Utilizing entomopathogenic nematodes with Bt corn hybrids to control corn rootworm, Diabrotica spp.

The Ontario corn (Zea mays L.) industry is in dire need of an additional mode of action to manage corn rootworm (CRW; Diabrotica spp. (Coleoptera: Chrysomelidae)). This soil-borne pest feeds on the corn root system, reducing nutrient uptake and harvestability. If preventative measures aren’t taken, management options are limited once symptomatology is present. Entomopathogenic nematodes (EPNs) have become an appealing biological control method due to the recent rise in resistance to Bacillus thuringiensis (Bt) toxins produced in transgenic corn, and the impracticality of crop rotation and soil-applied insecticides for some growers. EPNs parasitize CRW to diminish larval populations and adult emergence. It was hypothesized that inoculation of soil with EPNs would reduce CRW larval root injury in continuous corn situations. The objective of this research was to evaluate the efficacy of EPNs at controlling CRW in conjunction with current genetic methods and to determine the return on investment for a producer if implemented. Controlled field experiments and field-scale producer environments with a history of CRW were treated with three persistent strains of EPNs. The efficacy of the EPNs was determined by an analysis of nodal root injury, and nematode persistence in the soil during years of study. An economic analysis was conducted to determine the partial profitability required for a corn producer to consider the use of EPNs for CRW control. Utilizing EPNs as an additional mode of action for CRW will lengthen the viability of Bt events and provide innovative and sustainable yield protection for the Canadian corn industry.