LABORATORY ASSESSMENT OF THE EFFICACY OF PHOSPHINE AND METHYL-BROMIDE FUMIGATION AGAINST ALL LIFE STAGES OF LIPOSCELIS-ENTOMOPHILUS (ENDERLEIN)

Liposcelis entomophilus is common and often very abundant in cereal stores in hot, humid areas, heavy infestations in South-East Asia being associated with phosphine fumigation. Tolerance of all life stages to phosphine fumigation was investigated under tropical storage conditions. Eggs were most tolerant and required a concentration of 1.7 mg 1-1 for 5 days to kill 99% of the eggs, but this gas concentration would prove difficult to attain in a typical fumigation under gas-tight sheets. When L. entomophilus was exposed to methyl bromide over a range of concentration X time (CT) products at 27-degrees-C and 30% relative humidity, all life stages were controlled at 50 mg l-1 h-1. Higher CT products would be required to kill the most tolerant life stages of common stored-product pests, such as Tribolium castaneum but the CT products normally attained using gas-tight sheet fumigations are sufficient to kill L. entomophilus.