7/6- Resistance Testing

 This week, we were exploring the potential development of Natular resistance in mosquito larvae. This was in response to a suspicious number of treatments giving way to larval activity before their listed expiration date. We have been treating the vast majority of these sites with Natular products, both in briquette and granular form. The newfound resistance to these products is alarming, considering the frequency with which we employ them. To test resistance, we captured hundreds of 2nd-stage larvae. These larvae were then sorted into cups with increasing concentrations of Natular G30. The larvae were "fed" twice daily. In total, the experiment ran for three days. The findings were concerning; ~20-30% of larvae survived all stages of treatment, with an additional ~10% surviving until the last treatment. This displays a clear resistance to Natular products, at least with larvae located in the Animas district. 

The actions to be taken following this experiment are at the moment unclear, but wholly necessary. There has been talk of switching to BTI (Bacillus thuringiensis) as a means of larvicide; however, the district has employed BTI in the past and received disappointing results. I hope to find out what our course of action will be within the next week, as this is a rather startling new development in this year's mosquito abatement season.