Study on the Toxic Effect of Cypermethrin on Using Earthworm to Treat Vegetable Waste

PurposeTo study the effect of cypermethrin residue in vegetable waste on the growth, reproduction and development of earthworm.

MethodsAccording to GB/T 21809—2008, short-term exposure tests and 28-day feeding tests were conducted to study the effects of chlorocyanide residues in vegetable waste on radon antioxidant enzyme activity, tissue pathological changes, and body cavity cells.

ResultsWhen earthworms were fed with vegetable wastes containing cypermethrin for 7 days, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) increased significantly (P<0.05), and the proportion of early apoptosis of body cavity cells increased, while the activity of SOD decreased significantly (P<0.05) after 24 h of exposure, and the proportion of early apoptosis of body cavity cells increased. Exposure to cypermethrin for 48 h and 72 h and feeding of vegetable wastes containing cypermethrin for 14 and 21 days damaged the antioxidant system, resulting in a significant decrease in SOD and POD (P<0.05), MDA content increased significantly (P<0.05), and an increase in the proportion of late apoptosis in body cavity cells. After 28 d feeding, the activities of SOD and POD of earthworms decreased significantly (P<0.05). The results of feeding test showed that on the 14th day, in the medium and high dose groups, the epithelial cells of body wall fell off, the intestinal cavity expanded, the intestinal epithelial cells degenerated and necrotized, the yellow cells necrotized and the nuclei disappeared; on the 14th day, the early and late apoptosis of coelom cells reached the maximum and then decreased gradually.

ConclusionWhen the dose of cypermethrin was higher than 4.472 μg/cm², the earthworm suffered antioxidant damage after being exposed; when the content of cypermethrin reached 212.4 mg/m² of vegetable waste, damage can be caused to earthworm antioxidant system and its body wall, intestinal wall. Therefore, in the process of using earthworm to deal with vegetable waste, we must strictly control the residues of cypermethrin in vegetables, in order to ensure the earthworm in the process of feeding can normal growth, development, reproduction, so as to decompose vegetable waste.