Population Diversity and Abundance of Some Natural Enemy and Herbivorous Insect Families under Soybean (Glycine max) and Corn (Zea mays)Intercropping System in Farm Conditions

To study the effect of soybean and corn intercropping system on diversity and abundance in some natural enemy and herbivorous insect families under farm conditions, an experiment was carried out in a randomized complete blocks design (RCBD) with five treatments and four replications in2011-2012. The treatments included 00:100 soybean pure crop, 100:00 corn pure crop as well as 50:50, 25:75 and 75:25 corn: soybean combinations. Considering their establishment sites (on soil or plants), different sampling methods such as pitfall trap, sieving, together with yellow and blue sticky cards, were used for collecting the insects. Sampling was conducted in five periods in fortnight intervals.Totally5,292 insects, belonging to eight orders and thirteen families, were collected. Results showed that the population in some of these natural enemy and herbivorous insect families is significantly influenced by intercropping system, so that the maximum number of natural enemy insects and the minimum number of herbivorous insects were observed in 50:50 (corn: soybean) mixed treatment. However, minimum natural enemy insects were seen in corn pure crop treatment, and maximum herbivorous insects were observedin corn and soybean pure crops, respectively. Ultimately, 25:75 (corn: soybean) treatment had the maximum yield in soybean, while 75:25 (corn: soybean) treatment having the maximum yield in corn.