Natural Occurrence and Ecology of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) in Cotton Plantations with Insecticides Spraying in Minas Gerais State, Brazil

Pest damage is one of the greatest problems in cotton production in the world. The objective of this study was to assess the natural occurrence, parasitism rate, number of adults ofTrichogramma emerged and coexistence with predators species in cotton plantations with insecticide spraying in Brazil. Parasitoids were collected in two areas of two-hectares each with the Dp 4049 and Delta Opal cotton varieties, using 12.0 x 2.5 cm pieces of white cards with an average of 3.000 Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs each. The predation percentage of A. kuehniella eggs in the field and parasitism occurrence was estimated based on the cards with eggs of this prey brought from the field. All parasitoids obtained were identified as Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae). The predators collected were identified as belonging to the families Chrysopidae (Neuroptera), Coccinelidae (Coleoptera) and Sirphidae (Diptera). The average number of eggs parasitized per cardboard, during the cycle of this culture was 16.34 ± 5.1 in the area with Dp-4049 and 23.38 ± 4.3 in that with Delta opal. The predation average during the cycle of this culture was 42.58 ± 3.8 e 35.58 ± 2.9% in these areas, respectively. It is necessary to preserve and to increase the performance of T. pretiosum in cotton plantations