Dispersal of <i>Trichogramma platneri</i> Nagarkatti (Hym., Trichogrammatidae) from point‐source releases in an apple orchard in California

Abstract

Abstract Egg parasitoids of the genus Trichogramma are commonly released in inundative biological control programmes for lepidopteran pests in a range of cropping systems. In this study we evaluated the dispersal of Trichogramma platneri from a central release point in an apple orchard in relation to time and the number of parasitoids released. Dispersal was monitored by parasitism of codling moth eggs from an insectary culture—used as sentinel eggs. Higher release rates of T. platneri resulted in greater parasitism of sentinel eggs during the first 3 days, increasing from about 18% for a release rate of 5 400 to about 36% for a release rate of 32 400. T. platneri parasitized a greater percentage of sentinel eggs on the north side of the tree. Parasitism of sentinel eggs declined by 50% during the second 3 day period following release from a point source release in comparison to the first 3 day period. Parasitism of sentinel eggs declined from a mean of 62% at the point–source to less than 10% 14 m away during the first 3 days after release.