Insects collected in cultivate of maize in Brazil.

Corn (Zea mays L.), due to its productive potential, chemical composition and nutritional value, is one of the most important cultivated and consumed cereals in the world. For this reason, a population survey of insects was conducted in the city of Itumbiara, Goias State, Brazil. During the growing season in 2000. The most collected species were: Doru luteipes (Dermaptera: Forficulidae), Gryon gallardoi (Brethes) (Hymenoptera: Scelioidae), Helicoverpa zea (Lepidoptera: Noctuidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae). These results are important because they contribute to the knowledge of insect species that occur in corn crop in the state of Goias, Brazil.


Keywords: parasitoids, preadators, biological controle, insects pest Goias.

T he objective of this work was to carry out on population survey of insects that occur in the corn crop, also verifying the influence of treatments on the insect population (pests and natural enemies).

MAT ERIAL AND MÉT HODOS
T he experiment was carried out at Santa Maria farm in Itumbiara, Goiás, Brazil. T he study was conducted on an area of one hectare. T his hectare was divided into 7 plots, each containing an area of 44x20m. T he collections were weekly from January to February 2001. In each treatment, eight ears of corn were randomly collected and individualized in plastic bags, taken to the laboratory and placed in a cold chamber for 24 hours to obtain the insects. T he dead individuals were removed with the help of tweezers that were counted and identified later.
T o obtain the parasitoids, Hemiptera eggs and Diptera pupae were then placed in the chamber. T he obtained egg mass was placed in a glass jar and the pupae individualized in gelatin capsules and kept until the emergence of the parasitoids and / or adults Hemiptera and Diptera.

RESULT S AND DISCUSSION
From January to February 2000, 280 ears of corn were collected, from which 381 insects were obtained. It was observed that 53.6% of these ears were damaged, probably due to the attack in the pests.
T able 1 presents the insects collected iduring the 2000 harvest, emphasizing agricultural pests and natural enemies such as predators and parasitoids. T he most frequent natural enemies collected were the predatory species Doru luteipes (Dermaptera: Forficulidae) and the parasitoid Gryon gallardoi (Hymenoptera: Scelioidae).
T he most collected agricultural pests were: Helicoverpa zea (Lepidoptera: Noctuidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae). H. zea and S. frugiperda can be considered the main corn pests in the region. Doru luteipes has proven to be an efficient pest predator, many of them harmful (CRUZ & OLIVEIRA, 1997). One insect has been shown to have great potential in the biological control of two major maize pests, such as H. zea and S. frugiperda (CRUZ et al., 1997).
T he insect is found in the field throughout the year, especially in the early stages of corn cultivation (CRUZ et al., 1997).
Gryon gallardoi belongs to the Scelionidae family. It is a parasitoid of eggs of the family Hemiptera Coreidae (LOIACONO, 1980). T his species is found in Argentina (Buenos Aires) and Brazil (Porto Alegre-Rio Grande do Sul) (LOIACONO, 1980).
T he insect H. zea, known as the corn cob caterpillar or tomato borer, attacks corn, cotton, tomato, sorghum, onion, garlic, cucurbit, solanaceae and common bean.
Important pests of maize, especially sweet corn, destroy the ear grains and tomato fruits (ZUCCHI et al., 1993). It causes damage to corn crop, feeding on the style and stigma of the plant, preventing fertilization and consequently grain formation (CRUZ et al., 1995).
T he results obtained in this study allow to extend the geographic distribution of insects collected in corn crop in the Brazilian territory. T hese results are important because they contribute to the knowledge of insect species that occur in corn crop in the state of Goiás, Brazil.