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Central Agricultural University, College of Post Graduate Studies in Agricultural Sciences, Umiam
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ThesisItem Open Access Insect pest complex of radish and eco-friendly management of major insect pests in Meghalaya(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal, 2023-10) Rai, Sabina; Patra, SandipRadish (Raphanus sativus L.) is one of the most popular root crop vegetables grown throughout the year which belongs to the family Brassicaceae. Insect pests are the most important crop limiting factor. In Meghalaya there are numerous insect pests infesting radish, however, no proper information on the insect pests complex as well as effective control measures have been studied in this area. Therefore, the present study was conducted to study the insect pests complex of radish, population dynamics and eco-friendly management of major insect pests. The experiment was conducted at Entomology Research Field, Division of Crop Science, ICAR Research Complex for NEH Region, Umiam, Meghalaya. Radish (Var: Japani white long) was sown at five different sowing dates in a randomized block design (RBD) with four replications. A total of 17 insect species were recorded, out of which 13 species were observed as insect pests, and 4 were natural enemies. Insect pests recorded belongs to 4 orders and 7 families viz., 6 Coleoptera, 3 Lepidoptera, 3 Hemiptera and 1 Hymenoptera. Among the insect pests, striped flea beetle (Phyllotreta striolata Fab.) and crucifer flea beetle (Phyllotreta cruciferae Goeze) were found the most damaging pest and considered to be the major insect pests of radish in this region. Population dynamics showed that number of striped flea beetle ranged from 0.67 to 12.60 beetles/plant during different observations with peak population on third week of January i.e. 3rd SMW whereas population of crucifer flea beetle ranged from 0.27 to 6.47 beetles/plant with peak population on third week of January i.e. 3rd SMW. Striped flea beetle and crucifer flea beetle population were negatively significant with maximum, minimum and average temperature. The first and second sowing recorded less infestation of insect pests and highest yield 266.53q/ha and 264.60q/ha, respectively and the lowest yield was obtained from late sowing i.e. 5th sowing (230.70q/ha). Cypermethrin was found to be most effective treatment against striped flea beetle with 1.98 beetle/plant and 81.06% reduction over control and crucifer flea beetle with 1.06 beetle/plant and 78.75% reduction over control. Amongst the bio-pesticide Metarhizium robertsii, neem oil, and Beauveria bassiana was found effective in reducing beetle population over untreated control. The highest yield of radish 328q/ha (with leaves) and 231.70q/ha (without leaves) was observed in cypermethrin treated plot. The present study concludes that early sowing during rabi season i.e. mid-October to mid-November maybe sown to avoid the severity of insect pests. Cypermethrin may be used for effective management of flea beetles. Among biopesticides, Metarhizium robertsii, neem oil and Beauveria bassiana may be employed safely for organic management of these pests of radish.ThesisItem Open Access Effect of different temperatures and plant oils on Bruchid, Callosobruchus maculatus (Fab.) and Curculionid, Sitophilus zeamais (Mots.)(2018-07) Sravani, Balguri Lavanya; Thakur, N. S. AzadIn recent times, paramount importance is given on good production practices, efficacious crop protection and handling for higher and better yield, sufficient for meeting the needs of increasing population. But little or no emphasis is given on effective storage requirements with minimum post-harvest losses. One of the crucial reason behind this losses are stored grain insect pests. They are unnoticeable when present in small numbers due to their cryptic behaviour. In congenial conditions, their population can go beyond unmanageable level. Moreover, emerging threats of climate change due to rise in global temperature is a probable reason for aggravating the congenial conditions. Henceforth, there is a need to understand the biology of stored grain pest at different temperatures suitable for development of higher population. Therefore, a study on bruchid, Callosobruchus maculatus (Fab.) and curculionid, Sitophilus zeamais (Mots.) at four different temperatures i.e., 20, 25, 30 and 35 °C was conducted. The duration of development decreased with the increase in temperature. At 20 °C, both the bruchid and curculionid had a longer incubation period (7.01 days; 6.65 days), grub period (21.01 days;35.91 days) and pupal period (6.02 days; 12.03 days), respectively, which was reduced at 35 °C i.e., incubation period (4.35 days; 5.33 days), grub period (12.07 days; 17.95 days) and pupal period (3.41 days, 4.25 days), respectively. The longest longevity period for bruchid and cuculionid male (11.65 days; 93.02 days) was recorded at 20 °C, whereasshortest duration of 7.50 days, 71.65 days, respectively, was recorded at 35 °C. Similarly, female adult longevity of bruchid and curculionid, longest longevity period (13.61 days;125.43 days) was observed at 20 °C, and shortest at 35 °C (8.76 days; 80.42 days), respectively. Bruchid and curculionid had the longest pre-oviposition period of 2.60 hrs and 3.28 days at 20 °C which reduced to 1.33 hrs and 1.87 days, respectively at 35 °C. In case of bruchid, longest oviposition period of 8.61 days was observed at 20 °C and shortest (6.62 days) at 35 °C whereas in curculionid, the longest duration of 80.33 days was recorded at 30 °C and shortest duration (63.93 days) at 20 °C, respectively. However, the fecundity of 103.96 and 90.47 eggs/female was found highest at 30 °C in bruchid and curculionid, respectively. In order to protect the produce from being lost both qualitatively and quantitatively, effective management practices should to be ascertained. Plant oils being one of those, is a boon over pesticides with regard to cost effectiveness, local availability, low persistence, high efficiency, low mammalian toxicity besides environmental safety. Thus, the present investigation was carried out to identify the effective plant oils against C. maculatus and S. zeamais. Eight plant oils i.e., rosemary, blackpepper, sweetflag, sacred tulsi, citronella, peppermint, eucalyptus and pine were evaluated at adose of 2 ml plant oil/kg of seed where seeds without any plant oil served as control. It was observed that the adult mortality of bruchid and curculionid increased with the increase intime period from 24 to 96 hrs. At 96 hrs after treatment, among these oils, rosemary oil and peppermint oil exhibited highest per cent adult mortality by 67.11 % and 69.85 % against bruchid and curculionid, respectively. However, the least mortality of 34.40 % and 11.81 % was yielded by calamus oil and pine oil against bruchid and curculionid, respectively. Plant oil treatments assessed were significantly superior to control. This study concluded that increase in temperature caused higher population build up and greater population dynamics among stored grain pests in shorter duration. Among the plant oils tested, rosemary oil and peppermint oil were highly effective against bruchid and curculionid, respectively, which can be utilized in the stored grain pest management strategies. Further research can be carried out on aspects such as compatibility studies among various plant oils and cost effective technology for incorporating them in storage godowns for safe and longer efficiency.ThesisItem Open Access Studies on various histological changes in haemocytes associated with NPV infection in Helicoverpa armugera (Hubner)(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal, 2018-10) Singh, Yengkhom Suraj; Ningthoujam, KennedyLaboratory rearing of insects using synthetic diets is a better option for knowing its biology under controlled conditions. Successful rearing becomes the first priority to study its life history and nourishing behaviour using synthetic diets. Many researchers attempted to rear H. armigera under laboratory conditions using synthetic diets. While its haemocytes are very vital components of the insect immune system and are biochemically very sensitive having multiple functions such as nodule formation, phagocytosis and encapsulation as defence mechanism, synthesis and transport of nutrients and hormones for proper growth and wound healing by way of connective tissue formation. Therefore, keeping these facts in mind, in the present investigation, study was done on some of the important biological parameters of this insect by rearing on the semi-synthetic diets based on four locally available pulses viz.,chickpea, green gram, pea and black gram and comparing with chickpea leaves used as control. The larvae obtained from the culture were used to study the changes in their Total Haemocyte Count (THC) and Differential Haemocytes Count (DHC) when they were NPV infected with 0.2 ml of 2x105 occlusion bodies (OB) ml-1 at various stages at 5, 8 and 10 days old. Results revealed that the fitness index on chickpea (1.48) showed the highest followed by pea (1.23) and the lowest on control (0.80) and proved that chickpea based semi-synthetic diet was the best for mass rearing of H. armigerawhile pea-based diet could also be used as substitute. DHC showed six identified cells-prohaemocyte, plasmatocytes, granulocytes, spherulocytes, adepohaemocytes and oenocytoids and another four unidentified cells. Among the identified cells oenocytoids did not show any involvement in defence mechanism. THC showed that the effect of NPV infection was more in younger larvae.ThesisItem Open Access Effect of plant extracts and essential oils on major Lepidopteran pests of cruciferous crops(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal, 2018-10) Devi, Pebam Inija; Firake, D. M.Vegetable production is an important source of income to the farmers of NE region. The lepidopteran pests are one of the most important constraints in vegetable production. Leaf defoliators, Spodoptera litura, Plutella xylostella and Pieris brassicae are three important pests attacking cruciferous plants. Fresh eggs of the major defoliating insect pests on vegetables viz., leaf eating caterpillar, S. Litura (Fabricius), the large cabbage white butterfly, P. brassicae (Linnaeus) and the diamondback moth, Plutella xylostella (Linnaeus) were collected from the unsprayed vegetable field of Division of Crop Protection (Entomology), ICAR Research Complex for NEH Region, Umiam, Meghalaya, during the year 2017-18 and further reared inlaboratory for different experiments on castor, cabbage and knol khol plants, respectively. Plant extracts from different plants viz., Vitex negundo, Curcumaangustifolia, Parkia roxburghii and Fleminga vestita were collected from Division of Crop Protection (Entomology). Essential oils viz., Cymbopogon citratus, Piper nigrum, Mentha piperita, Occimum basilicum and Rosmarinus officinalis were collected from ICAR, Umiam and some are purchased commercially. The test insects were exposed (In contact and oral toxicity) to plant extracts/oils in 2nd instar larval stage (i.e. most active feeding stage). Toxicity test were conducted by standard protocols: Topical application technique: Direct contact (fixed dose) (Mclaughlin et al., 1998) and Leaf dip method: Oral toxicity (Hoskins and Craig., 1962). Concentrations of the extracts were determined on the basis of preliminary experiments on the test insects. Seven concentrations (including control) of each extract were tested against test insects.Overall results revealed that, in topical application technique, LC50 value of O.basilicum was observed to be 0.09 per cent and V. negundo 1.99 per cent, against the caterpillars (2nd instar) of S. litura at 72 hrs; whereas it was found to be 0.28 per cent and 1.59 per cent on P. xylostella, respectively. In case of P. brassicae, LC50 of Pipernigrum oil and V. negundo extract was observed to be 0.02 per cent and 0.71 per cent. When the caterpillars of S. litura, P. brassicae and P. xylostella were topically treated with sub-lethal doses, the significant variation was observed in larval and pupal weight, their duration, per cent pupation and adult emergence. Inverse relationship was found in leaf area consumption by the caterpillars on different extracts. Food consumption was significantly reduced in treated larvae of the two pest species (S. litura and P.brassicae) compared to untreated larvae in control. From the present study, it can be concluded that, n-hexane fraction of Vitex negundo and essential oils of Ocimumbasilicum and Piper nigrum are most effective against major cruciferous defoliators and thus, they can be formulated and further evaluated for their potential under field conditions in organic farming.ThesisItem Open Access Assessment of toxicity of bio-pesticides to the Indian honey bee, Apis cerana indica (Fabricius) in oilseed Brassica(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal, 2018-10) Kumar, Challa Girish; Firake, D. M.Rapeseed and Mustard is the second most important edible oilseed crop in India after Soybean and accounts for 27.8 per cent of the total oilseeds produced in the country.The crop shares around one-third of the India's oil production, making it the country’s key edible oilseed crop. It is an open pollinated crop which is heavily pollinated by honey bees. Recently declines of various pollinators have been reported. Biopesticides are the integral part of the organic agriculture and they are considered to be safe to the natural enemies and pollinators. However, several studies indicated that bio-pesticides may also be harmful to the pollinators. It is essential to assess the risk of bio-pesticides to the foraging honey bee in oilseed brassica to promote higher yield with efficient pest control. Therefore, commonly used bio-pesticides were evaluated for their safety to the Indian honey bee, Apis cerana indica (Fabricius). The study was conducted in two tier approach i.e. laboratory and field conditions. For in vitro studies, target insects were collected from entomology farm at ICAR-NEH, Umiam and reared according to standard protocols. LC50, LC90 and LD50 values were determined for the insect pests and honey bees, to assess the risk against honey bees. Laboratory studies showed that LC50’s of pesticides to the honey bee was in the order of Nomuraea rileyi (100) > B. bassiana (4.798) > Bt var k (1.670) > azadirachtin (1.642) > annonin(1.221) > cyantraniliprole (0.056) > spinosad (0.006) > imidacloprid (0.005). Acute toxicity data of insect pests and honey bee were used to determine three essential risk assessment criteria’s viz., selectivity ratio, probit substitution method (%) and hazard ratio/risk quotient. Based on these three risk assessment criteria’s, azadirachtin, annonin, B. bassiana and Bt var kurstaki were found selective, but slightly to moderately toxic to the honeybee; whereas, spinosad, cyantraniliprole and imidacloprid were found non-selective and dangerous to the bees. N. rileyi was found selective and absolutely harmless to the bees. Relative abundance, foraging rate, foraging speed and yield in different treatments were considered to know the influence of biopesticides on foraging activity in vivo. Relative abundance, foraging rate and foraging speed of honey bees were significantly affected in different treatments even up to 2 days of spraying. Among bio-pesticides, deterrence/repellent effect was however severely observed in annonin and spinosad treatments up to 2 days. Significantly higher yield was obtained in azadirachtin (1.43 t/ha) and annonin (1.22 t/ha) treated plots. This study concludes that, except spinosad remaining bio-pesticides were safe to the foraging bees, however considering efficient pest control and higher yield, the neem oil based formulation of azadirachtin and annonin could be efficiently used in Integrated Pest and Pollinator Management Programme (IPPM) in oilseed brassica’s. Owing to its harmful effect on bees, use of spinosad 2.5 SC should be discouraged especially during the flowering period in oilseed brassicaThesisItem Open Access Bioefficacy and dissipation of imidacloprid and thiacloprid in/on chilli (Capsicum annuum L.)(2018-10) Sutnga, Baiamon; Patra, SandipChilli (Capsicum annuum L.) is an important vegetable and spice of India. India is the largest producer of chilli in the world. Although, its share in global production is high, there are still a number of factors that limits its production and productivity and one being infestation by insect pest. In chilli, sucking pests are a major problem and they can cause 60 to 75% loss in yield. Therefore, a study was undertaken to assess the bioefficacy of some new insecticides (imidacloprid and thiacloprid) against chilli aphid, Aphis gossypii Glover. Six treatments (imiacloprid17.8SL @ 25 and 50 g a.i. ha-1, thiacloprid 21.7SL @ 54 and 108 g a.i. ha-1 and dimethoate 30EC @ 300 and 600 g a.i. ha-1) were applied along with control with the initiation of aphid population consisting three replications. Pre-treatment population of aphids was taken one day before the spray and subsequently observation was recorded on 1, 3, 7, 10 and 14 days after insecticide spray. The dissipation pattern of imidacloprid at 25 g a.i. ha-1 and 50 g a.i. ha-1 and thiacloprid at 54 g a.i. ha-1 and 108 ga.i/ha were also studied by collecting chilli fruits and soil samples at 0, 1, 3, 5, 7, 10and 15 DAS. Immediately after collection of samples extraction was done followed by clean up and analysis using High Performance Liquid Chromatography (HPLC). The bioefficacy study revealed that the overall mean reduction of chilli aphid population was highest in imidacloprid at 50 g a.i. ha-1 with 80.33% reduction. The maximum fruit yield was also recorded in imidacloprid @ 50 g a.i. ha-1 with 86.10 q/ha. Dissipation study revealed that the initial deposit of imidacloprid at 25 and 50 g a.i. ha-1 in fruit samples were 1.20±0.102 and 1.74±0.103 mg/kg respectively which dissipated to BDL on 10th DAS. Half-life values of imidaclorid in chilli were 1.75 and 1.87 days at single and double dose, respectively. A waiting period of 4.52 and 5.84 days were calculated for single and double doses, respectively. In thiacloprid, an initial deposit of 1.10±0.036 and 1.84±0.034 mg/kg was observed on chilli fruits at both recommended dose and double the recommended dose, respectively. The residues were dissipated to BDL on7th DAS. The half-life and waiting period of thiacloprid in chilli at single and double doses were worked out to be 1.44 and 1.46 days and 8.33 and 9.53 days, respectively.ThesisItem Open Access Development of DNA barcodes for major insect pests and natural enemies of Cucurbitaceous crops in mid hills of Meghalaya(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal, 2018) Pongen, Arensungla; Behere, G. T.The cucurbitaceous crops (cucumber, pumpkin, gourds and chow-chow) are of tremendous economic importance and are cultivated throughout the world from tropical to sub-temperate zones. Insect pest infestations in cucurbits bring about heavy losses depending upon species and the season in different parts of the world. Correct identification of insect pest is a prerequisite step before undertaking any control measures. DNA barcoding has appeared to be a useful tool in resolving the issues related to identification of taxonomically difficult insect species. Limited information is available on insect biodiversity and DNA barcodes (insect pest & Natural enemies) in cucurbitaceous crops. Therefore, efforts were made to study the biodiversity of insects and to develop DNA barcodes for major insect pest and natural enemies present in cucurbitaceous crops in mid hills of Meghalaya. A total of 41 insect species belonging to six insect orders viz., Coleoptera (17), Hemiptera (8), Diptera (6), Hymenoptera (5), Lepidoptera (4), and Araneae (1) were collected and identified. There were a total of 31 insect pest and 11 natural enemies recorded. The insect species viz., Aulacophora foveicollis, Aulacophora lewisii, Bactrocera cucurbitae, Bactrocera tau and Henosepilachna pussillanima were found to be major pests of cucurbits in this region while the common natural enemies were Coccinella septempunctata, Micrapis sp. and Oenopia kirbyi. The collected species were identified based on established taxonomic keys, by taxonomists and/or molecular basis. DNA was successfully extracted from multiple specimens of 41 insect species and molecular assays were also undertaken for presence of Wolbachia infection. The DNA barcodes were successfully developed for 33 species by sequencing partial Cytochrome oxidase I (COI) gene of mitochondrial DNA. The molecular identity of the insect species was established through BLAST-n NCBI. The species level identity was developed for 23 species and remaining 10 was identified upto genus level due to absence of matching molecular data at NCBI. All the analyzed sequences have been deposited to International Gene Bank (NCBI) with accession numbers MH198024 to MH198037 and MH395845 to MH395863. The molecular identity of 3 species viz., Malcus sp., Paridea sp. and Coridius sp. were established for the first time and the partial COI sequences of these species were added to the GenBank nucleotide database collection. The insect pests Leptoglossus gonagra, Aulacophora lewisii, Bactrocera carambolae, Arthrotus flavocincta, Spilarctia sp., Spaniocelyphus falcatus, Tiracola plagiata, Kolla paulula, Malcus sp., and Paridea sp., have been reported for the first time in cucurbit crops from Northeastern India; Bactrocera cilifera, a recently discovered fruit fly in India has been reported for the first time in Meghalaya. This study has resulted in 80 percent successful identification of insect pest and its natural enemies. The comprehensive taxonomical and molecular database developed in this study for a total of 33 species observed in cucurbitaceous crop ecosystem could be used as diagnostic guide at both morphological and molecular level.ThesisItem Open Access Insect biodiversity and seasonal incidence of major insect pests in wheat (Triticum aestivum L.) ecosystem in mid-hills of Meghalaya(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University-Imphal, 2019) Nadon, Wankitkupar Fernando; Thakur, N. S. AzadStudies on “insect biodiversity and seasonal incidence of major insect pests in wheat ecosystem in mid hills of Meghalaya” was conducted in 2018-19 Rabi season at the experimental farm at College of Post Graduate Studies in Agricultural Sciences (CPGSAS), CAU(I), Umiam, Meghalaya. Wheat crop was raised in 9 different plots with three sowing dates. Field surveys, observations, collection, identification and preservation of insect species was done in the cropping season. A total of 58 insect species recorded to be associated with wheat crop. The insects belonged to 32 families of 8 orders, viz., Diptera (16 species), Coleoptera (13 species), Hemiptera (11 species), Hymenoptera (9 species), Orthoptera (4 species), Lepidoptera (3 species), Odonata (1 species) and Neuroptera (1 species). The collected insect species were categorized into pests (32 species), natural enemies (24 species), pollinators (1 species) and visitors (2 species). Insect pests were further divided into major and minor pests, having two species (Rhopalosiphum padi L. and Sitobion avenae F.) and 30 species, respectively. Minor pests comprised of 5 orders which belonged to 16 families. Natural enemies comprising of 6 orders and 12 familes were classified as predators (14 species), parasites (5 species) and parasitoids (5 species). Only one species of pollinators, viz., Plecia nearctica (Hardy) and two species of occasional visitors, viz., Pieris brassicae nepalensis (Doubleday) and Bactrocera dorsalis (Hendel) were recorded. R. padi population was found increased in the early crop growth stage, viz., seedling and tillering stages and was maximum in November second week 2018, with 13.20 aphids per plant, whereas S. avenae population was maximum during the earhead emergence until ripening stages with 35.39 aphids per earhead on 28th February 2019. The study on correlation between pest incidence and weather factors showed that minimum temperature (r= 0.50*) and evening relative humidity (r= 0.45*) had significant positive effect on R. padi and S. avenae population, respectively. Regression co-efficient (R) was also worked out. Impact of dates of sowing on major pest incidence on wheat revealed that R. padi population was maximum on the wheat crop sown first (27th October 2018) and minimum on the wheat crop sown last (17th November 2018). The infestation of S. avenae was maximum in the crop sown on 17th November 2018, whereas minimum in the crop sown on 27th October 2018 and 7th November 2018, respectively.ThesisItem Open Access Arthropod diversity in rice ecosystem with special reference to spiders in mid-hills od Meghalaya(College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University-Imphal, 2019) Nakambam, Sonali; Ningthoujam, KenedyBiodiversity is essential for sustainability of life on Earth. Terrestrial arthropods represent maximum proportion of all biotic diversity in the world. Spiders are diverse arthropods attaining seventh rank in diversity. In rice ecosystem, spider plays an important role as predators in reducing plant hoppers and leafhoppers. Biological control of insect pests through spiders is gaining importance as they are efficient in reducing pest population and also reduce the use of toxic chemical pesticides. The present study was undertaken to document diversity of arthropods in rice field. A total of 1640 individuals which come under 98 species belonging to 74 genera from 37 families represented by 9 orders falling under 2 classes viz., Arachnida and Insecta were recorded during the study period. Arthropods were collected using various methods viz., visual search, net sweeping, pitfall and rubbish trapping and use of aspirator. Of the total number of individuals collected, class Insecta formed the major group with 909 individuals, while 731 individuals were represented by class Arachnida. Under Arachnida, 41 species from 23 genera and 10 families were identified. Among the Pterygota, Exopterygota formed the largest group with majority of individuals from Hemiptera followed by Orthoptera, Odonata and Dictyoptera. Endopterygota was represented by four orders viz., Lepidoptera, Hymenoptera, Coleoptera and Diptera. In the order Araneae, Araneidae was the most dominant family represented by 6 genera with 16 number of species, followed by the family Lycosidae represented by 2 genera with 4 number of species. Data analysis based on species richness and abundance revealed that October month showed maximum index value in all the indices. A guild structure analysis of spiders revealed six feeding guilds such as orb web weavers, stalkers, ground runners, space web builders, ambushers and foliage runners. Orb weavers guild was shown as the most dominant guild which was abundantly found in the month of October when crop canopy was fully developed. Oxyopes bharatae and Pardosa sumatrana were found throughout the study period. Correlation analysis showed that Araneidae population showed positive correlation with rainfall but negatively correlated with maximum temperature and relative humidity.
