Relationship between Insect Pests of Maize and Aflatoxin Production-A.Review

Abstract

The objective of the review was to summarise the known information on insect pests of maize tha t have an association with aflatoxin contamination of the grain, thereby providing background information for the possible development of alternative control neasures for aflatoxin contamination of corn.
The review confirms that four insect species, Heliothis zea (Boddie), Spodoptera frugiperda (J.E. Smith), Ostrinia nubilalis (Hubner) and Sitophilus zeamais Motschuldky, significantly influence aflatoxin contamination of maize through pre-harvest damage to the maize kernels. Apart from causing direct damage to the kernels and thereby facilitating infection, it has been demonstrated that these insects act as vectors for the spores of both A spergillus flavus and A. parasiticus. Infection by A. flavus appears to be associated more with foliage feeding insects, whereas A. parasiticus infection appears to be associated with soil insects. Maize weevils (S. zeamais) appear to be the most important of these insects in relation to increasing both kernel infection and level of aflatoxin. contamination.
The level of infection by A. fluvus and level of aflatoxin production in maize kernels during preharvest is strongly influenced by lacation and climatic conditions. Relative resistance and susceptibility of different maize genotypes do not appear to have an influence on the amount of aflatoxin produced.
Insecticide application to the silks of developing ears can have a significant effect in reducing aflatoxin contamination through reduced insect damage. However, fungicide application to the silks does not produce any degree of control over either A. flavus infection or aflatoxin formation.