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Subject: Agricultural Entomology × Author: Altaf, Nilofar × Start date: 2000 ×
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    ThesisItemOpen Access
    Diversity of mites in promising flower crops and their management in Gerbera, Gerbera jamesonii Bolus
    (2021) Altaf, Nilofar; Rahman, S.
    Mites are among the most diverse arachnid group in terrestrial ecosystem. Therefore, a survey was carried out during the year 2018-2020 on “Diversity of mites in promising flower crops and their management in gerbera, Gerbera jamesonii Bolus in five different districts under Upper, Central and Lower Brahmaputra Valley Zones of Assam to know the diversity of phytophagous mites attacking flower crops. A random survey was carried out at different locations covering five different districts of Assam. The infested leaves were brought to the Acarology Laboratory, Dept of Entomology, AAU, Jorhat for the identification of different mite species collected from different flower crops like rose, gerbera, hibiscus, anthurium, orchid and marigold. A total of five different mite species belonging to the family Tetranychidae viz., Tetranychus pacificus McGregor, T. truncatus Ehara, T. okinawanus Ehara, T. bunda Flechtmann and T. piercei McGregor and five species under the family Tenuipalpidae viz., Brevipalpus californicus Banks, B. chilensis Baker, B. yothersi Baker, B. lewisi McGregor and B. obovatus Donnadieu were recorded. However, B. yothersi, T. bunda, T. pacificus and T. piercei are supposed to be new record from our country. Out of five districts, maximum number of 5463 individuals was collected from Kamrup district. The species diversity index (1.582) and richness indices (0.587) of mite species was found to be highest in Experimental Farm, Dept of Horticulture, Assam Agricultural University of Jorhat district, whereas the lowest species diversity index (0.342) and richness indices (0.133) were observed in Changamari Habigaon of Dibrugarh district. In case of Pielou’s eveness index for phytophagous mites, highest value of 0.892 was recorded from Potia gaon of Jorhat district and lowest value of 0.494 was recorded from Changamari Habigaon of Dibrugarh district. The major mite species collected from different locations during survey were brought to the Acarology laboratory, Dept of Entomology, AAU, Jorhat for morphometric study. The body measurements were taken under labovision phase contrast microscope. The study revealed that the male of T. pacificus possessed highest body length of 371.207±0.001μm compared to the females with body length of 289.625±0.003μm whereas lowest body length of 338.354±0.001μm was observed in the male of T. okinawanus. The morphometric study of the major false spider mite species revealed that the B. obovatus showed the highest body length of 287.392±0.001μm whereas the lowest body length of 269.257±0.400μm was observed in B. yothersi. The principal component analysis was done under SPSS 20.0 Statistical package which showed that in case of adult false spider mite species among 25 morphometric characters used for analysis of variance two parameters, viz., length of body and width of body significantly contributed towards variation among them. The Principal Component Analysis of two different morphometric characters indicates two Eigen values which were greater than one that explained 81.977 per cent variation amongst the false spider mite species. In case of adult male and female of spider mite species among 22 morphometric parameters used for analysis of variance, four parameters viz., body length, body width, length of gnathosoma and length of leg I significantly contributed towards variation among them. The principal component analysis of four different morphometric characters indicates four Eigen values which were greater than one that explained 93.590 per cent variation amongst the male and female spider mite species. As regards the management strategies, efficacy of different treatments, viz., Polygonum hydropiper L (aqueous and ethanol extract), biopesticides like Beauveria bassiana Vuill (Green Beauveria), Metarhizium anisopliae Sorokin (Green Meta), pestoneem, predatory mite, (Neoseiulus longispinosus),chemical like spiromesifen 240 SC as check were evaluated against T. truncatus in gerbera under Polycarbonate house, AINP on Agril. Acarology, AAU, Jorhat. Randomly selected leaves from each plot were brought to the laboratory and studied under Stemi 2000C microscope. The number of mites was recorded one day before and at 1, 3, 5 and 7 days after application of treatments. Out of these treatments, pestoneem (0.3%) was found to be most effective against mite population which resulted in 94.90 per cent reduction in 7 days after spraying in the year 2019 and 95.77 per cent reduction in the year 2020.