Alfalfa Planting Beside Sugarcane and its Effect on Biodiversity and Sugarcane Stem Borer's Damage

The relationship between diversity of plant and arthropod species was studied in sugarcane fields in Ahwaz، Southern Iran during 1998 to 2001. Strips of alfalfa were planted along the short side of each 250 x 1000 m block. Arthropod species were collected monthly for 24-48 hours using Malaise and pitfall traps which were located inside the sugarcane blocks. One Malaise trap at 3 meters and two pitfall traps at 2 and 4m from the margin were established in each sugarcane block. The diversity (species richness) and evenness (relative abundances) of arthropod species were measured by Shannon indices. The percentages of stems attacked by the two stem borers، Sesamia cretica and S. nonagroides (Lepidoptera: Noctuidae) were also recorded on each sampling day. Data was compared for sugarcane blocks with and without alfalfa strips. Results indicated that species richnesswas higher and the percentage of infection to stem borers was lower significantly in sugarcane blocks with strips of alfalfa than without.