EGG PARASITISM OF THE BRAZILIAN APPLE LEAFROLLER IN FUNCTION OF THE NUMBER OF Trichogramma pretiosum RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE) RELEASED

Abstract

The objective of this work was to evaluate the egg parasitism of Bonagota salubricola (=cranaodes) (Meyrick) (Lepidoptera: Tortricidae) in function of the number of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) strain bonagota released in apple orchards. An experiment was implanted in the experimental design entirely randomized, in three consecutive stages, in adult commercial orchard, during 2004/05 season in Fraiburgo, SC Brazil, split in five experimental units of 1.0 ha, which received one of the following treatments: absence (control), liberation of 50.000, 100.000, 150.000 and 200.000 parasitoids ha^-1, fragmented in 50 points, of which two were considered evaluation points. Starting from these points cages were installed at 1, 4.5 and 10 m, in the height of 1.50 m, that received adults of B. salubricola. The parasitoids were liberated 48 h after B. salubricola infestation in the cages, using paper cards with eggs of Sitotroga cerealella (Oliv.) (Lepidoptera: Gelechiidae) parasitized close to the emergency. The leaves containing postures were collected, eight, eleven and five days after the liberation of the parasitoids for parasitism evaluation 10 days after. The parasitism of T. pretiosum was adjusted to a quadratic function, indicating positive relationship between the parasitism and the density of the parasitoids up to 150.000 individuals per hectare, decreasing from this level on, evidencing to be the closest proportion of the ideal.