Do bio-insecticides affect only insect species? Behavior, regeneration, and sexual reproduction of a non-target freshwater planarian

Bio-insecticides have been increasingly used worldwide as ecofriendly alternatives to pesticides, but data on their effects in non-target freshwater organisms is still scarce and limited to insects. The aim of this study was to determine the lethal and sub-lethal effects of the bio-insecticides Bac Control (based on Bacillus thuringiensis kurstaki-Btk) and Boveril (based on Beauveria bassiana-Bb) on regeneration, behavioral, and reproductive endpoints of the freshwater planarian Girardia tigrina. The estimated LC50-48h were > 800 mg a.i./L for Btk and 60.74 mg a.i./L for Bb. In addition, exposure to Btk significantly decreased locomotion and feeding activities of planarians (lowest observed effect concentration (LOEC) of 12.5 mg a.i./L Btk) and fecundity rate (LOEC = 3.12 mg a.i./L Btk), whereas exposure to Bb significantly delayed regeneration (LOEC = 0.75 mg a.i./L Bb) and decreased fecundity rate (1.5 mg a.i./L Bb) of planarians. Thus, both bio-insecticides induced deleterious sub-lethal effects on a non-insect freshwater invertebrate species. However, only Bb-based formulation affected the survival, fecundity rate, and regeneration at concentrations below the maximum predicted environmental concentration (PEC = 247 mg/L). Thus, care should be taken when using such formulations as alternatives to chemical insecticides near aquatic ecosystems.

Automated summary

Bio-insecticides Bac Control and Boveril had lethal and sub-lethal effects on freshwater planarians, with Bac Control affecting behavior and fecundity, and Boveril mainly affecting regeneration and fecundity. Bb-based formulation had more pronounced effects on survival, fecundity, and regeneration at lower concentrations compared to Btk-based formulation. Careful consideration is needed when using bio-insecticides near aquatic ecosystems.