Understorey influence on leafroller populations in Hawkes Bay organic apple orchards

Abstract

Leafrollers (Tortricidae) were collected from apple foliage and understorey vegetation in six commercial organic apple orchards in Hawkes Bay over one season Assessments were made of plant species present in the understorey at the time of collection All leafroller larvae were reared to adults on artificial diet to identify leafroller species and parasitoids Nearly half (47) of all leafrollers collected in these orchards were located in the understorey highlighting the importance of understorey and its management for the control of leafroller Dock clover and dandeliontype plants contributed 25 to the overall understorey yet hosted 75 of the leafrollers collected from the understorey Dolichogenidea sp was the most abundant parasitoid (79) attacking leafrollers found amongst the apple foliage whereas Glyptapanteles demeter was dominant in the understorey (61) Generally the number of leafrollers in an orchard was proportional to the abundance of broadleaf weeds and inversely proportional to parasitism