1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2023-04-12) Gayathri, P S; Nisha, M SThe research work entitled “Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd” was carried out at Department of Entomology, College of Agriculture, Vellayani during 2020 to 2022. The objectives were to test the pathogenicity of entomopathogenic nematodes (EPNs) and to evaluate the effective EPN formulation against cucumber moth, D. indica in bitter gourd. The pathogenicity of two strains of entomopathogenic nematodes viz. Heterorhabditis indica Poinar and Steinernema carpocapsae Weiser were assessed against 3rd instar larvae of D. indica and Henosepilachna septima Dieke. Three different formulations viz. sponge, talc and alginate gel of the effective EPN strain were prepared and stored up to 11 weeks. Then, the survival percentage and virulence of infective juveniles (IJs) in each formulation was evaluated. A pot culture study was also conducted to evaluate the pathogenicity of effective EPN formulation against D. indica in bitter gourd. In the pathogenicity test, H. indica @ 100 IJs recorded highest mortality percentage of 42.50 for D. indica and 40.00 for H. septima at 24 Hours After Treatment (HAT). No mortality was observed for S. carpocapsae at all the concentration levels (10, 20, 50 and 100 IJs) for D. indica at 24 HAT. At 48 HAT, hundred per cent mortality was recorded only for H. indica at 100 IJs and it was on par with H. indica at 50 IJs. Both H. indica and S. carpocapsae at 50 and 100 IJs showed hundred per cent mortality at 60 HAT. All treatments showed hundred per cent mortality at 72 HAT. The number of IJs emerged from cadavers were slightly more for H. indica than S. carpocapsae for the same concentration of IJs. From the 1st experiment, H. indica was found to be more effective than S. carpocapsae against D. indica and H. septima. Therefore, survival percentage of IJs of H. indica were evaluated in different formulations. Highest survival percentage (100 per cent) was observed in alginate gel formulation in 1st week and it was on par with talc formulation up to 2 weeks. More than 50% survival of IJs was observed upto 8 weeks in alginate gel, 6 weeks in talc, 5 weeks in sponges and 3 weeks in water. 112 Results on virulence of IJs in different formulations revealed that IJs from alginate gel recorded mortality percentage ranging from 32.50 to 100.00 and 0.00 to 23.33 in 1st and 11th week of storage respectively against D. indica. It was statistically on par with freshly harvested juveniles at 72 HAT up to 5th week of storage. The next best formulation was found to be talc which was on par with freshly harvested juveniles at 72 HAT up to 4th week of storage. In the pot culture study, it was observed that the mortality of D. indica caused by IJs from alginate gel-based formulation of H. indica @ 4g L-1 (42.22 and 68.88) and talc- based formulation of H. indica @ 20g L-1 (40.00 and 68.88) was superior to talc-based formulation of Beauveria bassiana @ 2% (26.66 and 62.22) and neemazal 1% @ 0.2% + tween 80 (1%) (17.77 and 42.22) at 1 and 3 DAT respectively. The effect of H. indica was on par with talc-based formulation of B. bassiana @ 2% and neemazal 1% @ 0.2% + tween 80 (1%) at 5 and 7 DAT. At the same time, the highest mortality (100 per cent) was obtained for chlorantraniliprole 18.5SC@ 30g a.i. ha-1. The damage caused by D. indica ranged from 16.92 to 34.99 in alginate gel-based formulation of H. indica @ 4g L-1 and 19.97 to 41.74 in talc- based formulation of H. indica @ 20g L-1. Its effect on damage of leaves was on par with talc-based formulation of B. bassiana @ 2% of damage percentage 28.57, 40.21 and 41.00 at 3, 5, and 7 DAT respectively. Effect of H. indica formulations on the emergence of Bactrocera cucurbitae (Coquillett) from soil was studied under in vitro. Soil treated with alginate gel-based formulation of H. indica @ 4g L-1 and talc- based formulation of H. indica @ 20g L-1 recorded 16.66 per cent emergence of B. cucurbitae and its effect was on par with chlorantraniliprole 18.5SC@ 30g a.i. ha-1. Based on the present study, it can be concluded that H. indica can be stored in formulations viz. alginate gel and talc for better shelf life and it can be used as a biocontrol agent against D. indica, H. septima and B. cucurbitae in bitter gourd.Item Behavioural response of cucumber moth Diaphania indica (Saunders) (Lepidoptera:Pyralidae) towards select host plant extracts(Department of Entomology, College of Agriculture,Vellayani, 2024-02-09) Geethu Gopakumar.; Vijayasree, VAn investigation entitled “Behavioural response of cucumber moth Diaphania indica (Saunders) (Lepidoptera: Pyralidae) towards select host plant extracts” was conducted at the Department of Entomology, College of Agriculture, Vellayani during 2021-2023 with an objective to evaluate plant extracts and synthetic volatiles for the behavioural and electrophysiological responses of D. indica and identify the components of the plant extract. The plants evaluated in the study were Momordica charantia L, Trichosanthus anguina L., Cucumis sativus L., Coccinia grandis (L.) Voigt (wild and cultivated type), Cucumis melo var. acidulus Naudin., Solanum melongena L. and Amaranthus tricolor L. The behavioural bioassay of adult D. indica in Y-tube and modified olfactometer using plant extracts did not give any reliable response. The olfactory response of D. indica larvae was highest to C. grandis (wild) with a mean attraction of 23.33% followed by M. charantia, C. grandis and C. sativus with 10.83%, 9.17% and 8.33% attraction, respectively. In the GC-MS analysis of fresh leaf extracts, fatty acid, (Z,Z,Z)- 9,12,15-Octadecatrienoic acid (α-linolenic acid) and n-hexadecanoic acid (palmitic acid) was detected in all plant extracts except C. grandis (wild) and M. charantia, respectively. The alkane, dotriacontane was found in M. charantia, T. anguina, C. grandis (wild), A. tricolor and C. melo var. acidulus. The volatile compound benzaldehyde was identified in all samples except C. grandis (wild) and C. melo var. acidulus in headspace GCMS analysis of dried leaves. Electroantennographic studies showed gravid females are more responsive to plant extracts followed by unmated females. Gravid females showed highest response to extracts of M. charantia (0.25mV) and unmated females to C. sativus extract (0.14 mV). The synthetic volatile compounds, benzaldehyde and benzyl, alcohol when tested alone elicited the highest responses in the crude state. Among different combinations of these compounds, a mixture of 10µL of crude benzaldehyde and 30 µL of crude benzyl alcohol had the highest response (0.210 mV). This was on par with the response values of M. charantia and C. sativus extracts. While evaluating synthetic compounds for behavioural responses, a mixture of plateiiiiiii that D. indica shows a considerable electrophysiological, oviposition and feeding preference for M. charantia and C. sativus compared to other host plants. Linolenic acid, palmitic acid, dotriacontane and benzaldehyde were identified as common components in these plants which have reported kairomonal properties. The kairomonal property of benzaldehyde in combination with benzyl alcohol was proved in this study.Item Development of formulations from Samadera indica Gaetrn. for the management of leaf feeding pests in snake gourd(Trichosanthes anguina L.)(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2022) Remya, S; Nisha, M SThe study entitled ‘Development of formulations from Samadera indica Gaetrn. for the management of leaf feeding pests in snake gourd (Trichosanthes anguina L.)’ was carried out in the Department of Agricultural Entomology, College of Agriculture, Vellayani and at Council of Scientific and Industrial Research – National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Thiruvananthapuram during 2018 to 2021. Objectives of the study were exploration of anti-insect properties of bark and seeds of S. indica, identification of bioactive compounds in the effective extract, development of suitable formulations and field evaluation of the same against pumpkin caterpillar, Diaphania indica Saund and epilachna beetle, Henosepilachna septima (Dieke). Estimation of lethal doses viz., LD50 and LD90 of bark and seed extracts by probit dose analysis showed that LD50 of bark extract in hexane, acetone, ethanol extract and aqueous extract were 1.66, 1.03, 1.51 and 2.38% respectively against D. indica and 2.17, 1.95, 1.68 and 2.49% respectively against H. septima. Meanwhile, LD90 values were 6.49, 7.05, 5.24 and 7.90% respectively against D. indica and 6.82, 6.60, 6.17 and 7.85% against H. septima. In the case of seed extract, LD50 values were 1.79, 0.59, 1.03 and 1.54% respectively against D. indica and 1.63, 0.83, 1.60 and 2.43% against H. septima. LD90 values were 6.99, 5.17, 7.05 and 9.17% against D. indica and 9.53, 5.27, 7.94 and 9.02% against H. septima. Results of in vitro studies on antifeedant effect of S. indica bark extracts against D. indica showed that ethanol extract @ 5.24% exhibited the highest leaf protection of 62.79 per cent at 72 Hours After Treatment (HAT). In the case of H. septima, ethanol extract @ 6.17% resulted in 65.00 per cent leaf protection. Regarding insecticidal effect, ethanol extract @ 5.24% resulted in 93.33 per cent mortality of second instar larvae of D. indica. Meanwhile, in grubs of H. septima, ethanol extract @ 6.17% inflicted 91.67 per cent mortality. Insecticidal effect of both the extracts was found to be statistically on par with chemical check (Malathion 50 EC 0.1%). With regard to insect biology, there was increase in larval duration (15.00 days), pupal duration (5.33 days), reduction in pupal weight (0.19 g) and reduction in adult longevity (4.33 days) in D. indica, whereas in control, larval and pupal period were 9.67 and 2.67 days each, pupal weight was 0.31 g and longevity of adults was 7.67 days. Similar trend was observed in H. septima. Among various extracts from S. indica seeds, acetone extract @ 5.17% resulted in the highest leaf protection of 74.41 per cent in D. indica and acetone extract @ 5.27% exhibited 71.79 per cent leaf protection in H. septima. With respect to insecticidal effect, acetone extract @ 5.17 and 5.27% each caused 86.67 per cent mortality in D. indica and H. septima respectively. Considering biology of the insects, there was prolongation in larval period to 17.00 days, pupal period to 8.67 days, reduction in pupal weight to 0.25 g and reduction in adult longevity to 6.33 days in D. indica as against larval period of 12.67 days, pupal period of 5.33 days, pupal weight of 0.35 g and adult longevity of 7.67 days in control. Similar was the trend with H. septima also. A comparison between LD50 and LD90 of bark and seed extracts pointed out that seed extract contained more potent compounds with insecticidal properties. Hence, seed extract was taken for further studies. Chromatographic fractions from acetone extract of seeds @ 5% exhibited mean leaf protection of 91.83 per cent in D. indica and 85.71 per cent in H. septima. Meanwhile, there was mortality of 73.33 per cent in both the pests. Analysis of chromatographic fractions revealed the presence of quassinoids viz., samaderin A, samaderin B, samaderin C and cedronin in the seed extract. Molecular structures were elucidated to confirm the identity of the compounds. Two formulations of S. indica seed extract were prepared by mixing seed extract, emulsifier and distilled water in different proportions. Formulation A contained acetone extract of S. indica seed, tween 80 and distilled water in 15: 5: 80 ratio. Formulation B was prepared by mixing seed extract of S. indica in acetone, tween 80 and span 80 (1: 1) and distilled water in 15: 5: 80 ratio. Both the formulations A and B were equally effective against D. indica and H. septima under in vitro conditions, with 80.00 per cent mortality each at 72 HAT. Safety evaluation on beneficial insects indicated that formulation A @ 1% resulted in 30.00 per cent mortality in honey bee after 24 HAT, while in A. taragamae, it was 23.33 per cent. Furthermore, both the formulations were stable under normal room temperature for six months. Formulation A @ 1% recorded 71.67 to 80.00 per cent mortality in D. indica and H. septima from the day of preparation till sixth month of storage. Meanwhile, formulation B @ 1% resulted mean percentage mortality of 70.00 and 75.00 per cent in D. indica and H. septima. Considering the insecticidal effect under in vitro conditions and environmental feasibility, formulation A was chosen for in vivo studies. Field experiment was carried out to test the efficacy of the botanical in comparison with biopesticide and chemical at Instructional Farm, Vellayani in snake gourd (variety Kaumudi). Formulation A @ 2% was evaluated for its efficacy against D. indica and H. septima at vegetative stage and 50 per cent flowering stage. Observations were taken on pest population and percentage of damaged leaves. It can be deduced that formulation A @ 2% was as effective as neemazal @ 0.2% as evident with reduction in pest population at vegetative and 50 per cent flowering stage of the crop. With regard to reduction in leaf damage, formulation A @ 2% excelled equally as neemazal @ 0.2% at vegetative stage. The study revealed that both bark and seed extracts of S. indica exhibited feeding deterrence, insecticidal properties and caused adverse effects in the biology of D. indica and H. septima. Anti-insect properties are more prevalent in the seeds and they contained the bioactive compounds samaderins A, B, C and cedronin. Formulations containing acetone extract of S. indica seeds, tween 80 and distilled water (15: 5: 80) @ 1 and 2% each were effective against both the pests under in vitro and in vivo conditions respectively and were stable for a period of six months under room temperature. Hence, it can be concluded that formulations from S. indica can be considered as safer botanical insecticides in this era of organic farming.Item Evaluation of bacillus thuringiensis isolates against diaphania indica (saund.) (Lepidoptera:pyralidae)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2017) Janish Rose Jacob; Girija, DChemical pesticides provide significant benefit by controlling pests of agricultural crops. However, their use has increased at an alarming rate, along with proportionate increase in their adverse effect on the environment. In recent years, several insects have developed resistance towards a few pesticides due to their indiscriminate use. Several microbial agents have been used as an alternative for chemical pesticides and Bacillus thuringiensis is one among them. B. thuringiensis is a sporulating, Gram positive, facultative anaerobic soil bacterium, capable of synthesizing δ-endotoxins or Cry proteins during sporulation. Due to the insecticidal properties of these proteins, the bacterium is used against insect species of the orders Lepidoptera, Coleoptera and Diptera. More than 500 isolates of B. thuringiensis obtained from the Western Ghats of Kerala, in a DBT funded project, are being maintained in the repository of the Department of Agricultural Microbiology, College of Horticulture, Thrissur. Several microbial inoculants such as Pseudomonas fluorescens, Trichoderma viride, Beauvaria bassiana, Lecanicillium lecanii have been developed by Kerala Agricultural University but there is no formulation of B. thuringiensis. A study was conducted to develop a commercial formulation of B. thuringiensis and to evaluate its bio-efficacy against the pumpkin caterpillar, Diaphania indica (Saund.). Twenty native isolates with cent per cent mortality in previous studies were selected from the repository of the Department of Agricultural Microbiology. Morphological, biochemical and molecular characterisation of these native B. thuringiensis were carried out. The isolates showed only very slight variations in their cultural characteristics. Colonies appeared circular, creamy white with entire to undulate margin and flat elevation. The isolates showed positive reaction to starch and esculin hydrolysis, sucrose fermentation test and negative to Voges-Proskauer test. The isolates were screened for the presence of lepidopteran specific insecticidal genes, using PCR. Among the 20 native B. thuringiensis isolates, seven isolates yielded cry1 gene amplicons. None of the isolates produced cry2 and cry9 amplicons. The cry1 amplicons were further sequenced and when subjected to Blastn analysis showed homology towards cry1, cry1A, cry1Aa and cry1Ac. All the isolates have shown identity in the range of 93-96 per cent to the known cry1 genes. Thus, the presence of cry1 gene was confirmed. Based on the abundance of crystal protein and cry1 gene, three native isolates (KAU-11, KAU-474 and KAU-2189) were further selected for laboratory bioassay against the lepidopteran pest, D. indica. Among the native isolates, KAU-2189 showed highest per cent morality and was further selected for liquid formulation studies. Suitability of three media (soy flour broth, coconut water broth and T3 broth) was assessed based on the population and spore count at 0 h, 72 h and 96 h after inoculation. Coconut water yielded higher population than the standard medium (T3 broth). Spore count of B. thuringiensis in coconut water and T3 were statistically on par. Thus, coconut water served as the best among the tested substrates for B. thuringiensis production and this was further used for the liquid formulation. Bio-efficacy of the liquid formulation was evaluated in pot culture experiment against D. indica using little gourd (Coccinia indica) as the test crop. Btk (ABTEC), a commercial formulation was used as standard. The higher per cent mortality was recorded for the formulations containing KAU-2189 in coconut water broth and HD-1 in coconut water broth and both were statistically on par with each other. Minimum leaf damage was also recorded in treatments with these formulations and was statistically on par with each other. Shelf life studies of liquid formulations indicated that both population and spore count decreased from fourth month onwards. The study revealed that the native isolates have the potential to be developed into a biopesticide. Coconut water could be used as an ingredient for low cost liquid formulation. Further evaluation under field conditions is required to confirm the efficiency of KAU-2189 as a biopesticide.