Enhanced Infection of Peanut, Arachis hypogaea L., Seeds With Aspergillus flavus Group Fungi Due to External Scarification of Peanut Pods by the Lesser Cornstalk Borer, Elasmopalpus lignosellus (Zeller)1

Abstract

The relationship between injury by the lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), and invasion of peanut, Arachis hypogaea L., pods and seeds by species of the Aspergillus flavus group (A. flavus Link and A. parasiticus Speare) were studied under laboratory and field conditions. In the laboratory, LCB larvae were an excellent vector of an A. parasiticus color mutant (ATCC 24690) to all developmental stages of peanut pods. Fungal invasion and aflatoxin concentration in seeds were higher in immature pods (stage 2–3) than in more mature pods (stage 4–6). Contamination of seeds with ATCC 24690 was directly related to the extent of pod injury by larvae of the LCB. In field studies, over 50% of the LCB larvae collected from peanut were naturally contaminated with species of the A. flavus group. The planting date and harvest date of peanut had little influence on the incidence of fungal contamination of pods and seeds, or on aflatoxin content in seeds. However, increased pod injury by the LCB significantly increased the percentage of seeds infected with species of the A. flavus group. Seeds in pods with only external scarification from larval feeding had a significantly higher percentage of A. flavus group infection than seeds from uninjured pods. Therefore, infection and contamination of visibly uninjured seeds with aflatoxigenic fungi were enhanced by external injury to peanut pods by the LCB.