Browsing by Author "Sreeja, P"

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Bio- priming for enhancing seed quality, longevity and growth in rice (Oryza sativa L.)
(Department of Seed Science and Technology, College of Agriculture,Vellanikkara, 2026) Monika, K G; Dijee Bastian; Sreeja, P
The study “Bio-priming for enhancing seed quality, longevity and growth in rice (Oryza sativa L.)”, was carried out at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara, in two varieties, Uma and Manuratna with five treatments - Pseudomonas fluorescens (T₁), coconut water (T₂), P. fluorescens + Trichoderma viride + coconut water (T₃), hydropriming (T₄), and control (T₅). Seeds were dried to <10 per cent moisture and stored in gunny bags and polyethylene bags (700 gauge) for periodical evaluation of seed quality. Manuratna variety in gunny bags exhibited progressive deterioration, than poly bags storage, although the extent varied across treatments.After nine months, treatment T₃ (P. fluorescens + T. viride + coconut water) recorded the highest germination (83.50%), vigour index-II (1383), seedling dry weight (0.163 g), dehydrogenase activity (0.706 OD value), and protease activity by the end of gunny bag storage, and recorded longer shoot and root length, α-Amylase activity (2.29 mg maltose/min) under poly bag storage. T₁ (P. fluorescens) reported the highest values in seedling dry weight (0.167 g), least mean germination time by the end (9 months) of gunny bag storage and highest germination (83.50%), longer shoot and root length, increased dehydrogenase activity (0.778 OD) and protease activity were evident under poly bag storage. Uma stored in gunny bags, showed greater susceptibility to deterioration relative to Manuratna. At the ninth month, T₁ reported highest germination (82.50%), vigour index-II (1315), dehydrogenase activity, and protease activity (2.17 OD value) lowest mean germination time (4.36 days) under gunny bag, Whereas higher germination (82.50%) and dehydrogenase activity (0.747 OD value) reported in poly bag storage. Treatment T₃ (P. fluorescens + T. viride + coconut water) registered highest germination (81.00%), protease activity (2.28 OD value) and dehydrogenase activity at the end (9 months) of gunny bag storage, and in poly bag storage T₃ recorded highest germination (83.50%), vigour index II (1342). These results confirm that Uma deteriorates faster than Manuratna but benefits significantly from microbial priming. Insect infestation reported to increase toward the end (9 months) of storage. In Manuratna T₁ (P. fluorescens) recorded the highest undamaged seed weight (96.57 and 97.80 g), least damaged seeds (1.68 and 1.63 g), infestation per cent (5.57 % and 2.82 %) and adult insects (61.00 and 41.00) at the end of gunny and poly bag storage, respectively. Treatment T₃ (P. fluorescens + T. viride + coconut water) reported least adult insect count (18.00) under poly bag storage. Similar trends were observed in Uma, where T₁ consistently reported highest undamaged seeds (97.82 g), least damaged seeds (1.56 g), infestation per cent (6.55 %) in gunny bag storage, Treatment T₃ (P. fluorescens + T. viride + coconut water) registered highest undamaged seeds (99.10 g), lowest damaged seeds (1.05 g), number of adult insects (39.00) under poly bag storage. Seed infection report of Manuratna, at the end (9 months) of gunny and poly bag storage recorded least infection per cent in treatment T₁ (P. fluorescens) (24.00 % and 23.00 %, respectively) under blotter test method. T₃ (P. fluorescens + T. viride + coconut water) registered least infection (47.00 %) in agar plate test under poly bag storage. In Uma, T₁ (P. fluorescens) treatment recorded least infection in agar plate method (43.00% and 60.00%) at the end of gunny and poly bag storage, respectively. Whereas T₁ recorded lowest seed infection in blotter method (27.00%) under gunny bag storage. T2 (Coconut water priming) recorded least infection (24.00 %) in blotter method under poly bag storage. Growth studies in Manuratna, T₃ reported for accelerated flowering (78.75 days), superior root traits, total root length (3104.00 cm), surface area (524.00 cm²), and root volume (2.04 cm³). Plant height was highest in T₂ – coconut water (66.75 cm). In Uma, T₃ recorded highest field emergence (85%), grains per panicle (48.00) and maximum total root length (2840.75 cm), root surface area (523.00 cm²), and root volume (1.93 cm³). Plant height was greatest in T₁ (69.00 cm) and T₄ – hydropriming reported for earliest flowering (82.00 days). Seed treatment with P. fluorescens (10g/kg) recorded best for enhancing seed quality and storability followed by P. fluorescens (10g/kg) + T. viride (4g/kg) + coconut water (85%) treatment. Among different packaging, polyethylene bags retained higher seed quality and vigour over extended storage period. In pot culture studies of primed seeds T₃ consistently recorded superior for growth performance in both cultivars.
Bioactive metabolites of beauveria bassiana (Balsamo) vuillemin and its efficacy on tobacco caterpillars spodoptera litura (FAB.)
(Department of agricultural entomology, college of agriculture,Vellanikkara, 2023-09-20) Kavya, K S; Sreeja, P
Characterization and bioefficacy of Beauveria bassiana RB PTB on rice bug Leptocorisa sp.
(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025-01-31) Aany, M; Sreeja, P
Microbial control is a safer alternative to chemical pesticides and a potential tool in eco-friendly pest management. Identification and characterisation of indigenous isolates which are more virulent than exotic strains is important for developing potential entomopathogens for pest management. Beauveria bassiana RB PTB is a new indigenous isolate obtained from rice bugs from Pattambi, Kerala and was identified as a new isolate of B. bassiana (Bals.) Vuill. (Ascomycota: Hypocreales) based on molecular and morphological characters. The present study entitled “Characterization and bioefficacy of Beauveria bassiana RB PTB on rice bug Leptocorisa sp.” was conducted at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, during 2022-2024, with the objective to characterize and evaluate the pathogenicity of B. bassiana RB PTB to hemipteran pests and its compatibility with pesticides. Morphological characterization of the isolate revealed that the conidiogenous cells were densely clustered with swollen stalk, consisting of sub-globose to flask shaped venter, zig-zag shaped denticulate rachis. Conidia was hyaline, smooth walled, globose to sub- globose, with a rounded and slightly pointed base with size of 3.38 µm × 2.53 µm, hyphal width of 3.44 µm. To identify the suitable medium, for the optimum growth of B. bassiana RB PTB, cultural characteristics like colour, shape, texture, and growth rate of the mycelium were studied in five different media viz., Sabouraud Maltose Agar and Yeast (SMAY), White media (NIPHM), Czapek Dox Agar (CDA), Sabouraud Dextrose Agar (SDA), and Potato Dextrose Agar (PDA). SMAY medium favoured optimum growth of B. bassiana RB PTB with mean colony diameter of 5.20 cm at 14 DAI and colonies were pure white, woolly and densely floccose with pale yellow colour on the reverse side. The optimum temperature for the growth of B. bassiana RB PTB, was 27℃ which recorded a mean colony diameter of 5.25 cm at 14 DAI. The optimum pH for the growth of B. bassiana RB PTB was identified by culturing the fungus in SMY broth under various pH viz., 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, and 9.5 and a slightly acidic pH of 6 yielded the highest spore count of 7.65×108 spores mL-1. The infectivity of B. bassiana RB PTB to hemipteran pests was assessed by topical application of spore suspension at a concentration of 1×108 spores mL-1. Host range studies revealed that B. bassiana RB PTB was infective to pod bug, Riptortus pedestris F., brinjal mealybug, Coccidohysterix insolita Green, cowpea aphid, Aphis craccivora Koch, white fly, Bemisia tabaci Gennadius, and the brown planthopper, Nilaparvata lugens with a mortality from 40 to100 per cent at 120 HAT. Safety of B. bassiana RB PTB to non-target organisms viz., predators (Micraspis discolor and Tetragnatha mandibulata), parasitoids (Goniozus nephantidis, Trichogramma chilonis and T. japonicum) and productive insect (Apis cerana indica) were assessed. It was found safe to all predators and parasitoids except T. mandibulata with 33.33 per cent mortality. B. bassiana RB PTB was infective to Apis cerana indica, with 100 per cent mortality at 120 HAT. To evaluate the bioefficacy of B. bassiana RB PTB on rice bug, Leptocorisa acuta, a multiple dose bioassay was carried out with concentrations ranging from 103 to 108 spores mL-1. The effective concentration was identified as 1×108 spores mL-1 with the highest mortality of 100 per cent at 120 HAT and lowest LT50 value of 1.63 days. A comparative bioefficacy of indigenous entomopathogenic fungal isolates viz., B. bassiana RB PTB, B. bassiana VKA 01, and Lecanicillium saksenae were tested against third instar nymphs and adults of L. acuta. Spore suspension of B. bassiana @ 1×108 spores mL-1 recorded 100 per cent mortality at 96 HAT, while the corresponding mortality was observed in L. saksenae and B. bassiana (VKA 01) at 120 and 144 HAT respectively, whereas in adult rice bug B. bassiana RB PTB and L. saksenae recorded 100 per cent mortality at 144 HAT. The compatibility of B. bassiana RB PTB with selected fungicides and insecticides were assessed in vitro using poisoned food technique. Among tested fungicides, copper hydroxide 77 WP at 0.1 per cent was found to be highly compatible with mean colony diameter of 5.15 cm at 14 DAI and 0.96 per cent inhibition, while carbendazim 50 WP (0.1%), mancozeb 75 WP (0.2%), hexaconazole 5 EC (0.2%) and tebuconazole 50% + trifloxystrobin 25% 75 WG (0.04) were incompatible with 100 per cent growth inhibition. Among insecticides, flubendiamide 20% WG and thiamethoxam 25% WG were compatible with 10.58 and 12.02 per cent inhibition with colony diameter 4.65 and 4.57 cm respectively, while acephate and malathion recorded 66.35 and 59.61 per cent inhibition. In conclusion, B. bassiana RB PTB was found to be a promising isolate against hemipteran pests and safe to natural enemies in rice ecosystem. This novel isolate can be uplifted as a potential candidate for pest management.
Ecological engineering for pest management in rice Oryza Sativa L
(Department of Agricultural Entomology, College of Agriculture , Vellanikkara, 2024-03-15) Meera Krishnan; Sreeja, P
Ecological 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 strategies
Mycotoxins and enzymes of entomopathogenic fungus Lecanicillium saksenae (Kushwaha) kurihara and sukarno and their bioefficacy on crop pests
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2020) Sreeja, P; Reji Rani, O P
Screening medicinal plants for antihelminthic properties against different life stages of banana burrowing nematode radopholus similis [Cobb,1893] thorne 1949
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1996) Sreeja, P; Job Sathyakumar Charles
Experiments were conducted at the department of Entomology, College of Horticulture, Vellanikkara to screen medicinal plants for antihelminthic properties against the infective stages of banana burrowing nematode R. similis. The effect of aqueous extract of different parts of 20 medicinal plants were treated at four dilutions and three exposure times. Nematicidal and nematostatic properties of these extracts were studied using the nematode culture developed on carrot callus. The study resulted in the following findings. 1. Extracts of A. indica and G. pentaphylla were highly nematicidal to infective stages of the nematode at all the tested doses. K. pinnata was significantly effective at all the tested doses except 1:40. P. longum resulted in significant mortality at all the tested doses against larval stages whereas only 1:5, 1:10 and 1:20 dilutions were effective against adult stages. Besides nematicidal effect 1:20 and 1:40 dilutions of G. pentaphylla and K. pinnata exhibited nematostatic effects. 2. Leaf extract of M. oleifera and M. piperita at 1:5 and 1:10 dilutions showed significant nematostatic effects against both larvae and adults. P. betle extract was equally effective at the three dilutions. 3. Leaf extracts of C. angustifolia, A. squamosa and L. inermis were not effective at all tested doses. 4. Fruit extract of M. azedarach was nematicidal at all the tested dilutions of 1:5, 1:10, 1:20 and 1:40. But extract of C. papaya was ineffective. 5. Seed extract of C. viscosa expressed nematostatic property at 1:5 and 1:10 dilutions against adult stages, but it was ineffective against larval stages. Treatment with seed extract of E. scandens was ineffective. 6. Rhizome extract of C. rotundus was equally effective against infective stages in causing mortality at 1:5, 1:10 and 1:20 dilutions. Besides nematicidal effects, the extract exhibited significant nematostatic effect. A. calamus extract was nematostatic at 1:5 and 1:10 dilutions. 7. Root extract of I. tinctoria was nematostatic at 1:5, 1:10 and 1:20 dilutions against both larvae and adults. In addition to immobility, it resulted in the death of adult nematodes at 1:5 and 1:10 dilutions. Extract of S. indicum showed significant nematostatic effect at 1:5, 1:10 and 1:20 dilutions against larval stages. But it was effective only at 1:5 and 1:10 dilutions against adult stages. 8. Plant extract of E. hirta expressed nematicidal property at 1:5, 1:10 and 1:20 dilutions against larval stages, but the same was effective only at the two lower dilutions against adult stages