New Zealand lessons may aid efforts to control light brown apple moth in California

T recent discovery of light brown apple moth, a leafroller, in California may affect the management of fruit crops, and because it is a quarantine pest in some markets, the discovery has already had implications for domestic and export trade in produce and nursery stock. In New Zealand, light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), was first reported in 1891 (Hudson 1928). It became a major pest, primarily of pome fruit (apples and pears) and berry fruit, and a minor pest of grapes, citrus, stone fruit and kiwi fruit. The number of acres planted to pome and berry fruit — the crops most affected by light brown apple moth — is similar in New Zealand and California (table 1). New Zealand went through a phase from the 1960s to 1980s when light brown apple moth caused major fruit damage; in apple crops this averaged from 8% to 26% and as high as 48% (Collyer and van Geldermalsen 1975). Control programs were based on frequent applications of broad-spectrum insecticides. This led to the development of resistance to organochlorines in the early 1960s (Collyer and van Geldermalsen 1975) and organophosphates by the early 1980s (Suckling et al. 1984; Suckling and Khoo 1990). Over the last two decades, the pest status of light brown apple moth in New Zealand apples has shifted significantly. Damage has decreased to typically less than 2% in unsprayed trees (fig. 1). The decline in fruit damage is associated with lower leafroller density, which in turn is attributed to two key factors: (1) the introduction in the 1960s and subsequent spread of parasitoids tABlE 1. Planted area of light brown apple moth fruit-crop hosts