Small-Scale Trials Suggest Increasing Applications of NatularTM XRT and NatularTM T30 Larvicide Tablets May Not Improve Mosquito Reduction in Some Catch Basins. Journal Article


Authors: Harbison, Justin E.; Henry, Marlon; Corcoran, Peter C.; Zazra, Dave; Xamplas, Christopher
Article Title: Small-Scale Trials Suggest Increasing Applications of NatularTM XRT and NatularTM T30 Larvicide Tablets May Not Improve Mosquito Reduction in Some Catch Basins.
Abstract: Stormwater catch basins are commonly treated with larvicides by mosquito control agencies to reduce local populations of mosquito species capable of transmitting West Nile virus. Recent evidence suggests that extended-release larvicides formulated to last up to 180 days in catch basins may not be effective in some basins due to chronic flushing, rapid dissolution, or burying of treatment in sump debris. To investigate if increasing the number of applications could improve effectiveness, a small study was performed over 13 weeks in 2015 to evaluate two extended-release larvicides (NatularTM XRT 180-day tablets and NatularTM T30 30-day tablets) and a larvicide oil (CocoBearTM). Over the course of 13 weeks, three groups of eight basins were monitored for mosquitoes, each group receiving NatularTM XRT, NatularTM T30, or CocoBearTM larvicides. All basins received a single application at the beginning of the study period. Once mosquitoes in a basin surpassed the treatment threshold during weekly monitoring, an additional application of the associated larvicide was given to that basin. The number of applications during the study period ranged from 1 to 10 for CocoBearTM basins, 1 to 7 forT30 basins, and 2 to 8 for XRT basins. Overall, the average number of applications and the cost of larvicide per basin were 4.4 applications at $0.66 per CocoBearTM basin, 4.4 applications at $6.26 per T30 basin, and 4 applications at $16.56 per XRT basin. Basins treated with XRT and T30 needed reapplications more often than expected, yet were no more effective than CocoBearTM, suggesting that increasing the frequency of application of these larvicide formulations may not provide increased mosquito reduction in some basins.
Journal Title: Environmental health insights
ISSN: 1178-6302; 1178-6302
Publisher: Unknown  
Date Published: 2016