CODLING MOTH: A PILOT PROGRAM OF CONTROL BY STERILE INSECT RELEASE IN BRITISH COLUMBIA

Abstract Codling moth, Cydia pomonella (L.), control by sterile insect release (SIR) was assessed in 320–526 ha of apples and pears in the Similkameen Valley, B.C., from 1976 to 1978. In preparation for SIR, the moth population was first reduced to low numbers by removal of neglected trees in 1972 and by chemical sprays in 1975. Sterile (35 krad) male and female moths were released in each orchard 2 or 3 times weekly from 1 May until early September. A total of 23,600 sterile moths/ha was released in 1976, 36,500 in 1977, and 31,800 in 1978. Populations of sterile (marked) and wild moths were monitored by sex pheromone traps, and damage was assessed by fruit examination at harvest. Control was very good except for a few orchards in which overwintered populations were too high to achieve adequate overflooding with sterile moths. Damage exceeded the economic threshold (0.5%) in only 1 of 86 treated orchards in 1976, in 6 of 193 orchards in 1977, and in 0 of 157 orchards in 1978. Results in 32 orchards showed that when wild populations are brought close to extinction all codling moth control measures can be omitted for 2 or more years depending on degree of orchard isolation. Omission of codling moth sprays from 1976 to 1978 did not result in any important change in population levels of other apple pests. Cost of control by SIR was ca. $225/ha per year vs. ca. $95 for chemical control.