ORIENTATION BY GRAVID AUSTRALIAN SHEEP BLOWFLIES, LUCILIA-CUPRINA (DIPTERA, CALLIPHORIDAE), TO FLEECE AND SYNTHETIC CHEMICAL ATTRACTANTS INLABORATORY BIOASSAYS

Gravid females of Lucilia cuprina (Wiedeman) in a laboratory cage orie ntated positively to samples of fleece. Newly-wetted fleece was signif icantly more attractive than dry fleece, an effect resulting from the action of water on the fleece and not just addition of water vapour to the volatile fleece kairomones. Fleece contaminated with serous exuda te, resulting from myiasis by L. cuprina, was much more attractive tha n wet, uncontaminated fleece from the same sheep. Kairomones from wett ed fleece consistently augmented the attractive effects of 2-mercapto- ethanol and indole in separate experiments, and of hydrogen sulphide ( released from saturated aqueous sodium sulphide solution) in one trial out of three, but not overall. It is suggested that volatile fleece k airomones play a part in eliciting orientation to sheep by gravid L. c uprina. Fleece kairomones may augment the efficacy of kairomones relea sed by putrefactive conditions in the fleece, which are known to predi spose sheep to fly strike. They may also provide an input which helps to retain L. cuprina populations in the sheep's peridomestic precinct.