of each of the catch basins was also monitored. A catch basin model in the laboratory was also dosed with methoprene pellets and sampled daily to observe methoprene concentration over time. The fate of methoprene in the urban environment is of interest, to ensure that the larviciding program is not conpromising human and environmental safety. It was found that rainfall flushes methoprene from the catch basins into the storm sewer outfall. The storm sewer outfall did not release methoprene at detrimental concentrations during the sampling period. Many factors such as physical dissolution, chemical degradation and catch basin water volume, affect the concentration of methoprene in a catch basin. In order to monitor the impacts of larviciding programs, comprehensive water quality monitoring and mosquito control efficacy should continue.

Reliability Assessment in Wireless Apparatus Using LoRa and Sigfox in Catch Basin

The importance of preventing damage from pluvial flooding has been increasing under global climate change. The discovery of premonitory symptoms of pluvial flooding enables effective evacuation and inundation prevention activities. However, apparatuses that automatically detect this in real time are not widespread. There are difficulties in the cost of installing them and the agreements made by the parties concerned, especially in cities. To solve this problem, we devised an apparatus to be installed inside a catch basin that detects its water level. The water level in the catch basin may indicate a sign of pluvial flooding, and the number of people involved in operating the catch basin is smaller than that of facilities on the ground. In order to reduce the cost of installation and operation, we adopted Low Power Wide Area (LPWA), which is a communication method that enables wireless transmission of detected information over long distances for a long time using batteries. So far, for catch basins, a wireless transmission experiment was conducted using LoRa, which is part of LPWA. However, Sigfox, which uses the same frequency as LoRa but has a different wireless system, has not been verified. In this study, the reliability of wireless communication was assessed by apparatuses using LoRa and Sigfox side by side in each catch basin in two places in a densely populated city. The number of experiment days and transmissions differed depending on the apparatus, with the number of days ranging from 97–151 and the number of transmissions from 2328–3748. The reliability in the experiment ranged from 99.97–99.53%. The experimental results showed that wireless transmission was possible with high reliability using either the LoRa or Sigfox system from inside these catch basins. This study expands the options for communication infrastructure that can be used for apparatuses that detect premonitory symptoms of pluvial flooding. This will enable a reduction in installation costs and will expand the range of areas of potential installation.

INCREASED WATER HARDNESS IN CATCH BASINS TREATED WITH SPINOSAD (NATULAR XRT) EXTENDED RELEASE TABLETS

In response to apparent lack of efficacy of spinosad treatments of storm drain catch basins in Marathon, Florida, we investigated water quality parameters where drains had been treated with Natular® XRT extended release tablets. An analysis of water samples from these sites revealed that alkalinity and water hardness differed significantly between treated and untreated drains. However, when tested in a semi-field environment protected from runoff, differences in alkalinity were not associated with spinosad treatment, whereas water hardness increased over time in replicates treated with Natular XRT. Water quality may be a reason for poor larval control rather than product failure or resistance. Future work will investigate whether changes in water hardness associated with spinosad treatment may impact the efficacy of this larvicide at reducing adult emergence in field environments.