Acute Toxicity of Imidacloprid and Fipronil to a Nontarget Aquatic Insect, Simulium vittatum Zetterstedt cytospecies IS-7

Influence of fipronil compounds and rice-cultivation land-use intensity on macroinvertebrate communities in streams of southwestern Louisiana, USA

“…Ali et al (1998) and Stevens et al (1998) reported that chironomid midge larvae were susceptible to fipronil at very low lethal concentrations (LC 50 ¼ 0.42 mg/L and 0.43 mg/L, respectively). Similarly, black fly larvae were determined to be even more susceptible to fipronil (Overmyer et al, 2005) at median concentrations ranging from LC 50 ¼ 0.31e0.18 mg/L much lower than those reported for other macroinvertebrates. Fipronil is highly toxic to estuarine mysid shrimp (LC 50 ¼ 0.14 mg/L), and can affect survival, reproduction, and growth at concentrations as low as 0.005 mg/L (US Environmental Protection Agency, 1996).…”

“…Fipronil degradation Overmyer et al (2005) products were detected with greater frequency than fipronil (the parent compound) in water samples. Fipronil sulfide accounted for the greatest frequency of detection (90%) followed by desulfinylfipronil (88.3%), fipronil sulfone (81.7%), and fipronil (78.3%) (Table 3).…”

“…LC 50 values were complied for fipronil from toxicity tests for chironomid, mosquito, and black fly larvae as described by Ali et al (1998), Stevens et al (1998), andOvermyer et al (2005), and a median LC 50 of 0.42 mg/L for fipronil was used to calculate the PTI for aquatic macroinvertebrates. Because LC 50 data are currently (2006) limited for fipronil degradation products, an estimate of the relative potential toxicity for fipronil sulfide and fipronil sulfone to aquatic macroinvertebrates was based on the USEPA conclusion that fipronil sulfide is 1.9 times more toxic, and fipronil sulfone is 6.6 times more toxic, to freshwater macroinvertebrates than the parent compound (US Environmental Protection Agency, 1996).…”

A useful new insecticide bioassay using first-instar larvae of a net-spinning caddisfly, Cheumatopsyche brevilineata (Trichoptera: Hydropsychidae)

“…The effect of one neonicotinoid (imidacloprid) on aquatic invertebrates has drawn the attention of several researchers. [23][24][25][26][27] Data on the toxicity of this insecticide to arthropods has been available for several years (Fig. 3).…”

Comparison of acute toxicity of two neonicotinoid insecticides, imidacloprid and clothianidin, to five cladoceran species

“…nymphs, crustaceans including ostracods, amphipods, and crayfish, has been reported by many researchers. [41][42][43][44] Since the neonicotinoid chemical class may be safe only to cladocerans, the evaluation of the ecotoxicological risks of the neonicotinoids based on acute toxicity to cladocerans can systematically underestimate the risk of these pesticides to all other aquatic species and communities. Indeed, other scientists have indicated the need for establishing a different risk assessment to this and other classes of systemic insecticides.…”