, .. • • PHYSIOLOGICAL AND CHEMICAL ECOLOGY Toxicity and Repellency of Semiocbemicals Extracted from a Dolicboderine Ant (Hymenoptera: Formicidae) to the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) MARY L. CORNELIUS,! J. KENNETH GRACE, 1 PAUL W. FORD, 2 AND BRADLEY S. DAVIDSON 2 Environ. Entomol. 24(5): 1263-1269 (1995) ABSTRA€T The anal gland secretions of ants in the subfamily Dolichoderinae contain ter- penoids that are !mown to have insecticidal properties. The repellency and toxicity of whole- · body extracts and chemical fractions of such extracts from the dolichoderine ant Ochetellus glaber (Mayr) to Coptotermes fornwsanus Shiraki (Isoptera: Rhinotermitidae) were examined. Extract-treated sand caused significant termite mortality in a direct-exposure assay. Termites were also repelled by extract-treated sand and the chemical repellency lasted for at least one month in treated ·sand. The principal repellent components of 0. glaber secretions were de- termined to be cis,trans-and trans,cis-isomers of dolichodial in a 3:1 ratio. KEY WORDS Coptotermes fornwsanus, Ochetellus glaber, monoterpenes SUBTERRANEAN TERMITES ARE the greatest single cause of damage to wooden structures in the Unit- ed States. It is estimated that damage caused by subterranean termites reaches $1-$2 billion an- nually (Hedges 1992). In Hawaii, .estimated costs to control infestations and repair damage caused by the Formosan subterranean termite, Coptoter- mes forrrwsanus Shiraki, exceed $60 million each year (Yates and Tamashiro 1990). Formosan sub- terranean termites are also serious pests in the southern gulf states (Su and Scheffrahn 1986), and they have recently been discovered in California (Atkinson et al. 1993). There has been great interest in the develop- ment of naturally produced chemicals as alterna- tives to synthetic insecticides for use in pest con- trol programs. The search for natural products has focused primarily on plant allelochemicals such as azadirachtin (Schmutterer 1990, Scheffrahn 1991, Grace and Yates 1992); however, insects also pro- duce an arsenal of chemical weapons that could be potentially useful in pest control (Blum 1981). For example, ants produce compounds that repel other ant species (Scheffrahn et al. 1984, Andersen et al. 1991). Allelochemicals were effective in disrupting foraging by 2 ant species, Linepithema humile (Mayr) (Shorey et al. 1992) and Formica aerata (Francoeur) (Shorey et al. 1993). · Although certain ant-produced chemicals are known to be toxic to termites in topical applica- tions (Clement et al. 1986, 1988; Escoubas and Blum 1990), little attention has been given to 1 Department of Entomology, University of Hawaii, Honolulu, HI 96822. 2 Department of Chemistry, University of Hawaii, Honolulu, ·HI 96822. their potential as tools for the management of ter- mite populations. The anal gland secretions of ants in the subfamily Dolichoderinae contain ter- penoids that are known to have insecticidal prop- erties (Cavill and Houghton 1974, Cavill et al. 1976, 1982). We examined the toxicity and repel- lency of secretions of the dolichoderine ant Och- etellus glaber (Mayr), formerly Iridomyrmex, in treated sand. In previous research, we found that termites were prevented from tunneling through sand treat- ed with 0. glaber extracts in an indirect-exposure tunneling assay (Cornelius and Grace 1994). In iliis assay, termites were placed in a container filled with untreated sand and were allowed access to a tunneling arena filled with extract-treated sand. Because termites were repelled by contact with · treated sand, they generally remained in the con- tainer with untreated sand and did not penetrate ilirough the treated sand in the arena. Therefore, termite exposure to treated sand was limited and there were no effects on termite mortality in this indirect-exposure assay. We examined the effect of extract-treated sand on termite mortality in a di- rect-exposure assay where termites were confined to containers with· treated sand for a continuous exposure. We also conducted experiments to de- termine the longevity of the repellent effect of the extract on termite tunneling behavior in an indi- rect-exposure bioassay. The principal repellent components of 0. glaber secretions were isolated and the identities of the active components as de- termined using behavioral assays were confirmed by gas chromatography/mass spectrometry and nu- clear magnetic resonance techniques. 0046"225X/95/1263-1269$02.00/0 © 1995 Entomological Society of America