Journal of Economic Entomology (1995) 88, 1776-1782

Jajuk A. Beti, Thomas W. Phillips and Eugene B. Smalley (1995)
Effects of maize weevils (Coleoptera: Curculionidae) on production of aflatoxin B₁ by Aspergillus flavus in stored corn
Journal of Economic Entomology 88 (6), 1776-1782
Abstract: Insects play an important role as facilitators of the aflatoxin-producing fungus, Aspergillus flavus Link, in both preharvest and postharvest corn. The current study investigated the role of maize weevils, Sitophilus zeamais Motschulsky, in enhancing aflatoxin B₁ content in stored corn. In laboratory experiments, aflatoxin B₁ was quantified with an indirect enzyme-linked imrnunosorbent assay (ELISA) on corn following artificial infestation with adult weevils that had each been topically treated with 100 spores of A. flavus. Corn kernels infested with A. flavus-contaminated weevils had significantly higher levels of aflatoxin B₁ than A. flavus-inoculated corn without weevils. The presence of maize weevils resulted in increased kernel moisture content during incubation, and grain moisture was positively correlated with aflatoxin content across treatments receiving spores. Aflatoxin B₁ levels were higher in corn treated with fungus-contaminated weevils compared with corn that was mechanically damaged and inoculated with spores, which in turn had more aflatoxin than undamaged corn treated with spores. Aflatoxin B₁ content in corn increased with time of weevil exposure from 7 to 21 d, but decreased after 28 d of exposure. Aflatoxin levels in infested corn increased significantly with increased numbers of A. flavus-contaminated weevils. Maize weevils carried spores both internally and externally; however, substantial numbers of spores were intimately associated with the exoskeleton of adult weevils. These findings indicate that maize weevils facilitate the growth of A. flavus and aflatoxin production in corn by increasing surface area susceptible to fungal infection and increasing moisture content as a result of weevil metabolic activity. Weevil activity can have a profound effect on postharvest aflatoxin production even though little initial inoculum is present.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Thomas W. Phillips

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sitophilus zeamais	Stored grain
	Aspergillus flavus (plant/storage disease)	Stored grain