Dispersal of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) in cabbage, cucumber, and sweet corn.

The dispersion capacity is fundamental to establish a biological control program with parasitoids. This information is used to determine the efficiency and the number of release points. Thus, the objective of this work was to determine the dispersion and to estimate the number of release points of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae), in sweet corn, cucumber and cabbage in the Ceara State. The experiments were carried out in areas of maize with four leaf pairs (V4) and eight leaves pair (V8), stacked and cabbage. Unviable eggs of an alternative host were distributed in concentric circles of radius 2.5; 5.0; 9.0 and 12.0 m. Mean dispersal distance in the V4 stage maize was 4.7 m with a dispersion area of 48.6 m(2), parasitism index of 18.4%, requiring 206 points/ha. In the V8 stage maize, the mean distance was 5.9 m, dispersion area of 60.3 m(2), mean parasitism index of 22.7% and 166 release points/ha. For the cucumber culture the mean distance was 6.0 m, dispersion area 62.2 m(2), mean parasitism index of 21.1% and 161 release points/ha. For cabbage the mean distance was 5.6 m, dispersion area of 56.8 m(2), mean parasitism index of 22.1% and 176 release points/ha.