Use of a Sustained-Release Chemical Delivery Device in Assessing Effects of Systemic Insecticides

Science Center Objects

Neonicotinoid insecticides the fastest growing insecticide worldwide - and may play a role in the declines of terrestrial and aquatic vertebrate species.

Map of Neonicotinoid insecticide Thiamethoxam use 2011 (USGS-NAQWA)
Map of neonicotinoid insecticide Thiamethoxam use 2011 (USGS-NAWQA)

 

The Science Issue and Relevance: Testing chemical compounds in animals at ecologically realistic levels without the interference by confounding environmental variables is challenging. For instance, in aquatic exposure systems, chemical half-lives can negate biological activity, and in static exposures, ammonia build­up may compromise animal condition. Recent USGS water sampling showed detectable levels of clothianidin and thiamethoxam in the Mississippi River, thus neonicotinoid insecticides (commonly referred to as NEO) may be found in backwater habitat where amphibians are prevalent. Neonicotinoid insecticides are the fastest growing insecticide class globally and have been implicated in bee colony collapse disorder and in declines of numerous terrestrial and aquatic species of vertebrates. The project is setting the stage for wide use of this technology across taxa for expansive studies by USGS and other agencies.

Methodology for Addressing the Issue: In conjunction with a veterinary biotechnology company, a device is being developed that allows for slow release of bioactive compounds of interest. After injecting the device into tissues, the special formulation allows for maintaining steady-state, biologically relevant exposures. In these experiments, the compounds have worldwide agricultural and conservation consequences, and the taxon to be tested is of global concern. Adult leopard frogs will be implanted and biomarkers of response then measured.

Injection in a leopard frog (Lithobates pipiens)
Injection in a leopard frog (Lithobates pipiens)

Future Steps: To apply a sustained release chemical delivery system to a non-mammalian vertebrate for environmentally relevant exposures having physiologically measurable responses, thus demonstrating widespread applicability of the device.