Efficacy of binary mixtures and antagonistic effect of Azadirachta indica on Afranamum melegueta against helminth parasites of fish in Epe lagoon

Abstract

This research aims to investigate the efficacy of binary mixtures and interaction of extracts of Azadirachta indica and Afranamum melegueta in reference with praziquantel at Fish Low Observed Effect Concentration (LOEC) on classes of fish parasite species. An in-vitro study was conducted using binary extract mixtures of A.melegueta and A.indica (ratios 1:3, 1:1 and 3:1) respectively on each of the classes of fish helminth parasites and saline solution was used as the control. Average Survival Time (AST) and percentage Reduction in Survival Time (%RST) as measure of sensitivity were estimated for the parasites at varying toxicities (fish 96 h LC5, LC10, LC50) with reference to praziquantel. Saponin and Terpenoid had the highest presence in ethanol mix (water) in A.indica and A.melegueta. The sensitivities of the parasites to the extracts and praziquantel in decreasing order is; A.melegueta (singly) > Praziquantel > 3:1 mix > 1:1 mix > 1:3 mix > A.indica (singly). Increase in the proportion of A. indica decreases the combined effect of the mixtures on the parasites, thereby, decreasing the effect of A. melegueta when acting singly. Tenuisentis sp, an acanthocephalan showed sensitivity of RST >80 % against A. melegueta (singly) similar to praziquantel, the sensitivity was reduced to RST <80 % with 3:1 mix, and significantly reduced to RST close to 60 % with 1:3 mix. Other parasite species had similar trend. There was significant correlation (r > 0.70) between parasite sensitivities to praziquantel and A.melegueta (singly) as well as its binary mixtures at the fish Low Observed Effect Concentration (LOEC). This indicates that the binary extract mixtures could serve as potential alternatives to the use of chemotherapy considering their potency and wide margin of fish host safety.