REPELLENCY OF VARIOUS OILS AND PINE OIL CONSTITUENTS TO HOUSE-FLIES (DIPTERA, MUSCIDAE)

Comparative repellency of pine, mineral, motor, and silicon oil to hou se flies, Musca domestica L., was tested. In binary choice bioassays w ith flies feeding on 20 mu l of watery honey solutions mixed with (tre atment) or without (control) 10 mu l of one of the oils under investig ation, only pine oil completely suppressed feeding and remained inhibi tory even after 24 h. Approaching pine oil-treated honey solution, 95% of flies were repelled at a distance >6 mm from the source. Analysis of pine oil volatiles by coupled gas chromatographic-electroantennogra phic detection (CC-EAD) analysis revealed 5 antennally active compound s, 4 of which were identified by coupled GC-mass spectrometry as myrce ne, p-cymene, gamma-terpinene, and (+/-)-linalool. Treatment of honey solution with pine oil, the 4 compounds singly, or in quaternary combi nation at 10 mu l each, equally and significantly reduced the number o f feeding flies compared with untreated honey solution. At an amount o f 1 mu l, only the linalool treatment inhibited feeding. In binary cho ice experiments hath feeding and oviposition were significantly reduce d on linalool-treated sources. Because By maggots naturally develop in and rely on microbe-rich organic sources, gravid females may perceive and avoid potential oviposition sites that are rich in antimicrobial compounds such as linalool.