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ThesisItem Restricted Biology, population dynamics, crop losses and management of emerging pest, Spodoptera exigua (Hübner) in chickpea(Punjab Agricultural University, 2023) Sidhu, Kawartej Singh; Ravinder SinghField and laboratory studies were conducted to determine the biology, population dynamics, crop losses and management of Spodoptera exigua in chickpea during Rabi 2021-22 and 2022-23 at PAU, Ludhiana. Eggs of S. exigua were laid in masses covered with scales. The larval and pupal period lasted for 16.79 and 9.37 days on chickpea, whereas on mungbean it was 14.69 and 8.46 days, respectively. The best developmental and reproduction values were recorded on mungbean as compared to chickpea. In population dynamics, early, normal, and late sown chickpea, mean number of larvae ranged from 0.00 to 15.10, 0.00 to 13.20, and 0.40 to 11.60, respectively. As the sowing dates delayed, number of egg masses, larval number and foliar damage by S. exigua decreased. In estimation of crop losses, there was no foliar damage where the crop was protected by nylon mesh cages. Protected treatment had significantly lowest mean foliar and pod damage than unprotected treatment. In insect density method, lowest mean seed yield was recorded in treatment with highest larval infestation of seven larvae per meter row (1079 kg ha-1) as compared to control (1623 kg ha-1). In cultural and mechanical control of S. exigua, highest mean yield (1628kg ha-1) was recorded in treatment consisting of hand collection and destruction of egg masses and young larvae of S. exigua followed by where 2 rows of linseed were sown as intercrop after 10 rows of chickpea (1527 kg ha-1). Among different biopesticides/biorationals tested against S. exigua in chickpea, chlorantraniliprole 18.5 SC @ 125 ml ha-1 was found most effective over all other treatments. S. exigua is emerging as a serious pest of chickpea under Punjab conditions which can be managed by using cultural, mechanical and chemical methods.ThesisItem Restricted Induced host plant resistance in pigeonpea against spotted pod borer, Maruca vitrata (Fabricius)(Punjab Agricultural University, 2022) Khokhra, Shivani; Taggar, Gaurav KumarThe studies on “Induced host plant resistance in pigeonpea against spotted pod borer, Maruca vitrata (Fabricius)” were conducted during Kharif 2020 and 2021. Field screening of pigeonpea genotypes revealed that the genotype AL 1747 consistently performed better towards M. vitrata infestation during both years (Kharif 2020 and 2021). The exogenous application of Jasmonic acid (JA) (100 µM) and Salicylic acid (SA) (5.0 mM) on pigeonpea plants triggered the induction of biochemical parameters (enzymes and secondary metabolites) after 12 and 24 h of application, respectively. Pre-treatment with JA (100 µM) followed by infestation with M. vitrata after 12 h elicited a strong defense response in both the resistant (AL 1747) and susceptible (MN 1) genotypes. AL 1747 responded better to the exogenous application of elicitors and M. vitrata than the susceptible genotype MN 1. The induced effect was highest one day after the treatment (in both JA and SA) and showed a declining trend thereafter with no changes in the activities of defensive enzymes and secondary metabolites after 7 days of treatment. Both JA and SA induced an antioxidative response in pigeonpea plants against M. vitrata, which, in turn, affected the insect development, nutritional indices as well as the metabolism of M. vitrata. Imbalance in the digestive enzymes significantly reduced the nutritional indices (AD, ECI, ECD and RGR) of M. vitrata in JA-treated plants. Insect, as a counter-response to plant defense, increased the activities of glutathione-S-transferases (GST) and glucose oxidase (GOX). However, a significant negative correlation was observed between the detoxifying enzyme (GST) and larval weight (r= -0.790**). The GOX activity and larval weight exhibited a non-significant negative correlation with each other post-elicitor application. SA also led to an alteration in the activities of digestive and defense related enzymes in M. vitrata; however, the effect was not as pronounced as JA. An alteration in insect defensive and digestive enzymes and upregulation of plant secondary metabolites by exogenous application of elicitors (either in the pre-/or simultaneous application) indicates that modulation of pigeonpea defense can increase the effectiveness of the host plant to defend against M. vitrata herbivory.ThesisItem Restricted Influence of abiotic factors on development and behaviour of rice leaf folder, Cnaphalocrocis medinalis (Guenee)(Punjab Agricultural University, 2023) Simranpreet Kaur; Suri, K SThe present studies on “Influence of abiotic factors on development and behaviour of rice leaf folder, Cnaphalocrocis medinalis (Guenee)” were conducted at Punjab Agricultural University, Ludhiana during 2019-22. The impact of variable minimum:maximum temperature for 10:14 h, CO2 and RH on C. medinalis revealed that larval duration, pupal duration, adult emergence, male longevity, female longevity, incubation period and hatchability decreased, whereas female proportion and fecundity of C. medinalis increased with increase in temperature (22:32°C to 26:35°C), CO2 (400 to 450 ppm) and RH (75 to 85%). The shortest larval duration of 7.5 days, pupal duration of 6.0 days, male longevity of 4.5 days, female longevity of 7.75 days, incubation period of 2.25 days, hatchability of 47.19 per cent and least adults emergence (5.25 adults) was recorded at elevated temperature (26:35°C), CO2 (450 ppm) and RH (85%), whereas the maximum fecundity (142.25 eggs) and female proportion (0.99) was recorded at the same elevated conditions. Food consumption, CI, AD and RGR increased, whereas ECI, ECD and RCR of C. medinalis larvae decreased with increase in temperature, CO2 and RH. Maximum food consumption (0.0450 g larva-1), CI (0.0965), AD (84.43%) and RGR (0.0770 mg mg-1day-1) was recorded at elevated temperature (26:35°C), CO2 (450 ppm) and RH (85%). Leaf folding pattern, employing double and multiple leaves for feeding and pupation was witnessed at elevated temperature, CO2 and RH. Activity of enzymes viz. AChE, Esterase, GST, Proteases and SOD in C. medinalis larvae increased as 4.96 μg of free thiol formed/min/mg protein, 9.86 μg of β-napthol formed/min/mg protein, 1.81 mmole of CDNB-GSH conjugate formation/min/mg protein, 3.49 mmol of tyrosine released/min/mg protein and 3.80 units/min/mg protein, respectively, whereas activity of Catalase decreased (7.48 µmoles of H2O2 decomposed/min/mg protein) with increase in temperature from 22:32°C to 26:35°C, CO2 from 400 to 450 ppm and RH from 75 to 85 per cent. Total sugars, reducing sugars, phenols and flavonols in rice plants showed a positive linear regression equation while proteins and amino acids followed a negative linear regression equation, whereas chlorophyll showed a non-linear regression equation with temperature, CO2 and RH. The results of present study would facilitate the adoption of appropriate adaptation measures for C. medinalis management with respect to climate change.ThesisItem Embargo Syrphid diversity and feeding and ovipositional response of aphidophagous species(Punjab Agricultural University, Ludhiana, 2022) Paramveer Singh; Rabinder KaurThe present study entitled “Syrphid diversity and feeding and ovipositional response of aphidophagous species” was carried out at the Entomological Research Farm, G.S. Kalkat Laboratories, Punjab Agricultural University, Ludhiana. For the study of syrphid diversity, three different locations of Punjab viz. Ludhiana, Muktsar and Gurdaspur were visited at fortnightly interval for collection of syrphids. Total of fourteen syrphid species viz. Ischiodon scutellaris (Fabracius), Helophilus hybridus (Loew), Eristalinus anesus (Scopoli), Eristalis tenax (Linnaeus), Eristalinus arvorum (Fabricius), Stomorhina discolor (Feracius), Episyrphus balteatus (Dee Geer), Eupeodes corollae (Fabricius), Metasyrphus confrater (Weidemann), Eupeodes frequens (Matsmura), Melanostoma scalare (Fabricius), Sphaerophoria chongjini (Bonkowska) and Chrysotoxum baphyrum (Walker) belonging to two subfamilies (Syrphinae and Eristalinae) were reported. Among all these syrphid species E. balteatus was found to be most abundant in all the three locations. For the molecular identification, the mtCO1 gene was amplified using universal primers (HCO and LCO) and sequence of this gene from all fourteen syrphid species were subjected to blast analysis in NCBI data base for confirmation of syrphid species. On the basis of number of syrphid species and number individuals of each species Shannon Wiener diversity index was calculated. It was recorded that Gurdaspur population was found to show maximum diversity index (H=2.23 and 2.25) for both years i.e. 2020 and 2021. The laboratory experiments on functional response and numerical response of four predatory syrphid species viz. I. scutellaris, E. balteatus, E. frequens and M. confrater predating upon varying prey densities of Lipaphis erysimi and Brevicoryne brassicae revealed type II functional and numerical response. By all the four syrphid species an increase in the number of aphids consumed by single syrphid larva (first and second instar) and number of eggs laid by single female was found to be increased with respect to increasing initial prey density and after reaching to its upper asymptote it became stable or decreased monotonically. Under the experiment on effect of conspecific and other predators of oviposition response of four predatory syrphids species viz. I. scutellaris, E. balteatus, E. frequens and M. confrater in semi-field conditions, it was recorded that in the presence of coccinellid grubs, the number of eggs laid by one female of each syrphid species decreased remarkably and no egg laying found when there was no prey (aphid) was present on plant cut section.ThesisItem Open Access Characterization of CAPA peptide and its receptor in Bemisia tabaci (Gennadius)(Punjab Agricultural University, Ludhiana, 2022) Sudeshna; Jindal, VikasBemisia tabaci (Gennadius) is a species complex having economic importance with worldwide distribution. Being an exclusive phloem feeder, diuresis is a key physiological process that helps in excreting out the waste substances. CAPA peptide and its G-protein coupled receptor (GPCR) interaction is key factor responsible for diuresis process in insects. The present investigations aimed to functionally characterize CAPA receptor (CAPAr) gene, its expression profile and characterize the CAPA peptides activating the CAPAr in B. tabaci AsiaII 1. We identified two isoforms of CAPAr gene and named these as BtabCAPAr-1 (1263 bp, 421aa) and BtabCAPAr-2 (1065 bp, 355aa) that showed 98.26% and 98.56% identity with the predicted CAPAr gene sequence available in NCBI GenBank, respectively. The isoform differs by missing of 198 nucleotides and 66 aa residues in the BtabCAPAr-2 as compared to BtabCAPAr-1. The nucleotide sequence alignment of BtabCAPAr-1 and BtabCAPAr-2 isoforms with the reference gene (XM_019044129.1) revealed the nucleotide substitutions at 22 and 16 positions, respectively. Amino acid sequence alignment revealed that ‘Alanine’ in the predicted gene (XM_019044129.1) was replaced by ‘Glutamine’ in BtabCAPAr isoforms. BtabCAPAr-1 and BtabCAPAr-2 isoforms code for six and five exons, respectively, however, in BtabCAPAr-2 isoform, exon 3 was found missing. The BtabCAPAr-1 and BtabCAPAr-2 have seven and five transmembrane domain polypeptide, respectively. Phylogenetic analysis showed that BtabCAPAr gene isoforms and the CAPA receptor gene in the other insect orders forms formed a single clade, which depicts close association among them. The expression of BtabCAPAr gene was significantly high in the adult stage (3.76 fold) in comparison to the egg. The expression in egg, nymphal stages and pupal stage was statistically at par. RNAi of CAPAr gene in B. tabaci Asia II 1 resulted into reduced survival and fecundity of whitefly. Significantly high adult mortality was recorded when whiteflies were fed with dsBtabCAPAr @1.0 µg/µl (30.04%) in comparison to dsgfp @1.0 µg/µl (7.29%) after 96 hr of dsRNA feeding. After 48 hr of dsRNA feeding, mortality was significantly higher in dsBtabCAPAr @1.0 µg/µl (30.74%) in comparison to dsgfp @1 µg/µl (1.14%). The minimum fecundity was recorded in dsBtabCAPAr @1.0 µg/µl (53.51 eggs/ female) which was statistically on a par with dsBtabCAPAr @0.5 µg/µl (59.30 eggs/ female) and dsBtabCAPAr @0.1 µg/µl (61.76 eggs/ female) but significantly lower than dsgfp @1 µg/µl (85.79 eggs/ female) and sucrose (92.98 eggs/ female). The effect of dsBtabCAPAr feeding on the development duration of egg, nymphs, pupa and total development period and egg and nymphal mortality was found to be non-significant. The q-RT-PCR studies further confirmed the downregulation of CAPAr gene expression by 44.00 and 41.00 per cent in whitefly adults fed with dsBtabCAPAr @1.0 µg/µl and dsBtabCAPAr @0.5 µg/µl, respectively. The dsRNA in the artificial diet was found to be stable in concentrations viz. dsBtabCAPAr @1.0 µg/µl, dsBtabCAPAr @0.5 µg/µl and dsgfp 1.0 µg/µl upto 96 hr of feeding. Feeding and internalization of artificial diet was confirmed by observing blue stained whitefly adults fed with synthetic food dye (1%). The pharmacological characterization of BtabCAPAr-1 isoform was carried out through heterologous expression assay in Chinese Hamster Ovary cells. The BtabCAPAr-1 isoform responded strongly to CAPA-2 (EC50 = 0.053 nM) followed by CAPA-1 peptide (EC50 = 0.067 nM). However, BtabCAPAr-1 did not respond strongly to CAPA-3 peptide (EC50 = 1147 nM). The study showed high mortality and low fecundity when BtabCAPAr gene was silenced and CAPA-2 and CAPA-1 were identified as authentic peptides, which activate BtabCAPAr gene. These results proved that CAPAr gene may be potential target for development of novel pesticides through RNAi and peptidomimetics approach for effective management of whitefly.
