FREEZE-DRIED ARTIFICIAL DIET-BASED TECHNIQUE FOR SCREENING PLANT-EXTRACTS AGAINST EPIPHYAS-POSTVITTANA (LEPIDOPTERA, TORTRICIDAE)

A bioassay method based on freeze-dried artificial diet for assessing feeding and contact toxicity in light brown apple moth, Epiphyas postv ittana Walker, larvae is described. Diet disks were vacuum freeze-drie d. Organic solvent extracts were added to the disk (120 mu l), vacuum evaporated for 3 h, and reconstituted with distilled water before addi ng the neonate larvae (40 per replicate). This technique took 42 min p er extract to set up and evaluate. Results for a range of foliage extr acts of New Zealand gymnosperms are discussed. Ability to test the act ivity of extracts dissolved in volatile organic solvents was seen as a major advantage of this technique.