Prevalence of temnocephalids on cultured and wild Cherax quadricarinatus in Malaysia

The introduction of the crayfish Cherax quadricarinatus into new areas of Malaysia resulted in the introduction of new parasites that harmed other aquatic organisms. A study was conducted to determine the prevalence and sites specificity of temnocephalids in wild and cultured Cherax quadricarinatus. In this study, 33 wild (Melaka) and 32 cultured (Johor) C. quadricarinatus were sampled in January 2020. The prevalence of the parasite was determined using dissecting microscopes and their sites specificity were compared. The prevalence (P) and mean intensity (MI) of temnocephalids in wild crayfish were 93.94% and 35.13%, whereas in the cultured crayfish were 100% and 18.31%, respectively. The temnocephalid species were identified as Diceratocephala sp., Craspedella sp., and Decadidymus sp. The prevalence of adults and eggs of Decadidymus sp. was found to be significant in cultured C. quadricarinatus (p < 0.05). Significant differences were observed by adult Diceratocephala sp. and Craspedella sp. on the cephalothorax and walking legs, and in the gills and gill covers of wild C. quadricarinatus, respectively. These findings showed that the cultured C. quadricarinatus had a higher temnocephalid infestation compared to the wild C. quadricarinatus. These different temnocephalid species occupied different niche areas, but factors accounting for their distribution on C. quadricarinatus need further investigation.