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20154
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Subject: Entomology × End date: 2015 × Start date: 2015 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Uptake and metabolism of imidacloprid in cotton (Gossypium hirsutum Linn.) and its persistence in soil
    (PAU, 2015) Sahoo, Sanjay Kumar; Singh, Balwinder
    The uptake and metabolism of imidacloprid in cotton was studied by following its application as seed treatment and foliar application. Samples of cotton were analyzed by High Performance Liquid hromatograph. Maximum residues of imidacloprid and its metabolites were found to be 1.52 and 5.23 mg kg-1 in cotton leaves collected 15 days after sowing the seed treated with imidacloprid @ 3.5 and 14 g a.i. kg-1. The initial deposits of total imidacloprid were found to be 2.05 and 6.19 mg kg-1 in leaves collected 0 day after its application @ 20 and 80 g a.i. ha-1, respectively. For the corresponding dosages, the residues of imidacloprid in cotton leaves were declined to below the determination limit of 0.01 mg kg-1 collected 45 and 60 days after sowing the treated seed and 21 and 45 days after foliar application. The samples of lint, cotton seed oil and seed cake did not reveal the presence of imidacloprid residues at harvest for both the cases. In soil samples, total residues of imidacloprid were found to be 1.59 and 3.39 mg kg-1 collected after 7 day of sowing the treated seed @ 3.5 and 14 g a.i. kg-1 respectively. These residues could not be detected 60 days after sowing for both dosages. Following foliar application of imidacloprid @ 20 and 80 g a.i. ha-1, the total residues of imidacloprid were found to be 0.48 and 1.42 mg kg-1 in soil samples collected on the same day. The residues dissipated to below the determination limit after 15 and 30 days of application. Based on enzyme activity studies, it has been found that imidacloprid at the recommended dosage did not show any deleterious effect on dehydrogenase, phosphatase and urease activities.
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    ThesisItemOpen Access
    Phenotypic and genetic variability in Helicoverpa/Heliothis spp. in Punjab
    (PAU, 2015) Kaur, Arshdeep; Arora, Ramesh
    The studies on phenotypic and genetic variability in Helicoverpa armigera populations collected from different crops, viz. American (non-Bt) cotton, pigeon pea, Egyptian clover (berseem), sunflower and tomato, and different locations, viz. Ludhiana, Abohar and Gurdaspur were conducted during 2012-2013. The morphometric studies showed that larvae, male and female pupae and male and female adults belonging to different locations and collected from different host plants differed significantly with regard to weight and length. The cotton population recorded the maximum larval weight (532.36± 4.45 mg) while minimum was recorded in the sunflower population (402.07± 4.46 mg). Among locations, maximum larval weight was recorded in the Gurdaspur population (505.37± 3.82 mg) followed by the Ludhiana population (456.32± 3.78 mg). Minimum larval weight was recorded in the Abohar population (380.09± 4.91 mg). The male genitalic studies showed identical shape indicating that all the populations represent the same species, i.e. H. armigera, however, the populations differed significantly with regard to male genitalic morphometry. Inter-host and inter-location breeding studies on different populations of H. armigera revealed that all crosses were fertile. Maximum fecundity and per cent egg hatch was recorded in the cotton♂×pigeon pea♀ cross (384.90 eggs per female and 79.86%, respectively) and minimum fecundity was recorded in the cotton♂×sunflower♀ (172.20 eggs per female) pairing. Among the crosses of H. armigera populations collected from different locations, maximum fecundity and per cent egg hatch was recorded in Ludhiana♂×Gurdapur♀ pairing (272.20 eggs per female and 80.12%, respectively) and minimum in case of the Gurdaspur♂×Abohar♀ cross (64.25 eggs per female and 65.88%, respectively). The molecular characterization of H. armigera populations revealed that two clusters were formed based on RAPD-PCR in both inter-host and inter-location experiments. The nucleotide sequences of all the seven mt COI region variants of H. armigera were submitted to Boldsystems and Bold IDs were granted accordingly. Based on sequence analysis of mitochondrial cytochrome oxidase I gene, the Ludhiana population differed from Gurdaspur population by the 0.5 per cent and from Abohar population by 0.2 per cent while the latter two differed from each other by 0.7 per cent. Among populations infesting various host plants, the cotton population differed from sunflower by 0.2 per cent, Egyptian clover by 0.3 per cent and tomato and pigeon pea by 0.4 per cent. The study thus found little genetic variation based on alignment of DNA sequences based on mitochondrial cytochrome oxidase I region, supporting the idea that H. armigera represented a single species with no specialized sub-species. The beet armyworm Spodoptera exigua was recorded as a new pest on Egyptian clover.
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    ThesisItemOpen Access
    Biochemical basis of insecticide resistance in Spodoptera litura (Fabricius) on cole crops
    (PAU, 2015) Kaur, Prabhjot; Kang, B.K.
    Studies were conducted to monitor the magnitude of insecticide resistance in tobacco caterpillar, Spodoptera litura against different insecticides viz., emamectin benzoate, chlorantraniliprole, indoxacarb, spinosad, quinalphos and deltamethrin collected from different vegetable growing areas of Punjab. Chlorantraniliprole with LC50 value of 0.029- 0.088 ppm and emamectin benzoate with 0.037-0.081 ppm were found to be most toxic insecticides against all the tested population of S. litura followed by indoxacarb, spinosad, quinalphos and deltamethrin. Resistance levels for quinalphos and deltamethrin ranged from 21.80 to 38.90 fold and 24.8 to 64.2 fold, respectively. Different synergists i.e. Triphenyl phosphate (TPP), Diethyl maleate (DEM) and Piperonyl butoxide (PBO) at ratios of 1:1, 1:2, 1:4 and 1:6 were tested with deltamethrin to know their synergistic effect and evaluated against three different populations of S. litura collected from Malerkotla resistant (MAL), Hoshiarpur susceptible (HSP) and deltamethrin resistant Malerkotla selected strain (MAL-Sel strain) by leaf dip method. The results obtained in the present study revealed that PBO at 1:4 had highest synergistic effect on the susceptible (HSP-3.91 fold) and MAL (8.24 fold) followed by TPP and DEM (1:4). However, the stronger synergism of TPP (1:4) was 23.67 fold followed by PBO (21.30 fold) and DEM (18.26) at 1:4 respectively, in case of MAL-Sel strain which suggests the involvement of esterases and monooxygenases in imparting resistance to various insecticides. Selection with deltamethrin increased the activities of esterases and monooxygenases by 3.58 and 3.91 times in S. litura proving their role in pyrethroid mediated resisitance. Inhibition studies with quinalphos showed (2.4 times) higher tolerance in Malerkotla selected (MAL-Sel) strain than susceptible one implying the role of insensitive AchE in insecticide resistance. Activity of these enzymes and insensitivity of AchE can be used as biochemical tools for monitoring insecticide resistance in S. litura.
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    ThesisItemRestricted
    Morphological and molecular characterization of regional crop pollinating bee fauna (Hymenoptera: Apoidea)
    (PAU, 2015) Makkar, Gurpreet Singh; Chhuneja, Pardeep Kumar
    Studies on ‘Morphological and molecular characterization of regional crop pollinating bee fauna (Hymenoptera: Apoidea)’ were conducted at Punjab Agricultural University, Ludhiana (India), during 2012-2014. Investigations were carried out on the relative abundance and diversity of the bee fauna on six bee floral crops (Brassica juncea, Brassica napus, Brassica rapa, Helianthus annuus, Trifolium alexandrinum and Cajanus cajan) in three agroclimatic zones of Punjab, morphological characterization of bee species based on 40 morphometric characters and molecular characterization of the bee fauna through DNA barcoding. In all, 17 bee species with complete DNA barcodes and morphometric characterization, comprising of 5 new species records: 1 in India, viz., Andrena agilissima, and 4 in Punjab, viz., Tetragonula iridipennis, Megachile anthracina, Megachile creusa and Megachile ramakrishnae, representing 7 genera, 5 subfamilies and 4 families of superfamily Apoidea were recorded. Apis mellifera was the most dominant (over the crops and zones except in C. cajan), with relative abundance ranging from 17.6 per cent on C. cajan to 26.5 per cent on T. alexandrinum. Megachile lanata and Megachile bicolor were the most abundant pollinators on C. cajan in all the three zones. The relative abundance of Apis species varied from 34.4 per cent on C. cajan to 77.8 per cent on T. alexandrinum. Thus, the relative abundance of non-Apis bees (social and solitary) revealed a substantial stake with minimum of 22.2 per cent on T. alexandrinum to the maximum of 65.6 per cent on C. cajan. The species richness was the highest (11) on B. juncea and B. napus, and the lowest (8) on T. alexandrinum. The species diversity, based on 12 diversity indices, was the highest in Sub-mountain Undulating zone followed by the Central Plain and Western zone. Temporal species diversity was higher at 1100 and 1400 h than at 0800 and 1700 h. The 40 morphological characteristics recorded for the 17 bee species revealed significant differences within and across the family groups, of which, thorax width, abdomen width, clypeus length, clypeus width, inter-orbital distance through antennal sockets, compound eye length, distance between antennal sockets, ocellocular distance, forewing length, jugovannal index, hind tibia length and hind basitarsus length revealed relatively higher discriminating ability among the species. DNA sequencing for the mitochondrial cytochrome c oxidase (cox1 or COI) gene was carried out for all the 17 bee species. The DNA barcodes were generated for all the 17 species and were submitted to BOLD (The Barcode of Life Data System). Phylogenetic relationships among the barcoded species were decoded with dendrogram based on mt COI gene sequences which grouped various operational taxonomic units (OTUs) based on evolutionary relationship among themselves. The present study is pioneering work in the country having succeeded in decoding the crop and region specific species diversity, species taxonomy and phylogenetics achieved through combined strengths of traditional taxonomy and DNA barcoding techniques. The information generated on the regional and crop specific species richness, abundance, diversity and DNA sequences of bee fauna would serve as baseline data, facilitating as a potential identification tool for further accounting of bee diversity, for ecological studies of bee communities, documenting shifts or declines in the species composition, and initiating their habitat management programmes.