Hepatopancreatic necrosis disease (HPND) in Chinese mitten crab Eriocheir sinensis tightly linked to low concentration of two insecticides

Abstract

To date, hepatopancreatic necrosis disease (HPND) in Eriocheir sinensis is causing huge financial losses to the aquaculture industry while the cause of HPND remains unclear. Our previous study has implied that HPND is probably relevant to the damages caused by insecticide residues. In this work, the comparative studies regarding histopathology and trends in immune‐related/detoxifying enzymes activities of the crabs were performed between exposed to the low concentration of insecticides (i.e. β‐cypermethrin 8.52 × 10−12 g/L and trichlorfon 5 × 10−5 g/L) in a long‐term (90‐days) and suffered from HPND. The concentration was obtained by a median‐lethal concentration (LC50) and a safe concentration (SC), and it was 10 times lower than the safe concentration in this experiment. This work's principal aim was to investigate the potential chronic effects of low concentrations of insecticides exposure on crabs and their relevance with HPND. As a result, crabs exposed to the low concentration of insecticides caused similar clinical symptoms and severity in hepatopancreas and other tissue damages like HPND. Meanwhile, catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM) and carboxylesterase (CarE) enzymatic activity increased after exposure to the two insecticides and then decreased in the later stages, while the activity of glutathione S‐transferase (GSTs) has barely changed. Results of enzymatic activity indicated that the two insecticides induced oxidative damage to the hepatopancreas of E. sinensis. These evidence indicated that the chronic damage caused by the low concentration of insecticides, which is considered insecticide residue, might be part of the causes of HPND in crabs. The present work may enhance our understanding of the pathogenesis of HPND and provide a theoretical basis for the management of intensive crab aquaculture.

Metatranscriptomic Analysis Reveals an Imbalance of Hepatopancreatic Flora of Chinese Mitten Crab Eriocheir sinensis with Hepatopancreatic Necrosis Disease

“…Crab HPND was suggested to be the result of both autophagy and apoptosis induced by some unknown abiotic factors including pesticides, toxins from environmental bacteria and algae, chemical fertilizer, antibiotics in food, and farming water [ 2 , 17 ]. This speculation is supported by epidemiological investigations that crab HPND may result from hypoxia and pesticide residues, high pH in surrounding waters, massive aquatic plants and abundance of cyanobacteria, or in water environments with empty-illumination, without aquatic plants and reduced feeding, or hypoxia and pesticide residues [ 2 , 4 , 9 , 11 , 13 ]. The association between 55 variables and HPND was assessed.…”

“…The aetiology of HPND was explored in the pathogens [ 1 , 4 ], pathological changes [ 2 , 8 , 17 ], ecotype [ 9 , 10 , 11 , 14 ], hepatopancreatic flora [ 15 ], the transcriptome of hepatopancreas [ 1 , 6 , 17 ], metabolite profiling of the hepatopancreas [ 12 ], and offspring seed and epidemiological surveys [ 8 , 13 ]; however, the aetiology of HPND crab remains unidentified.…”

“…Several studies have indicated that increased occurrence rates of HPND with increased pesticide applications [ 9 , 10 , 12 ]. A high concentration of propamocarb was detected in the hepatopancreas of crabs with HPND [ 11 ].…”

“…A high concentration of propamocarb was detected in the hepatopancreas of crabs with HPND [ 11 ]. Moreover, crabs exposed to a low concentration of insecticides caused clinical symptoms of HPND [ 9 ]. Interestingly, DEGs in the hepatopancreas between crab with HPND and without HPND were enriched to the metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450, and material metabolism [ 16 ].…”

“…A previous study found that symptoms of crab HPND could be caused by breeding crabs in water with a pH of 9.5–10.0 [ 2 ], and crabs exposed to low concentrations of insecticides caused clinical symptoms of HPND [ 9 ]. Epidemiological investigations suggest that HPND in mitten crabs may result from high a pH in surrounding waters, large aquatic plants and an abundance of cyanobacteria, or hypoxia and pesticide residues [ 10 , 11 , 12 , 13 ].…”