Chronic toxicity of commercial chlorpyrifos to earthworm Pheretima peguana.
A chronic toxicity study was conducted in earthworms (Pheretima peguana) exposed to soil spiked with chlorpyrifos at concentrations of 0, 0.1, 1, 10, and 100 mg/kg soil dry matter for 7, 14, and 28 days. The integrity of the coelomocyte lysosomal membrane, nervous system, and male reproductive tissue was monitored using, respectively, the neutral-red retention assay, acetylcholinesterase (AChE) enzyme assay, and histomorphology of spermatogenic cells in the seminal vesicles and cocoon production (at 28 days after 28 days' exposure). Chlorpyrifos decreased the coelomocyte neutral-red retention time (NRRT) significantly (p < 0.05) at concentrations > 0.1 mg/kg soil as early as day 7 of exposure and was dose- and time-dependent. Chlorpyrifos inhibition of AChE activity was greater at day 7 than at day14 (p < 0.05) indicating possibly nerve recovery. Chlorpyrifos induced concentration-dependent damage to spermatogenic cells and cytophores in premature stages. The number and size of premature, maturing, and fully mature spermatogenic stages were increased at low concentrations (<1 mg/kg) but a number of these maturation stages declined at higher concentrations (10 and100 mg/kg) on day 28. The most severe effects were observed in the maturing and fully mature stages at the highest chlorpyrifos concentration, and this had an adverse impact on cocoon production and cocoon viability. Collectively, the results suggest induction of widespread effects on multiple organ systems in P. peguana exposed to chlorpyrifos. Although NRRT and AChE activity were the most sensitive of the biomarkers, cocoon production and cocoon viability could still be considered as diagnostic tools for monitoring effects from low-dose long-term chlorpyrifos toxicity and for evaluating population effects. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1450-1459, 2016.
Biology Department, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand.
Ptumporn
P
Muangphra
Biology Department, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand.
Kampanat
K
Tharapoom
Biology Department, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand.
Nongnuch
N
Euawong
Biology Department, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand.
Suluck
S
Namchote
Faculty of Agriculture and Life Sciences, PO Box 85084, Lincoln University, 7647, Canterbury, New Zealand. Ravi.Gooneratne@lincoln.ac.nz.
Ravi
R
Gooneratne
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D004390:Chlorpyrifos / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D008018:Life Cycle Stages / Q000187:drug effects; D008297:Male; D009499:Neutral Red / Q000494:pharmacology; D009835:Oligochaeta / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D012989:Soil Pollutants / Q000633:toxicity*; D013091:Spermatogenesis / Q000187:drug effects; D036401:Toxicity Tests, Chronic
D015415:Biomarkers; D007306:Insecticides; D012989:Soil Pollutants; D009499:Neutral Red; D000110:Acetylcholinesterase; D004390:Chlorpyrifos
acetylcholinesterase; chlorpyrifos; cocoon production; earthworm; histomorphology; neutral red retention time