چكيده فارسي :
به منظور مطالعه تنوع زيستي بال ريشكداران در چين هاي مختلف يونجه، نمونه برداري ها به طور هفتگي از ابتداي فروردين ماه تا اواخر شهريور سال 1396 از مزارع يونجه يكساله، سه ساله و چهارساله شهرستان ايوان (استان ايلام) به عمل آمد. نمونه ها با استفاده از روش تكاندن گياه يونجه درون سيني سفيد جمع آوري و سپس به داخل شيشه هاي محتوي الكل 75 درصد منتقل شدند. پس از انتقال به آزمايشگاه، از آنها اسلايدهاي ميكروسكوپي تهيه و در سطح گونه شناسايي شدند. در اين تحقيق، 10 گونه متعلق به 6 جنس و چهار خانواده ي مختلف از مزارع يونجه جمع آوري و شناسايي گرديد. در بين گونه هاي جمع آوري شده، بيشترين درصد فراواني مربوط به Thrips tabaci با فراواني 59/12 درصد و كمترين فراواني مربوط به Tenothrips frici با فراواني 0/24 درصد به دست آمد. تنوع زيستي بال ريشكداران در چين هاي مختلف رشدي يونجه، با استفاده از شاخص هاي تنوع شانون-وينر، سيمپسون، غناي مارگالف و يكنواختي شانون محاسبه شدند. با توجه به محاسبات انجام شده، ميزان شاخصهاي تنوع شانون-وينر، سيمپسون، غناي مارگالف و يكنواختي شانون در مزرعه يونجه يكساله به ترتيب 2.71 ± 0.04, 0.92 ± 0.04, 3.49 ± 0.02 و 0.89 ± 0.01، در مزرعه يونجه سه ساله به ترتيب 2.26 ± 0.09, 0.88 ± 0.009, 2.58 ± 0.18 و در مزرعه يونجه چهارساله به ترتيب 2.09 ± 0.14, 0.85 ± 0.01, 2.31 ± 0.29 و 0.92 ± 0.01 به دست آمد. نتايج نشان داد كه تنوع شانون-وينر، سيمپسون و غناي مارگالف بال ريشكداران در مزرعه يكساله به طور معني داري بيشتر از مزارع سه و چهارساله بود، اما شاخص يكنواختي شانون مزرعه يونجه چهارساله بيشتر از مزارع يكساله و سه ساله بود ولي اين تفاوت معني دار نبود. به طور كلي نتايج نشان داد كه تنوع زيستي بال ريشكداران در مزارع يونجه يكساله بيشتر بوده و با افزايش سن گياه ميزان تنوع زيستي كاهش مييابد، از طرف ديگر در مزارع يكساله به دليل متراكم بودن گياه يونجه نسبت به مزارع سه و چهار ساله، محيط مناسبي براي حشرات به وجود مي آورد. در واقع زيستگاه مناسب عاملي براي افزايش تنوع زيستي حشرات محسوب مي شود.
چكيده لاتين :
Introduction: Alfalfa (Medicago sativa L.), also called lucerne, is the most important forage which
cultivated in the most parts of the world. The main source of alfalfa is Southwest Asia, especially Iran. Alfalfa is
a perennial forage legume which normally lives four to eight years, but can live more than 20 years, depending
on type of its variety and climate. In the most regions, alfalfa is generally harvested three to four times and can
be done up to 12 times per year. Many types of insects are found in alfalfa fields including beneficial, and
harmful insects, which feed on the leaves, flowers, root and seeds. Amongst them, thrips are a group of insects
belonging to the order Thysanoptera. Thrips have been considered in most areas. Different species of thrips have
been recorded on alfalfa fields in western Iran i.e. Odontothrips confosus Priesner, Odontothrips iranensis
Mirab-balou et Chen, Thrips tabaci, Frankliniella intonsa (Trybom), F. pallida (Uzel), Haplothrips reuteri
(Karny) and Neohydatothrips gracilicornis (Williams).Therefore, it is critical to determine the biodiversity status
of the thrips in order to manage its population.
Materials and Methods: To study the biodiversity of thrips species in different alfalfa cuttings, the sampling
was weekly carried out during April to the middle of September 2016 in alfalfa fields (1-year-old, 3-years-old
and 4-year-old) of Eyvan city (Ilam province), the west of Iran. The specimens were collected using shaking
alfalfa plants in a white tray and transferred them to vials containing 75% ethanol. After transferring to the
laboratory, all thrips specimens were mounted onto slides, and identified at the species level. The dominant
thrips species were determined and biodiversity of thrips species in different alfalfa cuttings was calculated by
biodiversity indices i.e. Shannon-Wiener, Simpson, Margalef and Evenness Shannon.
Results and Discussion: In the present study, 10 thrips species belonging to six genera and four different
families were collected and identified from alfalfa fields. Among the collected species, the highest and the lowest
frequency was obtained for Thrips tabaci (59.12%) and Tenothrips frici (0.24%), respectively. According to the
calculations, the Shannon-Wiener, Simpson, Margalef and Evenness Shannon indices in 1-year-old alfalfa field
were 2.71 ± 0.04, 0.92 ± 0.04, 3.49 ± 0.02 and 0.89 ± 0.01, in 3-year-old alfalfa field were 2.26 ± 0.09, 0.88 ±
0.009, 2.58 ± 0.18 and 0.91 ± 0.006, and in 4-year-old alfalfa field were 2.09 ± 0.14, 0.85 ± 0.01, 2.31 ± 0.29 and
0.92 ± 0.01, respectively. The results showed that the Shannon-Weiner, Simpson and Margalef indices of thrips
species in 1-year-old alfalfa field were significantly higher than the 3 and 4-year-old alfalfa, however, the
Evenness Shannon in 4-years-old alfalfa field was more than 1-year-old and 3-years-old alfalfa fields, this
difference was not significant.
Conclusion: In this study, Shannon-Wiener index values varied between at least 2.09 in a 4-year-old alfalfa
and a maximum of 2.71 in a 1-year-old alfalfa fields. The range of Shannon-Weiner index variables from 0 –5
and typically from 1.5 - 3.5. Lower values of this range indicates the presence of tension in the environment and
instability, and more than it showed an increasing the biodiversity of the area. These values are good in
comparison to the range of Shannon-Weiner index variables, which are generally between 1.5 and 3 in their
sources. As the age of the plant raises, the amount of food decreases, so, insects less likely tend to establish on
the host plants, and their variety will be reduced. Thrips tabaci is one of the most important pests with more than
300 host plants in the world. Considering that in the present study T. tabaci is a dominant species in the alfalfa
fields, its infestation level should be managed correctly with respect to control method.
