Effects of bean plant density and its different cultivars on population of two spotted spider mite, Tetranychus urticae and onion thrips, Thrips tabaci in field condition

Common bean is cultivated for feeding in the whole world. The two-spotted spider mite, Tetranychus urticae Koch, and the onion thrips, Thrips tabaci Lindemann, are considered as the two important pests of bean and lots of pesticides are being used for their control. One of the most important strategies in integrated pest management programs is the cultural practice. In the present study the effects of cultivars and bean plant density has been taken into consideration to control these pests in a bean field in Boroujerd district, Lorestan province of Iran. This research was performed as per factorial in a completely randomized block design, with three cultivars (Akhtar, Derakhshan and 285) in five plant densities of 20, 30, 40, 50 and 60 plants per m2. Samplings were carried out weekly and in every sampling date, the number of each pest was recorded. Results showed that bean cultivars had significant impact on the number of eggs in spider mite and in total and 1st instar larval populations of onion thrips. The plant density also significantly affected populations of both the pests. Interactions between cultivar and plant density was not significant for both pests. Overall the highest and lowest population densities of the spider mite observed in the cultivar of Derakhshan with 60 plants density in every m2 and then cultivar of 258 with a density of 20 plants per m2 respectively. The lowest and highest total number of thrips was observed in Akhtar cultivar with 60 plants per m2 and then Akhtar cultivar with a density of 20 per m2, respectively. The results of the present study could be recommended in IPM program for bean fields.