Frequencies and population densities of parasitic nematodes in Costa Rican pineapple plantations

An analysis of the plant-parasitic nematodes found in pineapple plantations in the counties of Pococi, Puntarenas, San Carlos, Sarapiqui and Upala of Costa Rica from 2008 to 2016 was carried out. Nematodes were extracted from roots by maceration or maceration-centrifugation methods. Data were subjected to frequency analysis in PC-SAS and the absolute frequency was calculated for each individual genus. Three plant parasitic nematodes were detected, and based on their frequencies and population densities, the importance of nematode genera in decreasing order was: Helicotylenchus spp.>Pratylenchus spp.>Meloidogyne spp. Helicotylenchus spp. was the most abundant nematode accounting for 7.6 to 76.2% of the overall root population, followed by Pratylenchus spp. accounting for 11.5 to 92.4% of the population across the years analysed. From a total of 5,352 root samples, 67% contained Helicotylenchus spp., 38% Pratylenchus spp., 1% Meloidogyne spp., and when the three nematodes present were pooled (total nematodes), 74% of samples had nematodes. Large numbers of samples with nematode populations above the economic threshold suggested 5 nematodes g(‑1) of fresh roots were observed in all the years, months and counties. The statistical differences (P<0.0001) detected for nematode frequencies among years, months and counties more likely are associated to the high number of samples included in each year, month and county, since variations in frequencies for each nematode genus were small.