Effect of intercropping systems of green bean and clover on biodiversity of natural enemies of Thrips tabaci Lindeman

In this research, the influence of intercropping systems (including three, six and nine rows of green bean, Phaseolous vulgaris L. with alternate three rows of clover, Trifolium resupinatum L.) and monoculture of green bean on biodiversity of the onion thrips, Thrips tabaci Lindeman and the proportion of predators/prey density were studied in an experimental field in the Ardabil during 2015 and 2016 years. In this study, 21 species of onion thrips predator were collected and identified that among them, the predator species Aeolothrips intermedius Bagnalland and Orius niger (Wolff) had the highest relative abundance in each of cropping systems. The Shannon diversity index (H) in each of the three intercrops was significantly greater than in green bean monoculture. The values of Morisita–Horn index (CMH) between green bean monoculture and each of the three intercrops (CMH ≤ 0.85) were lower in comparison with the values of this index among the three intercrops (CMH ≥ 0.94). In two years, the proportion of predators/prey and the density of the onion thrips predators especially two dominant species A. intermedius ‌and O. niger in each of the three intercrops were significantly higher than in green bean monoculture. Therefore, it can be concluded that strip-intercropping of green bean with clover caused higher biodiversity of the onion thrips predators and reduced the density of T. tabaci. Application of the mentioned strip-intercropping systems in the green bean fields as one of the important components in the integrated management of the onion thrips is recommended.