175 Habituation in Termite Orientation Response to Fungal Semiochemicals by J.K. Grace1 ABSTRACT Evidence is presented of behavioral habituation by Reticuli- termes flavipes workers to a dichloromethane extract of wood decayed by G/oeophyl/um trabeum. In a series of two-choice orientation assays, termite response to paper disks treated with G. trabeum extract decreased as the length of the exposure period increased. Subsequent assays indicated that this response decrement was not due to loss of the semiochemicals. Termites conditioned by prior exposure to the fungal extract did not demon- strate a positive orientation response. INTRODUCTION Wood infected by the brown-rot decay fungus Gloeophyllum trabeum (Pers. ex Fr.) Murr. (Basidiomycetes: Polyporaceae) contains (Z,Z,E)-3,6,8-dodecatrien-1-ol (Matsumura et al. 1969) and other semiochemicals (Ritter & Coenen-Saraber 1969) that elicit positive orientation (including trail-following) and arrest- ment responses in Reticulitermes spp. (lsoptera: Rhinotermi- tidae) ( Esenther et a!. 1961; Allen et a/. 1964). Observations of these positive behavioral responses to fungal extracts inspired the bait-block method of termite control (Esenther & Coppel 1964), and subsequent investigations of toxic analogues of the dodecatrienol (Carvalho & Prestwich 1984) and other potential bait toxicants. In this paper, I report evidence of behavioral habituation in Re- ticulitermes flavipes (Kollar) workers as the resultofexposure to a dichloromethane extract of G. trabeum. Habituation, the simplest form of learning, refers to a decrease in response to a stimulus occurring as the result of repeated or continuous expo- 1Faculty of Forestry, University of Toronto, Toronto, Ontario, M5S 1A 1, CANADA