TOXICITY OF PHOSPHINE TO TROGODERMA VARIABILE BALLION (COLEOPTERA: DERMESTIDAE)

Abstract

AbstractThe susceptibility to phosphine of larvae and also whole cultures of the warehouse beetle, Trogoderma variabile, was investigated using strains collected from outbreaks of the pest in Australia. The LD99 for active larvae of 1 strain was found to be 6.7 ghm−3 at 25° C for a 20 h exposure. The LD99 for 3 strains of larvae in diapause was substantially greater than for the active larvae investigated, ranging from 24–59 ghm−3 under the same conditions and 4–6 ghm−3 after 120 h exposure. It took at least 42 d for the batches of larvae in diapause to reach end point mortality after exposure to phosphine. Active whole cultures of T. variabile were completely killed with an exposure of 43 ghm−3 at 20° C for 5 d, while whole cultures of larvae in diapause did not survive 25 ghm−3 under the same conditions. The minimum rate resulting in complete control under those conditions was not determined. The dosage mortality data obtained indicate that the dosages for phosphine currently recommended for stored product pest control in grain in Australia are adequate for control of T. variabile.