Damage and Pest Status
Feeding and tunneling by stem borers can result in serious damage and crop losses. Damage is caused by the larvae, which at first feed on the young leaf funnels at the growing point and then later by tunneling into the stems. Apart from leaf damage, growing points may be killed, leading to stunting and deadhearts or to early senescence of plants. Stem tunneling may cause lodging, but also secondary and insidious effects, such as interference with translocation of metabolites and nutrients, resulting in malformation and loss of grain. There can also be a sharp increase in the incidence of stalk rot. Feeding in ears has been associated with fungal infection and elevated levels of mycotoxins.
In South Africa, crop loss assessments in cereal crops from B. fusca attack ranged from 10 to 100%. Although much of this was due to leaf damage in maize, the most severe loss was from stem-boring activity. In Lesotho, seasonal variation in maize yields due to B. fuscaranged from 0.4...