Behavioural, electrophysical and chemical studies on naturally occurring termite repellents effective against Reticulitermes Lucifugus Santonensis (Feytaud) (isoptera: Rhinotesmitidae: heterotermitinae)

Floyd, Margaret Anne (1975) Behavioural, electrophysical and chemical studies on naturally occurring termite repellents effective against Reticulitermes Lucifugus Santonensis (Feytaud) (isoptera: Rhinotesmitidae: heterotermitinae). University of Southampton, Doctoral Thesis.

Abstract

Many woods have been reported to be resistant to termite, attack an several of these timbers were found. to be repellent to the European subterranean termite Reticulitermes lucifugus santonensis'(Feytaud) and.to the dampwood termite Zootermopsis nevadensis (Hagen). Teak (Tectona grandis) and afzelia (Afzelia bipedensis were the most repellent. A series of quinones from other hardwoods was tested, for biological activity by electroantennography and for repellency by behavioural bioassay. All quinones which gave an electroantennogram response were repellent to R.l.santonensis. All of the substituted anthraquinones tested ad a napthaquinone, lapachol, were repellent. Other napthaquinones and benzoquinones were inactive. Theknown constituents of Afzelia spp,' kaempferol, afzelin and epiafzelechin were tested but were not repellent. The hearwood of Afzelia bipedensis was extracted, with hexane and;methylene chloride and fractionated, by chromatography. The biological activity was followed timbers in behavioural bioassays. chemical constituents of teak was Tectoquinone, one of the principal) shown to be repellent,throughout the fractionation by electroantennography and behavioural bioassay. Compounds from Afzelia,which were separated and identified by linked gas chromatography-mass spectroscopy included methyl and ethyl esters of straight chain saturated acids, and monoterpenoids, none of which were repellent to R.l.santonensis. The repellent fraction was composed of polar molecules with high molecular weight. The technique of electroantennography was used extensively to evaluate repellents,, using R.l.santonensis. Thirty-eight monoterpenes were investigated and all the repellent monoterpenes gave a good electrosntennogram response and compounds which did not give an electroantennogram response were not repellent. There was some evidence of a correlation, between three-dimensional molecular, structure and repellency. However, there was no evidence that biological activity was influenced by molecular vibrations in the far infra-red region (90-500 =nm-1)as might be expected from Wright's theory of olfaction. Electroantennography was also used in,conjunction with behavioural bioassay to evaluate compounds which stimulated trail following behaviour in R.1.santonensis. The technique was developed to investigate biologically active compounds in other insects from three different orders:' Isoptera, Hymenoptera and Coleoptera.

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