Relationship of Damage from the Lesser Cornstalk Borer to Aspergillus flavus Contamination in Peanuts²

The ability of larvae of the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), to augment contamination of peanut pods with aflatoxigenic fungi, Aspergillus flavus Link and A. parasiticus Speare (A. flavus-type fungi), was investigated in laboratory and field studies. Aflatoxigenic fungi were found in or on frass from 28.6% of field-collected larvae and in 8.9% of sterilized and macerated larvae. More aflatoxigenic fungi tended to be found in pods from untreated plots than in plots treated with chlorpyrifos in field trials. Contamination of pods or seeds with A. flavus-type fungi was positively correlated in all four trials with scarification of pods, and this relationship has been quantified. Since appropriate insecticide treatments can decrease populations of lesser cornstalk borers, which would decrease pod scarification, these same treatments may decrease contamination with aflatoxigenic fungi. Treatment thresholds for the lesser cornstalk borer need to be reconsidered based upon this information.