DISTRIBUTION AND NATURAL PARASITISM OF SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE) EGGS AT DIFFERENT PHENOLOGICAL STAGES OF CORN

Abstract

The oviposition behavior of Spodoptera frugiperda (J. E. Smith) and natural parasitism of this pest by Trichogramma spp. at different phenological stages of corn were evaluated under field conditions. The distribution of S. frugiperda eggs varied according to the phenological stage of the corn. The preferred site for oviposition was the lower region of the plant and the abaxial leaf surface during the early development stages of the crop (4-6 leaves), changing to the middle and upper regions of the plant and the adaxial leaf surface at subsequent stages (8-10 and 12-14 leaves). A larger number of egg masses, and, therefore, of eggs was collected at the 4-6 and 8-10 leaf stages compared to plants in the 12-14 leaf stages. Natural parasitism was low, with a maximum of 2.21% eggs parasitized, especially on the lower and middle parts of the plant. The distribution and degree of parasitism by Trichogramma spp. on different regions of the plant were independent of the developmental stage of the crop. Trichogramma pretiosum Riley was the most frequent parasitoid, found in 93.79% of the parasitized eggs, followed by Trichogramma atopovirilia Oltman & Platner, with 2.07%.