Susceptibility of western flower thrips, Frankliniella occidentalis (Pergande) to fumigation with methyl bromide

All life stages of the western flower thrips (Frankliniella occidentalis Pergande) were tested for their response to the fumigant methyl bromide and dose response curves were established. Pseudo-pupae were the most tolerant stage with a calculated LD99 of 53.1 mg litre“¹ h at 15^oC with a gas concentration of 13.5 mg litre”¹, but no survivors were found in any test above a concentration time product of 40 mg litre“¹ h. Standard 4 h fumigations achieving a CTP of 54 mg litre”¹ h that are used to control other pests are therefore likely to give very high levels of control of western flower thrips.