Identification and Introduction to Thysanoptera from Bean Fields in some Regions of Markazi Province

Beans, Phaseolus vulgaris L., are one of the important cultivated crops in Iran. Markazi province with production, 17569 tons, on approximately 7837 ha, is one of most important center of the bean production in the country. The bean plants are attacked by various pests including Thysanoptera species. Thysanoptera are very small, slender with fringed wings insects which are widespread. Thrips reduce crop yield or its marketable value indirectly by vectoring viral plant diseases and directly Different studies were performed to investigate thrips fauna in different crop fields in Iran. But no study was done about identification of thrips species in the bean farms of Markazi province. This study as supplementary was established to investigate thrips faun in the bean fields of Markazi province and secondly to determine which species are more common than others.
The sampling were conducted on commercial bean farms (none chemical treatment) of five principle regions in Markazi (Central) province including Arak, Shazand, Farahan, Khomein and Aman-abad. The Markazi province with an area of 29,406 square kilometers with the climate is semi-arid, moderate and cold mountainous type. The diversity of climate leads to a varied rate of moisture and rain in different regions of the province. The specimens of Thysanoptera were collected from two bean farms (10 farms, each about 0.5 ha) in each five sampling sites every week. The sampling was performed during crop season from May to August, 2012-2013. In each farm, 10 bush bean spaced by at least 10 m from each other were randomly selected. The bush beans were shacked into the white tray and the fallen specimens immediately were collected by thin brush dipped in alcohol. The specimens of each species were counted and stored in Ethanol (80%). The specimens were classified based on body and antennae shape and color and shape of the end of the body and color design of wings., The microscopic slides were prepared and identification were confirmed by Mirab-balu, Assistant professor of Ilam University. All slides were preserved in Entomology laboratory, Department of Plant Protection, Sari University. According the data from 2012, percentage of frequency were calculated by the formula where n is number of the given species and N is total number of all collected species.
The results of this study indicate that the bean fields in different regions of Markazi province could harbor in sum 12 different species belonging to eight genera and three families. The only species belonged to suborder of Tubulifera was Haplothrips reuteri Karny, 1907 (Phlaeothripidae). The other collected species were belonged to suborder Terebrantia. These thrips species are including, Aeolothrips intermedius* Bagnall, 1934 from Aeolothripidae, Thrips atratus Haliday, 1836¡ T. tabaci Lindeman, 1889¡ T. trehernei Priesner, 1927, Microcephalothrips abdominalis* Crawford, 1910¡ Odontothrips confusus* Amyot & Serville, 1843 ¡ Scolothrips longicornis* Priesner 1926¡ Frankliniella intonsa Trybom, 1895¡ F. pallida* Uzel, 1895 ¡ F. occidentalis* Pergande, 1895 Tenothrips frici Uzel, 1895, all from Thripidae family. Among the collected species, six records are new for Markazi fauna which indicated by star (*).The species, onion thrips, Thrips tabaci has highest frequency (65.75 % of all collected species) and is widespread species in the bean farms of Markazi province. The thrips species belong to genus of Frankliniella comprising, F. pallida, F. occidentalis, with frequency, 10.9% and 9.49%, respectively are relatively other pest thrips in the bean fields. H. reuteri has very low frequency (4 %) in the bean farms. The rest species, M. abdominalis (0.07%), F. intonsa (0.22%), T. frici (0.54%), T. trehernei (0.54%) and T. atratus (0.049%) are occasional species. The all thrips species existed in bean fields during two crop season years (2012-2013) but the only, exception was Odontothrips onfusus that was collected during crop season in 2013 just from Shazand region. Two species, A. intermedius (Aeolothripidae) and S. longicornis (Thripidae) which reported for the first time for Markazi fauna are predator and they could feed on other herbivore thrips as well as T. tabaci. However, A. intermedius (8.08% frequency) is relatively more common in compare to the occasional species, S. longicornis (0.32% frequency).
The existence of 12 thrips species showed the relatively high species diversity in the bean field of Markazi province. Different reasons could explain the relatively high diversity. According the hypothesis that high plant diversity lead to high animal diversity, one reason could be because of the well diversity of other crop plants cultivated near to bean fields. Lack of chemical treatment also could be considered as the other reason. The onion thrips, Thrips tabaci, confirmed as most common thrips species in the bean fields of Markazi province. This species is very cosmopolitan and polyphage. It is already reported as a serious pest in other crops such as onion. Therefore, in pest management program, farmers should focus on this pest. Additionally, two thrips species, A. intermedius and S. longicornis reported for the first time as predator and also these have to consider in pests management in these areas.