Mortality of larvae by the separate and combined application of , and .

spp. are a complex of edaphic insect pests that are present in the corn crops () in México, which are usually controlled with increasing dosages of broad-spectrum chemical insecticides. Several entomopathogenic nematode species can produce acceptable control levels of these larvae. However, the synergistic interaction between fungi and entomopathogenic nematodes (EPN) could improve the control of this insect. This study investigates the mortality of larvae of by the effect of the separate or combined application of the fungus M1cog strain (Ma) and the nematodes All strain (Sc) or NJ-43 strain (Sg). In laboratory, dosages of 1 × 10 or 1 × 10 spores/larva and 250 infective juveniles were applied on medium or large size larvae contained in vials with sterilized agricultural soil as the assay arena. The separate application of Ma did not kill any larvae, but Sg and Sc killed 40 and 80% of the larvae, respectively. However, the Ma and Sc combination had an important antagonistic interaction that decreased the mortality to 40%, but the combination Ma and Sg had a slight additive interaction that increased the mortality to 47%. The most determining factor in larvae mortality was the nematode used, with Sg as the species with best performance in 6 of the 12 treatments evaluated and with a maximum effectivity of 80% on medium-size larvae if combined with a low dosage of Ma. The combined application of an entomopathogenic fungus and EPN showed no consistent effects on the mortality percentage of , mostly because the fungus was not isolated from larvae. spp. are a complex of edaphic insect pests that are present in the corn crops () in México, which are usually controlled with increasing dosages of broad-spectrum chemical insecticides. Several entomopathogenic nematode species can produce acceptable control levels of these larvae. However, the synergistic interaction between fungi and entomopathogenic nematodes (EPN) could improve the control of this insect. This study investigates the mortality of larvae of by the effect of the separate or combined application of the fungus M1cog strain (Ma) and the nematodes All strain (Sc) or NJ-43 strain (Sg). In laboratory, dosages of 1 × 10 or 1 × 10 spores/larva and 250 infective juveniles were applied on medium or large size larvae contained in vials with sterilized agricultural soil as the assay arena. The separate application of Ma did not kill any larvae, but Sg and Sc killed 40 and 80% of the larvae, respectively. However, the Ma and Sc combination had an important antagonistic interaction that decreased the mortality to 40%, but the combination Ma and Sg had a slight additive interaction that increased the mortality to 47%. The most determining factor in larvae mortality was the nematode used, with Sg as the species with best performance in 6 of the 12 treatments evaluated and with a maximum effectivity of 80% on medium-size larvae if combined with a low dosage of Ma. The combined application of an entomopathogenic fungus and EPN showed no consistent effects on the mortality percentage of , mostly because the fungus was not isolated from larvae.