LABORATORY EVALUATION OF MINERAL-OILS FOR CONTROL OF CODLING MOTH (LEPIDOPTERA, TORTRICIDAE)

Horticultural mineral oils are ovicides against the codling moth, Cydi a pomonella (L.), when applied directly to the eggs. The susceptibilit y of eggs to the oil varied depending on the substrate on which eggs w ere laid. On an inert surface such as waxed paper, young eggs were thr ee times as susceptible as eggs laid on apples. Susceptibility to oil changed little throughout the incubation period except just before hat ch when egg susceptibility dropped markedly. There was no difference i n ovicidal activity among three commercial horticultural mineral oils. Eggs laid on top of oil residue were not affected at labeled rates. T opical treatment of neonates caused no mortality at concentrations equ ivalent to field rates. Oil residue on the fruit surface did not inhib it neonates from entering fruit tissue. Moths suffered no mortality fr om direct oil treatments. Although the total number of eggs deposited by oil-treated and untreated moths was the same (107.5 and 90.3 eggs p er female, respectively), treated moths discharged their egg supply at a faster rate. Female moths avoided fruit surface with oil residue fo r oviposition. Results suggest that dilute applications of 1% horticul tural mineral oil may not be adequate for reducing codling moth egg ha tch in the field.