Effect of λ-Cyhalothrin-Loaded Polydopamine Microcapsule Suspensions on Stress Defenses in the Chinese Mitten Crab, Eriocheir sinensis

Abstract

Microcapsule suspension improves the utilization efficacy of pesticides and has been widely developed to alleviate the environmental impact of aquacultural pesticides. However, little is known about the fate and environmental effects of the microcapsule suspensions used in aquatic food production. In this paper, polydopamine (PDA)-suspended microcapsules (PDA-MS) were loaded with 2.5% λ-cyhalothrin (LC) to produce a microcapsule suspension (LC/PDA-MS). The freshwater Chinese mitten crab, Eriocheir sinensis, is an important commercial crustacean in rice−crab co-culture systems, and the toxic effect of LC/ PDA-MS on them was evaluated by measuring LC accumulation and oxidative stress. The results indicated that LC/PDA-MS was not significantly acutely toxic to E. sinensis, with a mean 96 h LC 50 of 6.4 mg/L. Furthermore, chronic toxicity testing showed insignificant side effects of either LC/PDA-MS or blank PDA-MS on the survival and weight gain rate of crabs, although long-term exposure to high levels of LC/PDA-MS (0.60 mg/L) had a negative influence on their hepatosomatic index. Also, LC/PDA-MS can cause oxidative stress in the hepatopancreas of E. sinensis. These results suggest that PDA-coated nanopesticides can be eco-friendly and hence suitable for use in rice−crab co-culture farming.