Artropodofauna associada a diferentes sistemas de cultivo de açaizeiro no nordeste paraense

Abstract

The açaí palm (Euterpe oleracea Mart.) is an important crop for Pará agribusiness for reaching new consumer markets in Brazil and in different countries. However, the growing commercial expansion that açaí has shown in recent years has reflected also in the significant increase in its acreage, which may result in the incidence of insect pests associated with these agroecosystems, thus requiring research actions focused on the alternative management and control of these biotic constraints. Simultaneously, new models of fruit crops have been tested successfully in the state of Pará, highlighting, among them, Agroforestry Systems (AFSs), aimed at increasing the number of crops (annual, permanent and / or forestry) implanted in an area. Among the benefits of AFSs stands out for its potential to maintain and multiply diversified beneficial entomofauna when compared to monocultures. Therefore, this study aimed to understand and compare the biodiversity of arthropods associated with the açaí palm in different cropping systems of the family farm in the northeast of Pará. It was analyzed three areas, two AFSs areas that had açaí palm as one of the main crops in the Marapanim town and an area of açaí monoculture, in the Igarapé-Açu town. In each area were implanted 45 Pitfall traps, which were equally distributed in three subareas: (a) near the açaí palm plants inside the plantation; (b) in the secondary forest around the crops; and (c) in the transition area between cultivation and secondary forest. Samples were collected into four distinct periods, one in the rainy season (CH), a transition period between the rainy and dry (CH / SE), one in the dry season (SE) and another collection corresponding to the transition period between dry and rainy (SE / CH). The insects biodiversity assessments were made in the soil (Pitfall traps). Arthropods (insect pests and natural enemies and spiders) collected in the field were stored in plastic containers (150 mL) containing 70% alcohol, and transported to the Entomology Laboratory of Embrapa Amazônia Oriental, where they were sorted, quantified and identified taxonomically . It was concluded that the periods of the year that most favor the presence of soil arthropods, regardless of crop fields, are the transition periods CH / SE and SE / CH. There was also a reduction in the population of ants in the three areas of secondary forest analyzed, and the gender Solenopsis (Westwood), Wasmannia (Forel) and Azteca (Forel) the most frequent in these areas. The area with açaí monoculture has a higher abundance of ants than the two AFSs analyzed. The spider family Lycosidae was found most frequently in this study, with the most abundant being Pacovosa gender. Agroforestry systems, if properly managed, form conducive environment for the arthropods species diversity like spiders and ants, which are admittedly efficient organisms in natural control of insect pests in crops. Transition periods grouped more individuals, followed by AFS area located in the Marapanim town, which represents the area most changed among the analyzed areas. Secondary forests are areas with smaller grouping of individuals and smaller gender diversity of ants and spiders.