Effect of soil management on Heterorhabditis bacteriophora GPS11 persistence and biological control in a vegetable production system

Abstract

Soil habitat conditions that promote abundance and persistence of entomopathogenic nematodes (EPNs) might be encouraged by reduced tillage and compost amendments. We hypothesized that altered soil management with reduced tillage, cover crops (clover and barley), and compost (100kg of N/ha), would increase survival and biocontrol services of EPNs, compared with conventional management. Field trials were conducted at the Ohio Agricultural Research and Development Center Muck Crops Research Station, Huron County, OH in 2010 and 2011. Plots were planted with carrots. EPNs, Heterorhabditis bacteriophora GPS11, were released and their survival was compared between the two soil management regimes by sampling over a period of 8weeks using in situ bait traps containing Galleria mellonella. Repeated measures analysis of variance did not show significant differences between the two soil management regimes in the pattern of H. bacteriophora survival over time or during any evaluation in either year, except 2weeks after cadaver application in 2010 when the EPN population was significantly greater in the conventional than in the alternative soil management regime. Although treatment effects were generally not significant, statistically significant increase in nematode population densities between the 2years of the study, despite generally poor weather conditions following EPN release in the second year, provide encouraging evidence that populations of these biological control agents could increase in vegetable production fields. However, longer periods may be required for clearly distinguishable increase in EPN population density, persistence, and biological control services in the alternative soil management treatments.