Carbon dioxide fumigation of <i>Thrips tabaci</i> in export onions

Abstract

As an alternative to chemical pesticides elevated carbon dioxide atmospheres were examined as a method for controlling thrips on export onions A replicated gas delivery system was used to deliver a constant supply of various concentrations of carbon dioxide (CO₂) to thripsinfested onions within sealable bags Six CO₂ treatments an air control and 15 30 45 60 and 100 CO₂ (all in balance air) were applied for 6 12 24 48 and 72 h Mortality was 100 at CO₂ concentrations of 30 or more after at least 24 h However the control treatments also had a high level of mortality and although there were significant differences between the control treatment and the CO₂ treatments these differences were not large