The Mexican axolotl's (Ambystoma mexicanum) early development and survival is affected by commercial grade malathion and dichlorvos organophosphorus pesticides

The wild population of the Mexican axolotl (Ambystoma mexicanum) is subject to a dramatic decline as a consequence of deteriorating conditions in its natural habitat, Xochimilco. The common use of organophosphorus pesticides (OPPs) in the region affects water quality and is partially responsible for the axolotl decline. This could be a consequence of the delicate nature of axolotls, which are struggling to survive under contaminated conditions at early stages of development. In this regard, we aimed to extend the knowledge of OPPs effect on the survival of axolotls in their early stage of development, within the context of detrimental environment conditions using commercial grade OPPs. Fertilized axolotl eggs were treated with malathion (MLT), dichlorvos (DDVP), and a depurated group in which the OPPs exposure was stopped earlier, as well as an untreated control group. Changes in hatching, survival, size, and morphology were monitored and analyzed in embryos and early larvae. Our results showed that MLT and DVPP accelerate egg hatching and mortality even after the early removal of OPPs from the medium. OPPs also caused a reduced size and morphological abnormalities. It is proposed that such abnormalities would jeopardize the survival of the wildlife axolotl. Our results suggest that OPPs can cause irreversible damage to the axolotl embryos, stopping their normal development, causing death and reducing their chances of survival in their natural environment.