Pecan growth under different soil preparation and hole sizes: coleopterans as bioindicators

The study aimed to evaluate the effects of different soil preparation and hole sizes in an orchard of Carya illinoinensis pecan (Wangenh.) K. Koch (Juglandaceae) by the Order Coleoptera fauna. A pecan orchard was established in spacing 7 m x 7 m, in Santa Maria, Rio Grande do Sul State, Brazil in randomized block design, with five blocks and four treatments, using: small pit 20 m x 60 cm (Cp); more harrowing subsoiler and small pit (Scp); rotary hoe and small pit (Ecp); and large pit 40 m x 60 cm (Cg). From March 2014 to November 2015, eight samples were taken from Coleoptera fauna, one per season, with four pitfall traps distributed in each treatment and the surrounding area, totaling 100 samples per collection. The Ecp treatment had the lowest diversity values and evenness for Coleoptera fauna, while the Cp and Cg treatments presented the highest indices. The species Diloboderus abderus (Sturm) was as very common. It was concluded that Cg treatment does not interfere with coleopteran and promotes the highest growth in diameter of pecan plants