Aspergillus flavus and Fusarium verticillioides are well known maize ear rot pathogens and produce mycotoxins that are carcinogenic to humans and livestock. Insect damage to kernels increases the occurrence of these mycotoxins in maize. Many studies focus on the inhibition of aflatoxin production by direct competition with biocontrol agents in vitro. The effects of application of the endophytes to roots via seed treatment on reduction of mycotoxins are not well studied. Here, we present a study that tests the efficacy of symbiotic rhizosphere fungi on improving maize resistance to insects and to contamination with aflatoxins and fumonisins under the field conditions. Two fungal symbionts were applied as seed treatment to B73 inbred and four hybrids and the seed was planted in two locations. Aflatoxin and fumonisin accumulation and the damage by insect herbivory were quantified. Results showed a genotype- and location- dependent effect on mycotoxins and herbivory by these biocontrol candidates with potential for significant reduction of both toxins. We discuss here the potential for this novel approach to mitigate both mycotoxin contamination and yield losses by insect herbivores.