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The marine amphipod Parhyale hawaiensis is able to regenerate its appendages, limbs and tissues. The objective of this study was: (i) verify whether the regeneration of P. hawaiensis antenna can be used as an endpoint in a miniaturized toxicity test system (12 well microplates, 5 mL) and, (ii) apply this endpoint in the toxicity assessment of dimethyl sulfoxide (DMSO), a organic solvent commonly used in toxicity tests, and diflubenzuron (DFB), a growth regulator insecticide. The average regeneration time of fifty percent of the population (RT50) in reconstituted saltwater tests was 16.7 days. DMSO induced the regeneration concentrations above 0.02%. As expected for chitin syntesis inhibitor, DFB strogly inhibited the antenna regeneration with a 28 d-EC50 = 0.5 μg/L. Thefore, we conclude that regeneration time can be used as endpoint in a cost effective miniaturized toxicity test, with time < 35 d. Moreover, DMSO should not be used as a solvent.

Parhyale hawaiensis is a marine amphipod of circumtropical distribution and has been used in acute ecotoxicological tests. However, sub lethal responses are important endpoints in ecotoxicology because they allow the assessment of effects at environmental concentrations. P. hawaiensis has the ability to regenerate its appendages, limbs and tissues after an injury or loss during their entire life. Data on effects of toxicants on appendages regeneration of marine organisms are still scarce. Regeneration can be used as an ecotoxicological endpoint to assess potential teratogenic compounds and their impact on stem cells. Thus, the aim of this study was to obtain data on regeneration of antennae of P. hawaiensis to determine the viability this endpoint on toxicity tests.

Parhyale hawaiensis is an marine amphipod and attractive model organism for ecotoxicology. The insect growth regulator diflubenzuron (DFB) is a chitin syntheis inhibitor insecticide with have pronounced toxic effects on non-target organisms, especially insects and crustaceans. This study aimed to evaluate the toxicity assessment of diflubenzuron using a miniaturized approach for chronic test with Parhyale hawaiensis, previousily standarized in our reasearch group.