EVALUATION OF CREOSOTE FORTIFIED WITH SYNTHETIC PYRETHROIDS AS WOOD PRESERVATIVES FOR USE IN THE SEA .1. EFFICACY AGAINST MARINE WOOD-BORING MOLLUSKS AND CRUSTACEANS

Scots pine wood samples were treated with creosote, CCA plus creosote, creosote fortified with different concentrations of the synthetic pyr ethroids permethrin, cypermethrin and deltamethrin, and these syntheti c pyrethroids in white spirit. Replicate treated and untreated samples were exposed in the sea for 59 months at three tropical sites in Aust ralia and Papua New Guinea, and for 44 months at a fourth site in Sing apore where populations of teredinids, pholads, limnoriids and sphaero matids were known to be present. Untreated samples were destroyed by m arine borers after ca. 2 years. Samples treated with synthetic pyrethr oids in white spirit were very severely damaged or destroyed by the en d of the trial, while the samples treated with creosote fortified with synthetic pyrethroids ranged from very slight to moderate attack. Ter edinid and limnoriid infestation of samples treated with all the creos ote-containing preservatives was almost totally absent at all sites; p holad and sphaeromatid damage was very slight to moderate. The most pr omising combination treatment against pholads and sphaeromatids was cr eosote fortified with deltamethrin.