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Postharvest Pathology and Mycotoxins

Relation of Insect Damage, Vector, and Hybrid Reaction to Aflatoxin B₁ Recovery from Field Corn. J. C. LaPrade, Assistant Professor of Plant Pathology, Pee Dee Experiment Station, Florence, South Carolina 29503 ; A. Manwiller, Associate Professor of Agronomy, Pee Dee Experiment Station, Florence, South Carolina 29503. Phytopathology 67:544-547. Accepted for publication 26 October 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-544.

Mature ears from nine short-season commercial corn hybrids were harvested and separated into three different insect-damage severity levels due mostly to the rice weevil, Sitophilus zeamais. Thirty-nine percent of these naturally infested ears had detectable levels of aflatoxin B₁. The lightly, moderately, and severely damaged ears had an average of 0, 3.0, and 16.2 μg/kg of aflatoxin B₁, respectively. Artificially-infested rice weevils apparently were unable to infect ears of corn in the field when they were caged on the ears in fiberglass mesh bags. Only two of 28 ears each exposed to 25 weevils taken from a corn storage bin contained detectable levels of aflatoxin B₁. Two noninfested control ears were positive at a concentration of 2.0 and 15.0 μg/kg of aflatoxin B₁, respectively. In these tests, the rice weevil appeared to be a nonvector or very inefficient vector of Aspergillus flavus, since no detectable aflatoxin B₁ was found in corn on which the infested weevils had fed. Significantly less aflatoxin B₁ was recovered from corn of the South Carolina long-season cultivars and from their opaque-2 counterparts artificially inoculated with A. flavus than from nine short-season hybrids similarly inoculated.