Entomopathogenic nematode distribution and edaphoclimatic conditions in the Cerrado of Minas Gerais, Brazil

Based on the high diversity of Brazilian fauna and flora, edaphoclimatic conditions in the Cerrado of Minas Gerais, and the situation of utilization of EPNs in Brazil, a survey was conducted in order to relate the presence of these organisms with the physical and chemical attributes of the soil, combined with precipitation. To this end, soil samples were collected in areas with diversified vegetation types in Monte Carmelo, MG, at Juliana Farm. The samples were obtained every 15 days for 6 months. From each spot, soil samples (about 500 g) were collected for soil moisture characterization, nematode isolation and determination of pH, organic matter, potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), potential acidity (H + Al) and precipitation data (mm). Three populations of entomopathogenic nematodes of the Heterorhabditis amazonensis species were isolated in Cerrado stricto sensu and Gallery forest areas. The occurrence H. amazonensis could not be considered restricted to specific soil condition, as organic matter, humidity, pH, Ca, K, Mg and H + Al, especially considering the organic matter and K values, which had variable levels between the places of collection. The p values of the positive soil samples were at a lower level than the mean of the Gallery forest and Cerrado, and at the same level as maize and pasture area. The soil moisture in the Cerrado area increased with the higher values of precipitation; however, in the Gallery forest area this association was not observed. Also, the nematodes were isolated when the temperature began to decrease.