J. Bio. & Env. Sci

Increasing crop diversity via intercropping is a simple and effective strategy for reducing pest density. A field experiment was conducted at Research Farm of Tabriz University, Tabriz, Iran during 2014. The experiment was arranged as factorial, based on randomized complete block design with three replications. The first factor was four cropping systems including monocropping of faba bean and three row intercropping of faba bean with dragonhead and the second factor was three levels of fertilizers as 100% chemical fertilizer, 50% chemical fertilizer + biofertilizer and biofertilizer. The results indicated that the population density of black bean aphid (Aphis fabae) was affected by cropping pattern and fertilizer. Also at flowering stage the interaction effect of cropping pattern × fertilizer on population density of Aphis fabae was significant. The faba bean monocropping had the greatest mean number of Aphis fabae for all fertilizer treatments. Also the lowest density of Aphis fabae was observed at 1 faba bean 1 dragonhead cropping patterns with application of biofertilizer. The population densities of Hippodamia variegata Goeze and Coccinella septempunctata L. were the lowest and greatest in faba bean monocropping and 1 faba bean 1 dragonhead intercropping, respectively. Generally by application of biofertilizer, the effect of cropping pattern on reduction of Aphis fabae density increased. *Corresponding Author: Solmaz Azimi  azimi@azaruniv.edu Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220-6663 (Print) 2222-3045 (Online) Vol. 6, No. 3, p. 380-388, 2015 http://www.innspub.net J. Bio. & Env. Sci. 2015 381 | Azimi and Amin