Host Compatibility of the Temnocephalid Diceratocephala boschmai: Experimental Transmission Between Invasive Cherax quadricarinatus and Native Macrobrachium rosenbergii in Malaysia.

BACKGROUND

The introduction of host-associated symbionts by invasive species threatens native aquatic biodiversity through symbiont spillover and host switching. This study investigated the experimental host-specificity and transmission potential of Diceratocephala boschmai from invasive Cherax quadricarinatus to the native giant freshwater prawn Macrobrachium rosenbergii.

METHODS

Briefly, temnocephalid-infested C. quadricarinatus were exposed to symbiont-free M. rosenbergii and C. quadricarinatus for 30 days. Thereafter, symbiont transmission was assessed, and host hemolymph parameters, including total hemocyte count (THC), differential hemocyte count (DHC), glucose, and protein concentration, were evaluated.

RESULTS

Successful transmission was observed in 93.33% of C. quadricarinatus, with both adult worms and egg capsules detected, whereas no transmission was observed in M. rosenbergii. THC was significantly higher in experimentally infested C. quadricarinatus (TCq) than in non-infested C. quadricarinatus (NCq) (p<0.05). DHC and glucose concentrations differed among host populations. Total protein concentration also differed significantly among host populations, with NMr exhibiting higher concentrations than the other groups, whereas no significant difference was detected between TCq and NCq.

CONCLUSION

The results demonstrate successful infestation of C. quadricarinatus but not in M. rosenbergii under the experimental conditions, suggesting differences in host compatibility. Increased THC in experimentally infested C. quadricarinatus indicates a cellular response to symbiont exposure, although experimental stress may also have contributed. Overall, the findings provide restricted host compatibility and highlight that invasive C. quadricarinatus may serve as a reservoir for D. boschmai, facilitating its persistence and dissemination in freshwater ecosystems.