Sodium hypochlorite as an Artificial Exsheathment Medium for Nematode Larvae: Limitations for Application

Abstract Sodium hypochlorite (NaOCl) has largely been used as an artificial exsheathment medium for nematode larvae in various studies such as evaluating the efficacy of anthelmintic drugs, assessing the resistance of nematodes to anthelmintics, evaluating plant bioactive products as anthelmintics, or in nematode viability assays because of its unique capacity for tissue dissolution. Doubts, however, exist that the compound affects the viability of the exsheathed larvae. The present study’s objective was to exclude or confirm possible negative effects of the compound using strongylid third-stage larvae of donkeys’ origin. Visual larval immobility and gross morphological changes were adopted as criteria for assessment of viability following treatment of larvae with 0.025, 0.05, 0.1, 0.2, 0.3, or 3% NaOCl solutions. Larvae were examined 10, 5, or 3 min after treatment. The results indicate there is a threshold beyond which viability is impaired. A concentration of 0.025% produced no effect on the viability of larvae (the optimum concentration) for as long as 10 min following treatment (the effective time). It is proposed that in situations where the optimum concentration has been determined, it is necessary to establish if exsheathment can be produced within the respective effective time limit.