Acute toxicity of 6 neonicotinoid insecticides to freshwater invertebrates

Abstract

Neonicotinoids are a group of insecticides commonly used in agriculture. Due to their high water solubility, neonicotinoids can be transported to surface waters and have the potential to be toxic to aquatic life. The present study assessed and compared the acute (48- or 96-h) toxicity of 6 neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam) to 21 laboratory-cultured and field-collected aquatic invertebrates spanning 10 aquatic arthropod orders. Test conditions mimicked species' habitat, with lentic taxa exposed under static conditions, and lotic taxa exposed under recirculating systems. Median lethal concentrations (LC50s) and median effect concentrations (EC50s; immobility) were calculated and used to construct separate lethal- and immobilization-derived species sensitivity distributions for each neonicotinoid, from which 5th percentile hazard concentrations (HC5s) were calculated. The results showed that the most sensitive invertebrates were insects from the orders Ephemeroptera (Neocloeon triangulifer) and Diptera (Chironomus dilutus), whereas cladocerans (Daphnia magna, Ceriodaphnia dubia) were the least sensitive. The HC5s were compared with neonicotinoid environmental concentrations from Ontario (Canada) monitoring studies. For all neonicotinoids except imidacloprid, the resulting hazard quotients indicated little to no hazard in terms of acute toxicity to aquatic communities in Ontario freshwater streams. For the neonicotinoid imidacloprid, a moderate hazard was found when only invertebrate immobilization, and not lethality, data were considered. Environ Toxicol Chem 2018;37:1430-1445. © 2018 SETAC.

Assessment of Sublethal Effects of Neonicotinoid Insecticides on the Life‐History Traits of 2 Frog Species

“…For example, Pochini and Hoverman () found that prior Ranavirus infection increased pesticide toxicity in wood frogs, specifically reducing the lethal concentration of thiamethoxam by 55% (from ~2.2 to ~1 mg/L). Finally, neonicotinoids could have indirect effects on amphibians by reducing prey abundance because insects have been found to be directly affected at much lower concentrations and well within the concentration range tested in the present study (Bartlett et al ; Raby et al ); this is similar to concerns for aerial insectivores, such as tree swallows (Gibbons et al ). Although the effects of individual neonicotinoids in controlled laboratory environments have provided important insights on their aquatic toxicology, interactive effects between chemical contamination and additional stressors such as predation or parasitism could provide a more comprehensive understanding of the risks of neonicotinoids in whole ecosystems (Marcogliese and Pietrock ).…”

Chronic toxicity of 6 neonicotinoid insecticides to Chironomus dilutus and Neocloeon triangulifer

“…Dinotefuran and thiamethoxam showed the least potency, with EC50s for emergence of >8 µg L −1 for C. dilutus and >2 µg L −1 for N. triangulifer . This ranking follows both our assessment of chronic toxicity for the cladoceran Ceriodaphnia dubia (Raby et al, unpublished manuscript), acute toxicity for aquatic invertebrates (Raby et al ), and the ranking expressed in other studies. For example, Morrissey et al () summarized acute toxicity to aquatic insects for 6 neonicotinoids, and ranked thiacloprid and clothianidin highest, and dinotefuran and thiamethoxam lowest.…”

“…Neonicotinoids are designed to bind to the nicotinic acetylcholine receptors found in insect pests, causing a constant nerve stimulation that leads to changes in behavior and eventually death (Matsuda et al ; Morrissey et al ). Insects have been found to be among the most sensitive to neonicotinoids, and crustaceans the least (Morrissey et al ; Raby et al ). Previous work in our laboratory found that Chironomus dilutus (Insecta: Diptera) and Neocloeon triangulifer (Insecta: Ephemeroptera) were the most sensitive species in acute water‐only tests with 6 neonicotinoids.…”

“…Previous work in our laboratory found that Chironomus dilutus (Insecta: Diptera) and Neocloeon triangulifer (Insecta: Ephemeroptera) were the most sensitive species in acute water‐only tests with 6 neonicotinoids. The 96‐h median lethal concentrations (LC50s) for C. dilutus ranged from 1.6 µg L −1 for thiacloprid to 61.9 µg L −1 for thiamethoxam (Raby et al ). Similar 96‐h LC50 estimates exist in the literature, and range from 1.85 µg L −1 for clothianidin to 55.34 µg L −1 for thiamethoxam (Stoughton et al ; LeBlanc et al ; de Perre et al ; Maloney et al ).…”

“…Similar 96‐h LC50 estimates exist in the literature, and range from 1.85 µg L −1 for clothianidin to 55.34 µg L −1 for thiamethoxam (Stoughton et al ; LeBlanc et al ; de Perre et al ; Maloney et al ). Neocloeon triangulifer was more sensitive than C. dilutus ; 96‐h LC50s for all 6 neonicotinoids studied were <10 µg L −1 (Raby et al ). Compared with acute toxicity, less is known about the chronic toxicity of neonicotinoids to these sensitive species.…”