Aspectos ecológicos de la relación parasitaria entre larvas de contracaecum sp. nematoda, anisakidae y serrasalmus spilopleura kner, 1860, pisces, characidae en poblaciones naturales del nordeste argentino / Ecological relationships between contracaecum sp. larvae and the host serrasalmus spilopleura kner, 1860 in natural populations of northeastern Argentina

ABSTRACT

From february 1987 to february 1989, the populational biology of contraceacum sp. (larvae) in its paratenic host, the fish serrasalmus spilopleura kner, 1860, was studied in two ponds in a subtropical permanent habitat northeastern of Argentina. Fishes from Ramada Paso pond presented 80 percent of prevalence asn 1 to 132 larvae per fish while fishes from aeroclub pond presented 63 percent of prevalence and 1 to 184 larvae per fish. Fishes collected from aeroclub pon have shown a high prevalence of infection during the first period of study (1987), diminishing the folowing year. In fishes from Ramada Paso pond the prevalence varied not significatively during the two years. Prevalence and mean intensity of infection increase with body lengh and weigth of the hosts. Sex of hosts is not an influential factor in parasitic level. The lenitic closed environmental (Ramada Paso pond) evidenced the greatest larvae mean intensity and prevalence. Althougt, the lenitic open environmental (aeroclub pond) showed the greatest parasitic number of individuals in an infrapopulation. The spatial dispersion in both ponds were agregated and fit well a negative binomial model. Neverthelees, the aeroclub pond presented the greastest overdispersion