Acute toxicity and related metabolism of pyridalyl in Chironomus yoshimatsui and Hyalella azteca

Abstract

IntroductionPyridalyl (I) [2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-(trifluoromethyl)-2-pyridyloxy]propyl ether] is a new insecticide controlling Lepidoptera and Thysanoptera on cotton, fruits and vegetables. [1][2][3] Aquatic invertebrates are more susceptible to I than fish and algae, based on standard ecotoxicological data: common carp (Cyprinus carpio) 96-hr LC 50 , Ͼ10 mg/l; Daphnia magna 48-hr EC 50 , 0.0038 mg/l; green alga (Pseudokirchneriella subcapitata) 72-hr EbC 50 , Ͼ10 mg/l. 2,3) Aquatic invertebrates are one of the most diverse taxonomic classes in terms of ecology and physiology 4,5) and are known to exhibit species-dependent susceptibility to chemicals, including pesticides. 6) Although Daphnia magna is the typical species used to assess the impact of a chemical on aquatic invertebrates due to the ease of handling and availability of a large ecotoxicological database, 7) cladocerans have been found to be less susceptible to certain insecticides than other invertebrates, such as midges. 8) Midges and amphipods are the other important classes from their ecology in the aquatic environment and are known to show different susceptibility to chemicals, including pesticides. 9) Recently, ecotoxicological testing methods have been recommended by the Organization for Economic Cooperation and Development (OECD), the Office of Chemical Safety and Pollution Prevention Substances, United States Environmental Protection Agency (OPPTS), the American Society for Testing and Materials (ASTM) and Ministry of Agriculture, Forestry and Fisheries, Japan (JMAFF) 9-12) for both species as a standard species. From these viewpoints, the acute toxicity of I to larval midge Chironomus yoshimatsui and adult amphipod Hyalella azteca was investigated in the present study. Furthermore, the metabolism of I in these invertebrates as well as its body residues was briefly examined to explain the apparent difference in its acute toxicity. Materials and Methods Chemicals[ 14 C]-I uniformly labeled at dichlorophenyl ring ( Fig. 4; specific activity, 9.70 and 9.87 MBq/mg; radiochemical purity, 95.7-97.1%) as well as non-radiolabeled I were prepared in our laboratory. The following authentic standards of potential metabolites were also prepared in our laboratory 13,14) with chemical purities of 98.0 to 98.8%: 3,5-dichloro-4-(3-(5-trifluoromethyl-2-pyridyloxy)propoxy)phenol (II) and 2-{3,5-dichloro-4-[3-(5-trifluoromethyl-2-pyridyloxy)propoxy]phenoxy}acetic acid (III). Hydrogenated caster oil (HCO-40) was purchased from Nikko Chemicals and used without treatment. Acute toxicity and related metabolism of pyridalyl inChironomus yoshimatsui and Hyalella azteca Mitsugu MIYAMOTO* and Toshiyuki KATAGI Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 2-1, Takatsukasa 4-chome, Takarazuka, Hyogo 665-8555, Japan (Received April 12, 2010; Accepted June 22, 2010) Acute toxicity and metabolism of a new insecticide pyridalyl were examined in the larval midge Chironomus yoshimatsui and adult amphipod Hyalella aztec...

Metabolism, bioaccumulation, and toxicity of pesticides in aquatic insect larvae

“…metabolize OP pesticides [25][26][27][28][29] via either oxidative desulfurization to the respective oxon or hydrolysis to the corresponding phenols. The oxidative dealkylation 23,32,33) at N, O, and Sn atoms and enzymatic hydrolysis [22][23][24] of amides and car- Exp. Cond.…”

“…The spectrophotometric assay of the CaE activity is generally conducted by using α-and β-NA as substrates. Its specific activity (nmol/min/mg protein) seems to be lower in black flies , 57,58) the caddisfly (92), 56) and midges (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36), 47,59) as compared with D. magna (220) 60) and Hyalella curvispina (amphipod) (101). 61) Although the number of tested substrates is limited, the CaE activity decreased as follows: black fly>caddisfly≥mayfly>damselfly.…”

A Reduced Model for Bioconcentration and Biotransformation of Neutral Organic Compounds in Midge

“…They influence the energy flow of aquatic ecosystems and represent a large portion of the biomass in the lower trophic levels (Failla et al 2015). The midges Chironomus dilutus and C. riparius are easy to culture and maintain in a laboratory environment (Vogt et al 2007) and thus are ideal test organisms for various ecotoxicological tests (Lydy et al 2000; Leslie et al 2004; Organisation for Economoic Co‐operation and Development 2004; Miyamoto and Katagi 2010). Overall, midge species are useful indicators for contaminant field monitoring, and larval stages of midges are convenient test organisms.…”

Qualitative and quantitative determinations of pyridalyl and metabolites in excrement of two representative Lepidoptera pests

“…3,[8][9][10][11][12] Generally, pesticides interact with the target enzyme in the metabolic organ, and certain physiological functions of pests are thus inhibited. 13,14 In this sense, metabolites of pyridalyl in Lepidoptera pests, as well as their metabolic pathways, would be helpful for nding out the target enzyme. 15,16 Related research has focused more on the physiological and biological safety of pyridalyl.…”