Genetic Parameters for Host-Response to Acanthocephaliasis Caused by the Endoparasite Neoechinorhynchus Buttnerae in the Amazon Fish Colossoma Macropomum

Tambaqui (Colossoma macropomum) is the main native fish produced by Amazon aquaculture. However, the production chain of this fish has been significantly affected by acanthocephaliasis, caused by the endoparasite Neoechinorhynchus buttnerae. The selection of superior genotypes for resistance and resilience to acanthocephaliasis is a fundamental approach to improve production in the context of environmental sustainability and food security. Thus, the objectives of this study were to 1) conduct an experimental challenge against the endoparasite N. buttnerae in tambaqui, and 2) determine the genetic parameters of disease traits caused by N. buttnerae in an experimental breeding population of tambaqui. Estimation of genetic parameters was performed using a genomic relationship matrix (SNPs data) obtained from an experimental challenge performed in 70 full -sib families. The experimental challenge was successfully performed in three replicate tanks, using the parasite eggs in the ichthyoplankton as source for a natural route of infection, which in turn was induced through oral filtration the plankton. The total gain in body weight of all individuals was measured during the infestation period, as a measure of Resilience (RSF) and averaged 42 g (SD = 21.8). The average parasite abundance per animal at the end of the challenge period, indicating Resistance (RTCT), was about 205.2 parasites (SD = 178.6). The heritability estimates for these traits ranged from 0.17 +/- 0.04 to 0.20 +/- 0.04, indicating the presence of low to moderate heritability levels for host response against N. buttnerae in tambaqui. Genetic correlations between resistance and resilience traits were consistently negative (favorable) and statistically significant, ranging from -0.512 +/- 0.134 to -0.252 +/- 0.166. These results suggest the possibility of selecting animals for both resistance and resilience simultaneously. The significant genetic variation found for N. buttnerae resistance and favorable genetic correlations with resilience in tambaqui indicated that selecting superior genotypes is a viable approach to reduce the impact of acanthocephaliasis disease in aquaculture.