oa Journal of the Entomological Society of Southern Africa - The inadequacy of egg counts as indicators of threshold levels for control of Heliothis armigera on cotton

Volume 44, Issue 2
  • ISSN : 0013-8789



In 1977-78 to 1979-80, eggs of H. armigera (H�bner) were collected regularly from cotton at two sites in the Transvaal and the percentage that hatched was determined. This varied greatly from week to week (extremes about 30 to 98%), mainly because of changes in parasitism. Other work showed that there was an equally variable incidence of mortality among young larvae. Thus, egg counts are poor indicators of numbers of mature larvae, and threshold levels based on such counts lead to excessive spray applications. It is suggested that counts of mature larvae should be used instead.

Loading full text...

Full text loading...


Article metrics loading...


This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error