GLYPHOSATE AND PARAQUAT HERBICIDES’ ACUTE EXPOSURE AND CHRONIC EFFECTS ON YELLOW MEALWORMS, TENEBRIO MOLITOR

Abstract

Glyphosate and paraquat are broad-spectrum and non-selective herbicides used for weed control worldwide. Their potential impacts on alterations in non-target organisms are known. In this study, we reported the effects of glyphosate and paraquat on the mortality and growth response of Tenebrio molitor larvae after 48-hr exposure to glyphosate and paraquat. The results indicated that the LC50 value for paraquat (LC50 = 0.31 mg/cm2) was lower than for glyphosate (LC50 = 1.77 mg/cm2), indicating that paraquat was more acutely toxic to T. molitor. At evaluated concentrations, the third- and fourth-instar larvae exposed to glyphosate showed less impact on body length and weight compared to the control in the post-exposure development of surviving larvae. Most pupae developed from surviving larvae of glyphosate exposure showed incomplete emergence of adults from their cocoons, with most dying during ecdysis. Some emerging adults survived, but their moults broke into pieces. In contrast, following exposure to paraquat, surviving larvae showed more shrinkage of body length and weight loss at higher doses than at lower doses. Our results regarding a non-target organism suggest that both glyphosate and paraquat should be used with caution.