تعداد گونه

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.

The wheat thrips، Haplothrips tritici Kurd.، is an important pest of wheat crop، Triticum aestivum L.، in Ardabil region، northwestern Iran. Strip cropping of wheat and alfalfa، Medicago sativa L.، is a suitable strategy for improving the effectiveness of biocontrol agents of the wheat thrips. In this research، population density of the wheat thrips، and species richness and abundance of its predators were studied in the strip cropping of wheat and alfalfa (three-year old) and the monoculture of wheat during field surveys from 2010 to 2011. Sampling from each of two wheat cropping systems was conducted from the stem elongation until ripening stages. Number of the wheat thrips and predators per plant were recorded in each sample date. The population density of the wheat thrips in the strip cropping of wheat-alfalfa was significantly lower than that of monoculture of wheat. Five species of predators were recorded in the monoculture of wheat and 15 species of predators were recorded in the strip cropping of wheat-alfalfa. The Shannon diversity index for predators in the strip cropping of wheat-alfalfa was significantly higher than that for monoculture of wheat. The Morisita-Horn index between two wheat cropping systems was calculated 0. 842. The species richness and abundance of predators in the strip cropping of wheat-alfalfa were greater than the monoculture of wheat. Therefore، it can be concluded that the strip cropping of wheat-alfalfa increases the species diversity of the predators and reduces the population density of H. tritici. Quantifying the species richness and abundance of predators in the wheat fields is an important step in the management of the wheat thrips.