Effects of two biopesticides and salt on behaviour, regeneration and sexual reproduction of the freshwater planarian Girardia tigrina

Microbial insecticides are being used as ecologically-friendly alternatives to traditional insecticides. However, their effects have been poorly investigated on non-target freshwater species, with exception of a few insect species. Moreover, combined effects of microbial insecticides with other environmental stressors, such as salinity, have never been investigated. Thus, our goal was to assess the effects of Bac-Control (R) (based in Bacillus thuringiensis - Btk) and Boveril (R) (based in Beauveria bassiana - Bb) with increasing salinities (NaCl) on freshwater planarian Girardia tigrina. It has been reported that increased salinity levels affect freshwater organisms compromising their survival by triggering adaptation processes to cope with osmotic stress. Our results showed delayed regeneration, decreased locomotion and feeding on planarians exposed to NaCl, whereas their sexual reproduction was not affected. Both microbial insecticides impaired feeding, locomotor activity, regeneration, and sexual reproduction of planarians. Planarians exposed to microbial insecticides compromised their progeny. Therefore, microbial insecticides might not be ecologically friendly alternatives to chemical insecticides. Interestingly, harmful effects of microbial insecticides with increasing salinities showed an inadequate response of planarians to cope with induction of their immune response and osmoregulation.

Automated summary

Microbial insecticides have negative impacts on planarians, affecting their regeneration, locomotion, feeding, and sexual reproduction. When combined with increasing salinities, the harmful effects on planarians and their progeny are exacerbated, indicating an inadequate response to immune and osmoregulation processes.