PG Thesis
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/2
Browse
126 results
Search Results
Item Characterisation of insecticide degrading bacterial endosymbionts of cowpea pod bug Riptortus pedestris (Hemiptera :Alydidae)(Department of Agricultural Entomology, College of Agriculture,Vellanikkara, 2026) Lakshmipriya, E SCowpea Vigna unguiculata (L), commonly known as vegetable ‘meat', is widely grown in India for its high nutritional value, drought tolerance, and ability to improve soil fertility. Riptortus pedestris (Hemiptera: Alydidae), is a major pest of cowpea, causing significant damage during the post-flowering phase to immature pods and reducing pod quality and yield up to 80 per cent (Prasad et al., 2021). The cowpea pod bug has increasingly shown resistance to commonly used insecticides, largely due to endosymbiotic bacteria it acquires from soil during the second instar. Identifying and characterising endosymbiotic bacteria and assessing their insecticide-degrading potential can aid in developing environmentally sound strategies. Hence, this study, “Characterisation of insecticide-degrading bacterial endosymbionts of cowpea pod bug Riptortus pedestris (Hemiptera: Alydidae)”, conducted at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara (2023–2025), aimed to characterise the culturable endosymbionts of R. pedestris and evaluate their insecticide-degrading potential for targeted pest management. To identify and characterise the endosymbiotic bacteria of R.pedestris, adult pod bugs were collected and dissected under sterile conditions to separate the midgut. Serially diluted gut contents were plated on nutrient agar and Burkholderia cepacia selective agar. Four culturable endosymbiotic bacteria were identified from the M4 region of the pod bug, viz., Burkholderia cepacia, Pantoea dispersa, Macrococcus equipersicus, and Serratia sp. Morphological characterisation showed that B. cepacia produced light pink, smooth, raised, circular colonies with entire margins and Gram-negative rod-shaped cells. P. dispersa formed yellow, smooth, circular colonies with entire margins and slightly raised elevation, appearing as Gram-negative rods. M. equipersicus developed orange, smooth, circular colonies with an umbonate elevation and entire margins, exhibiting Gram -positive cocci. Serratia sp. produced white, smooth, raised, round colonies with entire margins and Gram - negative rod-shaped cells. Sequences were deposited in NCBI with accession numbers for B. cepacia (PX128431), P. dispersa (PX128399), and M. equipersicus (PX128423). Metagenomic profiling showed that the cowpea pod bug gut microbiome was dominated by few taxa, reflected in a low Shannon index (0.63) and Chao1 richness (37). Burkholderiaceae, particularly the Burkholderia–Caballeronia–Paraburkholderia cluster, comprised 94.8 per cent of all reads, while other groups such as Bacillaceae, Streptococcaceae, Caulobacteraceae and the genera Bacillus, Pantoea, and Azospirillum occurred only in trace amounts. The insecticide-degrading potential of the culturable endosymbiotic bacteria was assessed using the spectrophotometric method and validated through enumerating bacterial growth and Gas chromatography-flame photometric detector (GC-FPD) analysis. Each bacterial cultures was amended with each insecticide, and B. cepacia showed the highest degradation ability, especially for quinalphos 25% EC followed by malathion 50% EC. OD₆₀₀ for Burkholderia cepacia recorded 1.84 for quinalphos 25% EC and 1.76 for malathion 50%EC, far higher than M. equipersicus (0.38), Serratia sp. (0.21), and P. dispersa (0.38). The corresponding bacterial count reached 1.95 × 10⁷ CFU/mL in quinalphos 25%EC and 1.81 × 10⁷ CFU/mL in malathion 50% EC, compared to the control (1.13 × 10⁷ CFU/mL). GC-FPD analysis further confirmed the degradation potential of B. cepatia, wherein the quantity of quinalphos 25% EC dropped from 10 ppm (0 day) to 3.79 ppm (3rd day) and 0.97 ppm (7th day), whereas the corresponding reduction in control was 9.04 ppm and 5.27 ppm, respectively, at the third and seventh day. Malathion 50% EC declined from an initial quantity of 2 ppm to 0.49 ppm (3 rd day) and became undetectable by day seven, whereas in the control, the reduction was 1.45 ppm (3rd day) and 0.008 ppm (7th day). Agar well diffusion assay was conducted to identify the most effective antimicrobial agents against B. cepacia. Among the treatments, chloramphenicol (25 ppm) showed a clear inhibitory effect against Burkholderia, with a distinct inhibition zone of 7.625 mm, followed by lemongrass essential oil (1.375 mm). Sequential application of chloramphenicol (25 ppm) followed by malathion 50% EC (2mL/L) resulted in 97.5 per cent mortality, while their combined application resulted in 92.5 per cent mortality on the third day. Additionally, egg laying was inhibited in both treatments. However, malathion alone caused 65 per cent mortality only. Beauveria bassiana (1×10⁸ cells/mL), neem oil nanoemulsion (500 ppm), and lemongrass essential oil (1000 ppm) exhibited marginal lethality. Burkholderia symbiosis markedly enhanced the biological fitness of R. pedestris. To study the fitness offered by Burkholderia, two groups, i.e. symbiont-colonised (Sym) and non-colonised (Apo) pod bugs, were reared. The morphometric analysis revealed that symbiotic adults were larger, with a mean body length of 15.20 ± 0.061 mm (males) and 16.6 ± 0.042 mm (females) while for apo symbiotic, it is 12.3 ± 0.064 mm (males) and 13.4 ± 0.054 mm (females). Adult longevity was higher in sym. insects (33.05 ± 0.76 days) as against 22.2 ± 0.57 days in apo symbiotic. The fecundity was higher to the tu ne of 65.28 ± 1.93 eggs in symbiotic, whereas it was 34.57 ± 1.45 in apo symbiotic females. In conclusion, this study established the symbiosis of B. cepacia with R. pedestris, which significantly enhanced the biological fitness and insecticide degradation in the host. Symbiont-targeted pest management offers an eco-friendly approach against R. pedestris. Most effective antimicrobials against B. cepacia need to be identified for the sustainable management of R.pedestris in cowpea.Item Pests of medicinal plants in Kerala(Department of Agricultural Entomology, College of Agriculture , Vellanikkara, 2026) Hisana Jabeen, Vdicinal plants are known to Indian traditional healers since time immemorial. Kerala is known for its rich biodiversity of medicinal plants that support both traditional and modern healthcare practices. When cultivated in large areas, medicinal plants are much more prone to pest attacks, which cause considerable damage. Since limited information was available on pests of medicinal plants, the present study entitled "Pests of medicinal plants in Kerala" was conducted to document the pests associated with medicinal plants in the region, to generate DNA barcodes of cryptic species collected and to study the biology and population dynamics of indigo psyllid, Euphaleropsis isitis, an important pest of Indigofera tinctoria. Purposive sampling surveys were carried out in 32 locations across 10 districts of Kerala, covering 15 agroecological units distributed among five agroecological zones. The study documented 55 pest species associated with 10 selected medicinal plants viz., I. tinctoria, Ocimum spp., Coleus aromaticus, Plectranthus vettiveroides, Withania somnifera, Plumbago spp., Piper longum, Kaempferia galanga, Pseudarthria viscida and Desmodium gangeticum. Additionally, 17 species were recorded from 13 medicinal plants viz., Pogostemon cablin, Aristolochia indica, Tylophora indica, Asparagus racemosus, Thespesia populnea, Strobilanthes cusia, Saraca asoca, Tephrosia purpurea, Ruta graveolens, Aegle marmelos, Calotropis gigantea, Hibiscus sp. and Helicteres isora. Of the total pests collected, 31 were under the order Hemiptera, 24 Lepidoptera, 10 Coleoptera, two Orthoptera, one mite species and snail. This study revealed 40 new host associations and a new distributional record for Sphenoptera konbirensis (Coleoptera: Buprestidae). Barcoding of seven insect pests viz., Orphanostigma abruptalis, Bemisia tabaci, Aleurothrixus trachoides, Lygaeus sp., Cochlochila bullita, Icerya aegyptiaca and Plumbago leaf miner was done. For this, genomic DNA was isolated, mitochondrial cytochrome oxidase I (mtCO1) was amplified and sequenced. The in-silico analysis revealed that O. abruptalis, Lygaeus sp., B. tabaci, and A. trachoides showed more than 98 per cent similarity, whereas C. bullita, I. aegyptiaca and Plumbago leaf miner showed less than 93 per cent similarity with the available sequences in the NCBI database. The sequences were submitted to NCBI to obtain accession numbers and to BOLD for generating species specific barcodes. The indigo psyllid, E. isitis is a major pest infesting I. tinctoria. There were no comprehensive studies on the biology and factors affecting the population build-up of E. isitis on indigo plant. This study represented the first detailed investigation on the biology and population dynamics of the indigo psyllid. The biology was studied in the laboratory at ambient conditions to document its morphology and developmental duration. Eggs were elongate oval, pale yellow and later turned black, with an incubation period of 6 ± 0.77 days. The dorsoventrally flattened nymphs passed through five instars, completing development in 15.5 ± 1.75 days. The total life cycle lasted for approximately 21.5 days. Adults were small, with slender antennae, forewings marked with black spots and variable abdominal colouration. Females (2.62 ± 0.127 mm long, 0.92 ± 0.050 mm wide) were larger than males (2.24 ± 0.077 mm long, 0.88 ± 0.062 mm wide). Mean longevity was 17.4 ± 3.55 days in females and 16.4 ± 3.83 days in males. Females laid an average of 209.9 ± 61.83 eggs over a period of 13.1 ± 3.20 days with a brief pre-oviposition period of 2.2 ± 0.4 days. The population of different life stages of E. isitis, viz., egg, nymph and adult of psyllid, were recorded from September 2024 to August 2025 and correlated with the weekly average of one-week prior weather data. The population was comparatively higher during July-August. The abundant population of nymphs and adults during the rainy season could be attributed to the lush growth of the plant stimulated by rainfall. Egg did not show correlation with any weather factors. Nymph had positive significant correlation with rainfall. The adult exhibited a significant negative correlation with maximum temperature and bright sunshine hours. A significant positive correlation was observed between evening humidity and adult population, while rainfall displayed a highly significant positive correlation. A further study extending over 2-3 years is required to assess population dynamics and their correlation with weather factors.Item Effect of insect mediated pollination in culinary melon, Cucumis melo var. acidulus Naudin(Department of Agricultural Entomology, College of Agriculture ,Vellayani, 2025) Vismaya, S A; Amritha, V SThe present study entitled “Effect of insect mediated pollination in culinary melon Cucumis melo var. acidulus Naudin” was conducted at Department of Agricultural Entomology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala during 2022 to 2024. The objectives of the study were to assess the foraging behaviour of insect visitors, major pollinator-flower interaction and effect of pollination in culinary melon. The popular culinary melon variety, KAU Vishal was used in this study, and the crop was raised both under open field conditions and augmented (bee hive installed) condition. Observations on floral structures viz., flower spread, stamen characters, pistil characters etc., were taken after 10 percentage bloom. Insects visiting culinary melon were documented and the foraging behavior of major pollinator was assessed at weekly intervals for two months. The developmental changes in culinary melon (flower, fruit and seed development) due to bee visits were assessed by installing an Indian bee hive with six frame bee strength among the treatments; augmented, open- pollinated, hand pollinated and in pollinator excluded conditions. Studies on the floral biology of culinary melon revealed that flower bud initiation and anthesis was earlier in male flowers (31.30 days and 32.10 days) when compared to female flowers (38.70 and 49.80 days). Variation in the time of anthesis was also observed among the male (7:45 am) and female flowers (8:04 am). The count as well as the viability of pollen grains on anther and number of pollen grains deposited on the stigma was highest during 1100 -1300 h, which coincided almost with that of the stigma receptivity. A total of 19 insect visitors belonging to 18 genera, 8 families, and 4 orders were recorded, of which 15 species were identified as pollinators in terms of their foraging behaviour. Among them, six were nectar foragers and nine were both nectar and pollen foragers. Based on Shannon-Wiener diversity index, peak pollinator diversity was recorded during 0900-1100 h. Of these pollinators, Apis cerana indica Fab., Nomia 70 strigata Fab. and Ceratina binghami Cockerell recorded highest relative abundance (7.68, 3.70 and 3.04 bees mֿ ² 5 min ⁻¹) and number of loose pollen grains (60,000, 22,000 and 12,500). Thus, A. c. indica was ranked as the efficient pollinator of culinary melon in terms of the pollination efficiency index. Foraging behaviour of A. c. indica exhibited significant temporal variation throughout the day. Peak visitation rates were recorded during 1100-1300 h (11.83 ± 0.68 flowers min⁻¹) when compared to early morning (0700-0900 h: 7.79 ± 0.31 flowers min⁻¹) and late evening (1700-1900 h: 6.16 ± 0.68 flowers min ⁻¹). The number of bees visiting a single bloom was highest during 1100-1300 h (1.92 ± 0.05 bees 5 min⁻¹), followed by 0900 -1100 h (1.76 ± 0.13 bees5 min ⁻¹) and 1300-1500 h (1.62 ± 0.08 bees 5 min ⁻¹). The average time spent by bees on anthers as well as on the stigma was significantly high in the morning hours (0900-1100 h: 11.34 ± 0.84 sec and 0900-1100 h: 65.05 ± 29.65 sec), while, the number of returning foragers was highest during 1300- 1500 h (10.83 ± 0.83 bees 5 min ⁻¹). These findings highlight mid-morning to early afternoon as the optimal period for pollination activity in culinary melon. The impact of bee visits on flower, fruit and seed development under augmented (1-12 visits), open-pollinated, hand pollinated and in pollinator excluded conditions was assessed. Studies on the quantification of endogenous hormone levels such as Auxin (IAA) and Gibberellin (GA₃) revealed that open-pollinated flowers exhibited the highest auxin concentration (19.50 ± 0.20 ppb) which was followed by flowers with seven bee visits (6.32 ± 1.53 ppb). GA₃ was not detected in any treatment, indicating either its negligible role at anthesis in pollination response or due to the concentrations below detection limits. The quantitative and qualitative yield parameters of culinary melon as part of the fruit and seed development among the treatments were also observed. The fruit set percentage (0 to 100%) in culinary melon varied with the number of bee visits, with 100 per cent fruit set both in nine bee visits and open pollinated ones. Though percentage fruit set increased with bee visitation, the percentage of malformed fruits were also found increasing in flowers with 10 visits and beyond. Maximum fruit weight (2.43 ± 0.11 kg), fruit length (46.00 ± 1.00 cm), fruit diameter (11.46 ± 0.41 cm), flesh thickness (3.90 ± 0.10 cm), and TSS content (3.03 ± 0.06 °Brix) were recorded from 71 seven bee visit treatment. The seed quality parameters viz., seed set (1265.67 ± 140.10 seeds per fruit), total seed weight (11.02 ± 0.07 g), 100-seed weight (2.37 ± 0.06 g), and seed germination percentage (97.33 ± 0.57 per cent) were also maximum in the seven bee visits treatment. The present study revealed that A. c. indica was the dominant pollinator in terms of the Pollination efficiency index with peak foraging activity during 0900 to 1300 h. The count as well as viability of pollen grains on anther and number of pollen grains deposited on the stigma coincided almost with that of the stigma receptivity. The syngenesious type of anthers in culinary melon flowers with more than half of them inside the corolla cup and the similarity in length of Indian bee proboscis and stamen, signifies the relevance of bee pollination. Developmental changes in flower, fruit and seed among the pollination treatments indicated that both open-pollinated flowers and those receiving seven bee visits exhibited elevated auxin (IAA) levels, while the treatment, seven bee visits exhibited superior fruit and seed traits. These results highlight the critical role of A. c. indica in pollination, yield and quality of fruits in culinary melon.Item Taxonomy of thrips fauna (Thysanoptera: Terebrantia: Thripidae) on ornamental plants in Kerala(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2024-02-28) Amal Poulose; Haseena BhaskarThis belonging to the order Thysanoptera are considered as one of the most economically important group of insect pests worldwide. Some species of thrips act as vectors by transmitting plant viruses. The order comprises about 6288 species of thrips under two suborders viz., Tubulifera and Terebrantia. The suborder Terebrantia primarily consists of phytophagous species in eight families of which the family Thripidae is the largest. The members of Thripidae are widely reported as serious pests of ornamental plants. However, no systematic study has been conducted so far to document the fauna of Thripidae on ornamental plants in Kerala. The present study entitled “Taxonomy of thrips fauna (Thysanoptera: Terebrantia: Thripidae) on ornamental plants in Kerala” was carried out during the period, 2022-23. The research aimed at studying the taxonomy of thrips species of the family Thripidae infesting ornamental plants of Kerala, preparing an illustrated key for the identification of species of Thripidae and generating DNA barcode for cryptic species of thrips collected during the study. Purposive surveys were undertaken in different localities of Kerala covering 43 geographical locations across 14 districts. Thrips specimens were collected from different ornamental plants including flowering trees and the GPS coordinates of the feographical locations as well as the host plants were recorded. The specimens were assigned unique accession numbers and preserved in AGA mix, and then mounted onto permanent slides as per the standard procedure. The slide mounted specimens were used for morphological characterization, and the illustrations of key taxonomic characters and morphometry were made. The amino acid sequences of mitochondrial cytochrome oxidase subunit I (mtCO-I) were analysed for 13 accessions representing eight species. The study recorded 20 species under 14 genera in three subfamilies (Panchaetothripinae, Sericothripinae and Thripinae) from Kerala. The subfamily Thripinae was the most dominant group with 12 species under six genera. The genus Thrips was more diverse with seven species viz., Thrips andrewsi, T. Flavus, T. florum, T. hawaiiensis, T. orientalis, T. paravispinus and T. simplex. The other species in the subfamily includes Chaetanaphothrips signipennis, Echinothrips americanus, Frankliniella schultzei, Microcephalothrips abdominalis and Scirtothrips dorsali. The subfamily Panchaetothripinae recorded seven species under seven genera viz., Astrothrips tumiceps, Caliothrips indicus, Copidothrips octarticulatus, Heliothrips haemorrhoidalis, Retithrips syriacus, Rhipiphorothrips cruentatus and Selenothrips rubrocinctus. The subfamily Sercicothripinae was represented by a single species, Neohydatothrips samayunkur. An illustrated dichotomous taxonomic key for the identification of subfamilies, genera, and species of thrips collected during the study were prepared. A species distribution map was prepared for the Thripidae infesting ornamental plants of Kerala, using Quantum GIS software. A total of 50 plants under 45 genera in 27 families were recorded as hosts for 20 species of thrips species collected in this study. The predominant families of host plants were Asteracea, Oleaceae, Apocynaceae and Rubiaceae. Thrips parvispinus recorded widest host range of 16 host plants in 11 families followed by Microcephalothrips abdominalis (12 host plants in 3 families), Thrips orientalis (9 host plants in 4 families) and Thrips hawaiiensis (8 host plants in 7 families) from Kerala. The DNA barcodes wre generated for eight species viz., Thrips simplex, T. andrewsi, T. parvispinus, T. hawaiiensis, Astrothrips tumiceps, Selenothrips rubrocinctus, Heliothrips haemorrhoidalis and Neohydatothrips samayunkur. A phylogenetic tree was constructed with 27 sequences of different thrips species (13 sequences in the study plus 14 sequences retrieved from NCBI database) and the sequence of aphid, Aphis gossypii as an outgroup in MEGA 11, using UPGMA method. The sequences were submitted to GenBank (NCBI) and BOLD to generate species-specific barcodes. The study identified Echinothrips americanus as a new distribution record for India. The study also identified six new distribution records of thrips for Kerala viz., Neohydatothrips samayunkur, Chaetanaphothrips signipennis, Microcephalothrips abdominalis, Thrips andrewsi, T. Flavus, and T. simplex. The invasive thrips species, T. parvispinus recorded 11 new host plants viz., Cosmos sulphureus, Tabernaemontana sp., Asystasia gangetica, Hibscus rosa sinensis, Canna indica, Rhododendron spp., Spiraea cantoniensis, Antirrhinum majus, Zephyranthes rosea, Uncaria tomentosa and Justicia carnea, suggesting that the species can pose significant threat to ornamental plants of Kerala. The study indicates the need to explore the potential of the above species to become invasive and establish in new habitats. The biotic and abiotic factors that regulate thrips populations on ornamental plants also have to be investigated. Further, thrips fauna associated with other crops of Kerala need to be explored.Item Pests of ornamental plants in commercial horticultural nurseries of Kerala(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2024-03-12) Ardra, S; Deepthy, K BIn Kerala, commercial horticultural nurseries serve as the cradle of ornamental plant trade. The incidence of pests is one of the major challenges faced by ornamental plants in nurseries. However, literature pertaining to pests of ornamental plants in horticultural nurseries of Kerala is scanty. Hence, the present study entitled "Pests of ornamental plants in commercial horticultural nurseries of Kerala", was carried out to document the insects and non-insect pests associated with different ornamental plants. Purposive sampling surveys were carried out in 50 nurseries from 11 districts of Kerala. Insect and non-insect pests infesting 43 flowering ornamentals and 17 ornamental foliage plants were collected. The pests were preserved as per standard protocols and got identified by experts in the relevant taxa. Among the documented pests, sucking pests predominated (69%) followed by defoliators (15%), non-insect pests (11%), flower feeders (4%) and stem borers (1%). The study recorded 50 species of sucking insect pests in two orders viz., Hemiptera and Thysanoptera. Hemipteran pests include 28 species of scale insects (Pseudococcidae- mealybugs (6), Coccidae- soft scales (11), Diaspididae- armoured scales (7), Monophlebidae-giant scales (3), Ortheziidae- ensign scales (1)), eight species of aphids (Aphididae), four species of whiteflies (Aleyrodidae) and one species of lacewing bug (Tingidae). Thysanopteran pests include and nine species of thrips in two families viz., Thripidae (7) and Phlaeothripidae (2). The defoliator pests include five species of caterpillars (Noctuidae (2), Nymphalidae (1), Pyralidae (1), and Sphingidae (1)), three species of leaf-feeding beetles (Curculionidae (2) and Chrysomelidae (1)) and three species of grasshoppers (Acrididae). Three species of flower feeders which includes one species of bud-boring caterpillar (Noctuidae) and two species of flower beetles (Scarabaeidae (1) and Chrysomelidae (1)) as well as one species of stem borer (Cerambycidae) were documented. The non-insect pests documented include six species of mites (Tetranychidae (5) and Eriophyidae (1)) and two species of snails (one Ariophantidae and one unidentified species of aquatic snail) Among the mealybugs documented, Ferrisia virgata recorded a wider host range of seven ornamental plants species, while the highest infestation was recorded by Phenacoccus solenopsis on hibiscus. The scale insect Ceroplastes rubens was recorded on four plant species, while the per cent pest infestation was found to be higher for Coccus viridis on ixora plants. Among aphids, the highest pest infestation was noticed in Aphis gossypii infesting Ixora, while among whiteflies, Bemisia tabaci recorded the highest infestation on Euphorbia pulcherrima. Of the thrips recorded, Thrips florum infesting rose showed the highest infestation percentage in nurseries. Spodoptera litura had been the polyphagous defoliator surveyed and found to infest nine species of ornamental plants. Among the defoliators, higher infestation was recorded by Polytela gloriosa on Hymenocallis littoralis, Myllocerus subfasciatus on Melastoma sp. and Nisotra basselae on hibiscus. The primary polyphagous flower feeder causing severe economic damage to the ornamental plants recorded during this study was Popillia japonica. The stem borer, Cleonaria bicolor, whose grubs hollowed out the tender stems while adults scraped the midribs, veins and stem, had been documented from Ixora coccinea. The mite species Tetranychus gloveri exhibited a wide host range of five ornamental plants. The snail Macrochlamys indica was found to feed on many species of ornamental plants, but the infestation was severe on Canna indica. Even though the nursery owners were reluctant to reveal the pest management strategies, the common cultural practices adopted by them were: cleaning and proper monitoring at timely intervals, greenhouse protective structures to reduce the incidence of pests, intermittent mist irrigation to manage the excess temperature rise under polyhouse conditions, innovative irrigation practices like Ebb and flow system that helped in maintaining the plant's health and soil-less potting media like fibre enriched giffy that reduced the incidence of soil pests. Mechanical measures involved hand-picking in the case of caterpillars and pruning of the old or pest-affected branches to reduce the spread of pests like thrips or whiteflies. Yellow and blue sticky traps were used to manage the population of sucking pests in nurseries. Biological measures involved the use of Neem oil garlic emulsion (2%), Nimbecidine (Azadirachtin 0.03%), entomopathogens like Lecanicillium lecani (Vertilac) against aphids and whiteflies and Beuveria bassiana against lepidopteran pests. The common pesticides used in nurseries include Thiamethoxam (Actara), Fipronil 5% SC (Agadi), Dimethoate 30%EC, Chlorantraniliprole 18.5%SC (Coragen), Bifenthrin 10% EC(Boxer)and Quinalphos 25% EC(Ekalux). Molecular characterization of nine sucking insect pests was performed by isolation of genomic DNA and amplification of mitochondrial cytochrome oxidase one (mtCO1) locus using specific primers. The sequencing of PCR products and in silico analysis of three species of aphids, two species of each of thrips, mealybugs, and scales, were carried out. All the sequences showed a similarity between 95-100 percent with the sequence in the NCBI database and hence agreed with the morphological identification. The sequences were submitted to the NCBI database and uploaded to Barcode of Life Data Systems (BOLD), and specific barcodes were generated. The study documented 73 species of pests infesting 60 species of ornamental plants and the existing pest management practices in horticultural nurseries. Further studies on biology, seasonal incidence, and geographical distribution of major pests of ornamental plants have to be carried out to evolve specific, and environment-friendly pest management strategies for horticultural nurseries in the state.Item Ecological engineering for pest management in rice Oryza Sativa L(Department of Agricultural Entomology, College of Agriculture , Vellanikkara, 2024-03-15) Meera Krishnan; Sreeja, PEcological engineering (EE) for pest management is a strategy to enhance the abundance, diversity, and effectiveness of natural enemies in an agricultural ecosystem. Although EE has gained acceptance as a pest management tactic, there still exist knowledge gaps in the identification of the best floral resources for the population build up and biocontrol potential of natural enemies. Hence, the present study entitled Ecological engineering for pest management in rice Oryza sativa L was carried out during 2022-23 to identify suitable flowering plants for habitat management in rice and evaluate their efficacy for ecological pest management. The olfactory response of predators viz.,lady bird beetle (Micraspis discolor), ground beetle (Ophionea nigrofasciata), green mirid bug (Cyrtorhinus lividipennis) and parasitoids Trichogramma chilonis and T. japonicum to different the flowers was assessed in a six arm olfactometer. In each arm of the olfactometer, ten flowers each of sesame, cowpea and cosmos were individually inserted and for marigold and okra, only one flower was used. The arm without flower served as the control. Ten adults of each predator and twenty adults of each parasitoid were released at the center of the olfactometer. The number of predators and parasitoids settled per arm at 5, 10, 15 and 20 min. after release (MAR) as well as the distance covered per min. was assessed. Micraspis discolor showed the highest attraction towards flowers of cowpea and okra (2.33 each arm-1) at 20 MAR followed by marigold (1.00 arm-1) and sesame and cosmos (0.67 each arm-1). The distance covered towards cowpea was 10.61 cm min-1. and whereas for okra it was 7.37 cm min-1. Similarly, for O. nigrofasciata, the highest response was recorded towards cowpea (2.00 arm-1) followed by marigold (1.67 arm-1) and sesame (1.00 arm-1). The distance covered was also higher in cowpea (3.50 cm min 1 ). Cyrtorhinus lividipennis recorded the highest attraction towards sesame (2.67 arm-1) followed by cowpea (1.33 arm-1) and marigold (1.00 arm-1), which showed significant difference with the control. The distance covered was also high in sesame (4.82 cm min 1 ) followed by cowpea (3.42 cm min-1). As for parasitoids, highest attraction of T. chilonis was found towards cowpea (4.33 arm-1), while that of T. japonicum was towards sesame (2.67 arm-1). Thus, the behavioural response studies of predators and parasitoids revealed a significantly higher preference towards the flowers of cowpea, sesame and marigold. To identify the attractive compounds in the volatiles of flowers, through GCMS analysis, their extraction was conducted through head space method and solvent extraction. The headspace analysis of marigold flowers identified seven major compounds, with insect attractant properties. The compounds were alpha ocimene, myrcene, limonene, cis ocimene, trans ocimene and beta caryophyllene. The attractant compounds of marigold flowers through solvent extraction were caryophyllene, heneicosane, squalene, eicosane, tetrapentacontane, tetracontane, hexatriacontane, heptadecane, octadecane 1-chloro- and dotriacontane and that of cowpea flowers were eicosane, heneicosane, hexadecane, dotriacontane, tetracosane, heptadecane, octadecane 1-chloro- and diisoctyl phthalate. Similarily, the attractant compounds from sesame flowers were eicosane, octacosane, nonacosane, beta-bisabolene, heptadecane, dotriacontane, tetracontane, octadecane 1-chloro- and hexatriacontane. A field experiment was laid out to study the effect of flowering plants in ecological pest management in rice with four treatments: T1- PoP of KAU, T2- PoP in combination with flowering plants, T3- farmers practice and T4- untreated control. The seedlings of best three flowers selected from the olfactometer studies viz., marigold, cowpea and sesame were planted around the rice bunds on the day of transplanting to evaluate their effect on natural enemies and insect pests in rice. The population of major insect pests and natural enemies was recorded at 15,30,45,60,75 and 90 days after transplanting. The extent of damage of stem borers (Scirpophaga incertulus and S. fusciflua) was significantly lower in ecological engineering plot (T2) (2.52 %) followed by the PoP (2.86 %), farmers practice (3.26 %) compared to untreated control (5.39 %). Similarly, the mean damage of leaf folder (Cnaphalocrosis medinalis) was lowest in T2 (1.24 %) which was on par with T1 (1.28 %). The mean population of leafhoppers (Nephotettix nigropictus, N. virescens and Cofana spectra) was lowest in PoP (0.37 m 2 ), while for hispa, Dicladispa armigera, the population in all the treatments was non significant. The population of rice bugs (Leptocorisa spp.) was lowest in PoP (4.43 m 2 ) followed by farmers practice (4.86 m-2), and PoP with flowering plants (7.06 m-2) at 90 DAT. Ecological engineering plot recorded a significantly higher population of all natural enemies as against the control, PoP and farmers practice. Five species of coccinellids were recorded from the ecological engineering plot, viz., M. discolor, Coccinella transversalis, Harmonia octomaculata, Cheilomenes sexmaculatus, and Brumoides suturalis, The highest population of ground beetles (O. nigrofasciata) was recorded in ecological engineering plot (1.60 m-2) followed by control (0.90 m-2). Similarly, significantly higher population of rove beetles and damselflies (2.94 and 1.41 m-2 respectively) were recorded in EE plot. Seven species of spiders viz., Tetragnatha javana, T. mandibulata, Pardosa pseudoannulata, Neoscona theisi, N. elliptica, Argiope catenulate and Oxyopes javanus were documented wherein the population was highest in ecological engineering plot (1.97 m-2). The hymenopteran parasitoids were recorded through sweep netting and significantly higher population was recorded in ecological engineering plot (2.20 /5 sweeps), followed by control (1.06 /5 sweeps). The major parasitoids recorded under Ichneumonidae were Xanthopimpla sp., Trathala flavoorbitalis, Amyosoma sp., Isotima sp., Metopius rufus, Goryphus sp. and Stenobracon nicevelli, whereas Tropobracon sp., and Cardiochiles sp. were documented under Braconidae.The parasitization on stem borer egg mass by Tetrastichus sp. and Telenomus sp. was observed, in which the extent of total parasitism was 92.5 per cent in ecological engineering plot, followed by 72.5 percent in the control. The yield recorded in PoP and ecological engineering plot was 529.73 g m-2 and 513.80 g m-2 respectively and was on par with each other, while the control plot recorded the lowest yield of 263.46 g m-2. The benefit-cost ratio in the ecological engineering plot is 2.16 while the control recorded a ratio of 0.95. The present study identified three flowering plants viz., cowpea, marigold and sesame having the potential to enhance the population of predators and parasitoids in the rice ecosystem. Hence the study will pave the way to develop a habitat management module for pest management in rice. Further studies to identify additional plant species for habitat management are to be carried out. Detailed investigations on the impacts of floral resources on the growth and development of entomophagous insects have to be undertaken to fortify conservation biological control strategiesItem Bio -ecology and management of rice caseworm, Paraponyx stagnalis (Zeller) (Lepidoptera : Crambidae)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025-02-13) Muhammed Arshad, V; Karthikeyan, KThe rice caseworm, Parapoynx stagnalis (Zeller) (Lepidoptera: Crambidae), has emerged as a serious pest of rice, particularly in South India in recent years. It is reported to cause a reduction in yield by about 30 per cent in rice. Sporadic incidence of the caseworm has been reported recently from many rice growing tracts of Kerala as well. Yet, hardly any study has been conducted either on the biology or management of this pest. The study was conducted at the Department of Agricultural Entomology, Regional Agricultural Research Station, Pattambi during 2023-24. The objectives of the study were to investigate the biology of rice caseworm, the population dynamics of rice caseworm and its natural enemies and to evaluate the bio-efficacy of plant products and insecticides against the pest. The life cycle of P. stagnalis consisted of egg, larva, pre-pupa, pupa, and adult. The caseworm recorded an incubation period of 3.25 days in male and 3.48 days in female. The total larval period was 16.93 and 18.63 days in male and female, respectively. The pre-pupal and pupal duration was 1.30 and 5.4 days in male and 1.58 and 6.18 days in female, respectively. The total duration from egg to adult was shorter for male (30.83 days) as compared to female (34.52 days). The maximum adult emergence was recorded during 6.00 pm to 12.00 am. Pre-oviposition, oviposition and post-oviposition periods of female moth lasted for 1.3, 2.4, and 1.7 days, respectively. The sex ratio was found to be 1:1.43. The female moth laid 45 to 104 eggs, varying in different seasons with 43 to 81 per cent hatchability. The morphometrics study on different stages of caseworm showed that the mean length and width of the egg were 0.65 ± 0.12 and 0.50 ± 0.05 mm. The length and width of 1st, 2nd, 3rd, 4th, and 5th larval instars were 1.95 ± 0.23 and 0.21 ± 0.0 mm, 5.21 ± 0.18 and 0.39 ± 0.09 mm, 6.92 ± 0.13 and 0.65 ± 0.06 mm, 8.95 ± 0.21 and 0.88 ± 0.14 mm, 11.45 ± 0.20 and 1.28 ± 0.14 mm. The pupa measured 7.95 ± 0.34 mm in length and 1.54 ± 0.13 mm in width. In the Rabi season, the highest moth population was recorded in the field after four weeks of transplanting in sweep net catch, viz., 8.5 moths/10 sweeps during 3rd week of January, while in Kharif, the highest catch (7.5 moths/10 sweeps) was recorded during 1st week of September. In light trap, the highest catch was obtained during 3rd week of August in Kharif (7.86) and 2nd week of November (12.14) in Rabi season. The correlation study concluded a significant positive correlation with maximum temperature (0.756) and a significant negative correlation with minimum temperature (-0.88) and relative humidity (-0.778) in the Kharif season. In contrast, no significant correlation was obtained in the Rabi season. The joint effect of weather variables showed a significant negative correlation with minimum temperature and relative humidity (Tmin*RH) in the Kharif season. The highest leaf damage was caused by 4th instar larva with a mean per cent damage of 26.74. The rice field weed, Isachne miliaceae (Naringa) was identified as an alternate host to rice caseworm. In the field, the spider, Plexippus paykulli (Araneae: Salticidae) was recorded as a predator of rice caseworm larvae. A hymenopteran wasp, Apsilops scotinus (Ichneumonidae) was recorded as a larval pupal parasitoid of rice caseworm. The evaluation of oil cakes and bio-pesticides under net house conditions against rice caseworm larva showed that mahua cake at 3 % was the most effective treatment followed by B.t and mahua cake at 2 %. Mahua cake at 3% recorded the lowest leaf damage (7.73 %) followed by mahua cake at 2%, neem cake at 3 %, and B.t. In the field evaluation, Cartap hydrochloride + Emamectin benzoate was found to be the superior treatment recording 100 per cent mortality in Rabi and 95.95 per cent mortality in Kharif. This was followed by Carbosulfan and Fipronil. During Rabi season, significant mortality was observed in the treatment with Bacillus thuringiensis (71.99 %). A higher yield was recorded in the plot treated with Cartap hydrochloride Emamectin benzoate (3344.13 kg/ha in Rabi and 3117.30 kg/ha in Kharif), followed by fipronil and carbosulfan. This study provides valuable insights into the biology, ecology, population dynamics, and management of Parapoynx stagnalis, contributing to the development of effective and sustainable management strategies for rice caseworm, for the enhancement of rice production and food security.Item Radiofrequency heating for the management of rice weevil Sitophilus oryzae (L.)(Coleoptera:Curculionidae) and lesser grain borer Rhyzopertha dominica (Fabricius)(Coleoptera:Bostrichidae)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025-03-04) Prashanth PatilIndia is the leading country in the export of rice. The infestation of storage pests, notably the rice weevil, Sitophilus oryzae and lesser grain borer, Rhyzopertha dominica causes a significant loss in the quantity and quality of stored grains. Phosphine use effectively manages stored pests, but insect resistance, residue concerns, strict import regulations, and rising demand for organic products highlight the need for chemical-free alternatives like radiofrequency (RF) heating to protect high-value commodities.. Hence, this study was carried out to assess the effectiveness of RF heating for the management of rice weevil, S. oryzae and lesser grain borer, R. dominica, and to study the impact of RF disinfestation on the quality parameters of rice grains. Eggs, grubs (15 ± 2 day old), pupae, and adults (one week old) of S. oryzae and R. dominica were exposed to RF dryer (40.68 MHz, 10 kW) at three different levels of electrode height (190, 195, and 200 mm) and conveyor speed (6, 8, and 10 m/h) and compared with an untreated control. The order of susceptibility among different life stages of lesser grain borer at 195 mm electrode height and 8 m/h conveyor speed was adult>grub>egg>pupa. S. oryzae was highly susceptible to RF heating, leading to complete mortality of all the stages except pupa at all the treatment combinations. The susceptibility of grubs, eggs, and pupae of R. dominica were comparable, whereas adults were highly vulnerable to RF heating. The mortality of immature stages was assessed based on the per cent decrease in adult emergence over control. Lowering the electrode height of RF dryer increased the mortality of all life stages of S. oryzae and R. dominica. Highest mortality of eggs, larvae, pupae, and adults was obtained at the lowest electrode height of 190 mm. Similarly, the mortality of eggs, larvae, pupae, and adults of S. oryzae and R. dominica increased significantly by decreasing the conveyor speed. The lowest conveyor speed of 6m/h significantly reduced adult emergence and recorded the highest mortality of all the developmental stages of S. oryzae and R. dominica. The analysis of the interaction effect of electrode height and conveyor speed of RF dryer demonstrated that the mortality of different developmental stages of S. oryzae and R. dominica increased with a decrease in electrode height and conveyor speed. There was no adult emergence when the eggs, grubs and pupae of S. oryzae were exposed to RF heating. Meanwhile, the adult emergence of R. dominica was completely inhibited only at the lowest conveyor speed of 6 m/h at all three electrode heights. RF heating resulted in the complete mortality of adults of rice weevil at all the treatment combinations. Lesser grain borer adults were more tolerant to RF heating, with complete mortality observed at all the electrode heights at a conveyor speed of 6 m/h and at the electrode heights of 190 and 195 mm at a conveyor speed of 8 m/h. All other treatment combinations did not cause complete mortality of R. dominica adults. Per cent weight loss was significantly reduced over control when R. dominica and S. oryzae eggs were exposed to RF heating. Meanwhile, weight loss was significantly reduced over control only when S. oryzae grubs were subjected to RF heating. The impact of RF heating on the quality parameters of rice grains was analysed after exposure to RF heating. Moisture, amylose, and cooking time of rice grains decreased with the decrease in electrode height of RF dryer. The moisture content at all the treatment combinations was significantly lower over control. Amylose content and cooking time did not vary significantly over control by RF heating at various combinations of electrode height and conveyor speed. Similarly RF heating did not adversely affect the colour of rice as there was no significant colour change over control after RF heating. Three combinations of electrode height and conveyor speed (190 -6 mm m/h, 195-6 mm-m/h,200- 6mm-m/h) resulted in the complete mortality of all life stages of S. oryzae and R. dominica. Also, there was no significant difference in amylose, cooking time, and colour values of rice grains at these treatment combinations over control. The lowest temperature recorded after RF treatment was 56.9°C in the 200 mm-6 m/h treatment combination. This indicates that a temperature of 56.9°C generated through RF heating can effectively control all life stages of S. oryzae and R. dominica by retaining the quality parameters of the rice grains. Hence, radiofrequency heating at an electrode height of 200 mm and a conveyor speed of 6 m/h can be commercially employed in the complete disinfestation of all the stages of S. oryzae and R. dominica without compromising the quality of rice grains.Item Mechanisms of host plant resistance in Tomato (Solanum lycopersicum L.) genotypes to cotton whitefly (Bemisia tabaci Genn.)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025) Naveena Unnikrishnan.Tomato (Solanum lycopersicum) is one of the most widely cultivated crops worldwide, with India ranked second in global production (Ministry of Agriculture and Farmers Welfare, MOAFW, 2023). The cotton whitefly (Bemisia tabaci) is a major pest of tomato, inflicting direct damage by feeding on phloem sap and serving as a vector for the tomato leaf curl virus (ToLCV). The extensive use of synthetic insecticides has led to resistance in whitefly populations, alongside concerns about environmental and health risks. As a result, developing host plant resistance has emerged as a sustainable alternative for pest management. Building on a previous study at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, which evaluated fifty tomato genotypes for whitefly resistance under polyhouse conditions (Tejaswee, 2023), the current study, titled "Mechanisms of host plant resistance in tomato genotypes to cotton whitefly," was conducted during 2023-2024. The primary objectives were to evaluate the resistance of different tomato genotypes to cotton whitefly under field conditions and to investigate the mechanisms behind host plant resistance. Twenty tomato genotypes selected from the previous research (Tejaswee, 2023) were evaluated for their resistance to whitefly under field conditions. The genotypes exhibited significant variation in the density of all life stages of Bemisia tabaci. The number of whitefly eggs ranged from 1.33 ± 0.30 (LC Palakkad) to 11.80 ± 0.22 (EC 617060) on the top leaves, 0.90 ± 0.40 (LC Palakkad) to 11.03 ± 0.29 (EC 617060) on the middle leaves, and 0.73 ± 0.24 (LC Palakkad) to 7.63 ± 0.39 (EC 617060) on the bottom leaves. Nymph populations varied from 1.27 ± 0.21(LC Palakkad) to 11.23 ± 0.37 (EC 617060) on the top leaves, 0.93 ± 0.16 (LC Palakkad) to 8.73 ± 0.37 (EC 617060) on the middle leaves, and 0.70 ± 0.21 (LC Palakkad) to 6.47 ± 0.24 (EC 635520) on the bottom leaves. Adult whitefly populations ranged from 0.73 ± 0.30 (LC Palakkad) to 12.50 ± 0.37 (EC 617060) on the top leaves, 0.50 ± 0.35 (LC Palakkad) to 10.33 ± 0.55 (EC 638522) on the middle leaves, and 0.43 ± 0.15 (LC Palakkad) to 8.03 ± 0.27 (EC 617060) on the bottom leaves. The pooled mean counts for all life stages were highest on the top leaves, followed by the middle and bottom leaves. Three genotypes viz., LC Idukki, LC Palakkad, and EC 519806 had mean whitefly populations under 2.62 per leaf, classifying them as resistant. Six genotypes with a mean population between 2.62 and 5.31 were moderately resistant, while six others were moderately susceptible (5.31–8), and five genotypes with >8 were highly susceptible. Additionally, the screening of genotypes for the incidence of Tomato leaf curl virus (ToLCV) and the coefficient of infection (CI) revealed that LC Palakkad, LC Idukki, and EC 519806 were highly resistant to the leaf curl disease. In the free-choice assays, whitefly settling and oviposition preferences were monitored at regular intervals in the customised experimental arenas. EC 617060 had the highest whitefly count, with 9.33 ± 0.577 per leaf at 24 hours and 7 per leaf at 48 hours. No whiteflies were observed on LC Palakkad and LC Idukki after 48 hours. LC Palakkad and LC Idukki had the lowest oviposition preference, with only 0.67 eggs/cm², while the highest oviposition (7.33 eggs/cm²) was recorded on EC 635520 and EC 638522. The epicuticular wax content of the tomato genotypes varied from 0.032 ± 0.002 mg/cm² (EC 617060) to 0.197 ± 0.002 mg/cm² (LC Palakkad). A significant negative correlation was observed between wax content and both oviposition and settling preferences of B. tabaci. Additionally, settling and oviposition preferences were negatively correlated with glandular trichome density, but positively correlated with non-glandular trichome density and trichome length. In the no-choice experiment, the developmental parameters of B. tabaci were observed in clip-cages. Oviposition rates (OR) on the tomato genotypes ranged from 0.31 ± 0.10 to 4.24 ± 0.58 eggs per day. Pre-adult survival (PS) rates varied from 0.57 ± 0.07 to 0.90 ± 0.01, while adult survival (AS) rates ranged from 0.72 to 0.98 ± 0.02. The developmental period (DP) of B. tabaci ranged from 21.95 ± 0.03 to 31.97 ± 2.77 days. Oviposition, pre-adult survival, and adult survival showed negative correlations with phenol, flavonoid, and alkaloid content, but positive correlations with free amino acid content and relative water content. In contrast, the developmental period was positively correlated with phenol, flavonoid, and alkaloid content, and negatively correlated with free amino acid and relative water content. The present study identified LC Idukki, LC Palakkad, and EC 519806 as highly resistant to whitefly, B. tabaci, exhibiting low level of whitefly population and ToLCV incidence, reduced settling preference, oviposition, survival rates, and longer developmental periods. While glandular trichomes and epicuticular wax contribute to resistance through antixenosis, the study highlights the crucial role of antibiosis, especially through phenolic compounds, in disrupting the development of B. tabaci. These results emphasize antibiosis as the primary resistance mechanism against B. tabaci in the evaluated tomato genotypes. Thus, the present study offers valuable insights for further research into host plant resistance mechanisms, aiding the development of sustainable and economically viable integrated pest management strategies for tomato cultivation.Item Baseline susceptibility of rice brown planthopper, Nilaparvata lugens stal(Hemiptera : Delphacidate) to selected insecticides(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025-02-06) Akshay Krishna; Smitha, M SThe development of insecticide resistance in insect pests is one of the major problems in the field of pest management. Data on baseline susceptibility to insecticides must be generated to track the evolution of resistance among different pest populations. This knowledge is vital for developing successful insecticide resistance management (IRM) strategies that aim to delay the resistance evolution and prolong the useful life of an insecticide. A comprehensive understanding of the biochemical mechanisms contributing to the shift in susceptibility is essential for ensuring the long-term sustainability of insecticide applications. In light of this, the present investigation entitled “Baseline susceptibility of rice brown planthopper, Nilaparvata lugens Stal (Hemiptera: Delphacidae) to selected insecticides” was carried out during 2022-2024 at the Department of Agricultural Entomology, with the objective of monitoring baseline susceptibility of Nilaparvata lugens to selected insecticides and studying the biochemical mechanism responsible for the change in susceptibility to insecticides. The BPH populations were collected from three major rice-growing tracts of Kerala, viz., Kuttanad in Alappuzha district, Alagappanagar in Thrissur district, and Pattambi in Palakkad district. A population maintained in the glasshouse since 2006 was procured from the Indian Institute of Rice Research (IIRR), Hyderabad. Another population, which was maintained without any pesticide exposure since 2005 at the Rice Entomology Section, Zonal Agricultural Research Station (ZARS), Mandya, was also procured to keep as a susceptible population. The collected populations were assigned respective codes, viz., KTD, TCR, PTB, HYD, and MND, and maintained separately on the rice variety, TN1, without any pesticide exposure, in a polyhouse at 29°C temperature and humidity of 75 per cent. Information on BPH outbreaks, insecticides used, and usage patterns was gathered from farmers in the sampling locations through personal inquiry. An intensive application of various insecticides, mainly imidacloprid and thiamethoxam, in doses higher than the recommended ones, was practiced in all the sampling fields. Newer molecules such as pymetrozine and triflumezopyrim were also used in the Kuttanad area. In the rice-growing regions of the Thrissur district, farmers switched to dinotefuran and reported it to be effective. In certain rice-growing regions of Pattambi, pymetrozine was also used. The laboratory bioassays were performed against imidacloprid 17.8 SL (Tatamida), thiamethoxam 25 WG (Actara), clothianidin 50 WG (Dantotsu), dinotefuran 20 SG (Token), afidopyropen 50 DC (Sefina), flonicamid 50 WG (Ulala), and pymetrozine 50 WG (Chess) to determine the median lethal concentrations (LC50). The resistance ratio (RR) was assessed by comparing the LC50 values with that of the laboratory susceptible population. All the populations of N. lugens displayed a significant shift in LC50 with respect to MND population, and were resistant to imidacloprid and thiamethoxam based on the test for the hypothesis of equality. The LC50 value for imidacloprid ranged from 150.79 ppm in KTD to 41.89 ppm in HYD, compared to 4.04 ppm in MND. The KTD population had the highest RR of 37.25-fold, followed by the TCR (31.92-fold) and PTB (24.77-fold) populations. With respect to thiamethoxam, the LC50 value ranged between 119.90 ppm in KTD (30.19-fold RR) and 79.87 ppm in HYD (20.11-fold RR), in contrast to 3.97 ppm in MND. A significant shift in susceptibility to clothianidin was recorded with KTD, TCR, and PTB populations with respective RRs of 3.35-, 2.20- and 1.36-fold. In the assay with dinotefuran, the hypothesis of equality was rejected for only KTD and TCR populations with respective LC50 values of 7.14 ppm and 6.11 ppm, as against 2.62 ppm in MND. The LC50 value for afidopyropen ranged from 1.50 ppm in KTD to 0.97 ppm in HYD, compared to 0.44 ppm in MND. According to the test for the hypothesis of equality, only KTD population showed a significant shift of 3.63-fold. However, all the populations were susceptible to flonicamid according to the test for the hypothesis of equality. A significant shift in susceptibility to pymetrozine was recorded with LC50 values ranging between 234.28 ppm in KTD and 81.70 ppm in HYD as against 40.48 ppm in MND population. The activity of detoxifying enzymes was quantified and compared with that of the susceptible population to examine the role of detoxifying enzymes in the shift in susceptibility to insecticides. The PTB, HYD, KTD, and TCR populations have shown 2.55-, 1.91-, 1.84-, and 1.62-fold increases in carboxylesterase (CarE) activity, respectively. Significantly higher titers of cytochrome P450 (Cyt P450) activity were displayed by KTD and TCR population, with 5.43-fold and 4.04-fold increase respectively. The Cyt P450 activity of PTB (1.70-fold) and HYD (1.55-fold) populations were on par. The relative activity of glutathione S-transferase (GST) was the highest in PTB (5.19-fold), followed by 5.00-fold in HYD, 3.49-fold in TCR, and the least in KTD (2.85) population. The research study revealed a shift in susceptibility and the development of resistance to some selected insecticides among the populations of N. lugens, and the result was confirmed with the test for the hypothesis of equality. The possible role of detoxifying enzymes in the shift in susceptibility was also established.