## 5 Conclusions  
This investigation revealed that _P. insularum_ exhibited the same metal sensitivity as other freshwater gastropods. Cu was the most harmful to _P. insularum_, followed by Cd, Zn, Pb and Ni. The acute toxicity tests revealed that _P. insularum_ is more susceptible to Cu than Cd, Ni, Pb and Zn, which is consistent with the LC\({}_{50}\) values reported in the literature for most invertebrate species. This study indicated that _P. insularum_ may also be used as a biomonitor for acute and subacute Cd, Cu, Ni, Pb and Zn exposures. Since _P. insularum_ is widely spread in urban and suburban regions, it is incredibly valuable for ecotoxicological research. This study demonstrated that _P. insularum_ may be a biomonitor of potentially toxic metal contamination. Using _P. insularum_ as a test organism, this study provided essential baseline data for PTM toxicity. Changes in the snail population due to PTM exposures may potentially influence the predation behavior of predators, which is an interesting area for future studies.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13021042/s1](https://www.mdpi.com/article/10.3390/app13021042/s1)]([https://www.mdpi.com/article/10.3390/app13021042/s1](https://www.mdpi.com/article/10.3390/app13021042/s1)), Table S1: Nominal and measured concentrations (mg/L) of Cd, Cu, Ni, Pb and Zn in the toxicity test for the _Pomacea insularum_ of two different sized groups (Shell lengths, small 0.50-0.70 cm; large: shell 1.50-2.20 cm); Table S2: Mortality of individuals (_Pomacea insularum_) for the small sized group (Shell length: 0.50-0.70 cm) collected after four different periods of exposure to a series of different concentrations of Pb, Ni, Cd, Zn and Cu; Table S3: Mortality of individuals (_Pomacea insularum_) for the large-sized group (Shell length: 1.50-2.20 cm) collected after four different periods of exposure to a series of different concentrations of Cd, Cu, Ni, Pb and Cu, Zn.  
**Author Contributions:** Conceptualization, C.K.Y.; Formal analysis, B.H.P. and C.K.Y.; Funding acquisition, C.K.Y.; Investigation, B.H.P., C.K.Y. and W.H.C.; Methodology, B.H.P., C.K.Y., K.K. and M.C.O.; Project administration, C.K.Y. and W.H.C.; Resources, K.K., H.O., M.K., A.N., M.S.I. and W.S.T.; Supervision, C.K.Y.; Validation, K.K., R.A., H.O., Y.H., M.S., M.K., M.C.O. and A.N.; Visualization, R.A. and Y.H.; Writing-original draft, C.K.Y. and B.H.P.; Writing--review and editing, W.H.C., K.K., R.A., H.O., Y.H., M.S., M.K., M.C.O., A.N., M.S.I. and W.S.T. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors would like to acknowledge the financial support provided through the Research University Grant Scheme (RUGS), [Vote no.: 9322400], by Universiti Putra Malaysia, and also Fundamental Research Grant Scheme (FRGS) Phase 1/2016 [Vote no. 5524953] by Ministry of Higher Education Malaysia.