Browsing by Author "Vidya, C V"

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Bionomics and ecological management of coconut eriophyid mite
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2001) Vidya, C V; Ranjith, A M
Mother knows best: oviposition behaviour in insects
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2020) Beegam Salma, M P; Vidya, C V
Screening Amaranthus (Amaranthus spp.) genotypes for yield, quality and Rhizoctonia leaf blight
(epartment of Vegetable Science, College of Agriculture,Vellanikkara, 2026) Akhila, S; Flemine Xavier; Vidya, C V
Amaranthus (Amaranthus spp.) is a nutrient rich leafy vegetable grown in tropical and subtropical regions, especially in Southern India. It is valued as an excellent source of proteins, vitamins, dietary fiber, minerals, and bioactive compounds with antioxidant and therapeutic properties. Amaranthus is commonly referred to as the “poor man’s spinach” because of its quick growth habit, superior nutritional value, and low cultivation cost. As a C₄ photosynthetic plant, amaranthus thrives well under adverse climatic conditions, produces high yields, and serves as an ideal component of sustainable agriculture. It shows a wide range of variability for morphological and quality characters highlighting its potential for effective genetic improvement. Leaf blight disease caused by the soil borne fungal pathogen Rhizoctonia solani Kühn poses a major challenge to amaranthus cultivation. It severely reduces the crop’s yield potential and overall market quality. The disease initially appears as small, irregular creamy white spots on the leaves, which expand under humid conditions to form large translucent and light green lesions, ultimately leading to the development of shot hole symptoms. The use of chemical fungicides for the control of disease is not advisable especially for leafy vegetables due to the risk of pesticide residue accumulation. Development of resistant varieties stands out as the most efficient method for the management of the disease. The present study entitled “Screening amaranthus (Amaranthus spp.) genotypes for yield, quality and resistance to Rhizoctonia leaf blight” was undertaken at the AICRP on Vegetable Crops, College of Agriculture, Vellanikkara from 2024 to 2025 to assess the genotypes for yield and quality traits and to screen them for Rhizoctonia leaf blight. In the first experiment, forty five diverse amaranthus genotypes were evaluated in a Randomized Block Design with two replications for yield, quality and Rhizoctonia leaf blight tolerance. Substantial variability was observed in morphological, biometric, disease reaction and biochemical traits. The morphological characterization of forty five amaranthus genotypes revealed variability across majority of the recorded traits. Among the genotypes, VLKAM-42 recorded the highest yield per plant followed by VLKAM-37. Three genotypes viz., VLKAM-25, VLKAM-41 and VLKAM-42 were completely free from the Rhizoctonia leaf blight under field conditions and recorded a zero disease index (PDI) value. The genotype VLKAM-36 displayed a very low PDI (6.44) and was classified as highly resistant. High genotypic and phenotypic coefficients of variation were exhibited by the traits such as plant height, stem girth, leaf length. leaf width, petiole length, number of branches, leaf weight, stem weight, yield per plant, beta carotene, chlorophyll, carotenoid, oxalate and nitrate content. High heritability coupled with high genetic advance was recorded in most of the biometric and biochemical characters, indicating that the inheritance of these characters is mainly governed by additive gene effects. Hierarchical cluster analysis grouped the forty five genotypes into seven distinct clusters, reflecting broad genetic diversity among them. Significant positive correlations were observed between yield per plant and characters such as stem weight, leaf weight, stem girth, plant height, leaf length, petiole length and leaf width. In the second experiment, ten genotypes showing immune to moderate resistance in the field were screened in-vitro with artificial inoculation of Rhizoctonia solani. The accession VLKAM-41 remained free of symptoms. The accessions VLKAM-25, VLKAM- 36, and VLKAM-42 showed only limited lesion development. The genotypes VLKAM-34, VLKAM- 14, VLKAM-10 and VLKAM- 24 exhibited small lesions with limited expansion indicating a moderately resistant reaction. A multiple trait selection index integrating key quantitative, biochemical and disease resistance parameters, ranked VLKAM-42 as the best performing genotype followed by VLKAM-37, VLKAM-41, VLKAM-43 and VLKAM-40. These genotypes possess a combination of good yield performance, favourable biochemical traits, and disease resistance, making them promising candidates for future breeding efforts. The present study revealed a wide range of morphological and genetic variability among the amaranthus genotypes. It also identified amaranthus genotypes with stable resistance to Rhizoctonia leaf blight which can be used as valuable donor sources in the future breeding programmes for the development of leaf blight resistant varieties
Systematics of the tribes scymnini and stethorini (coleoptera: coccinellidae) from South India
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2018) Vidya, C V; Haseena Bhaskar
Family Coccinellidae, the lady beetles, belong to the superfamily Coccinelloidea of the order Coleoptera and comprises approximately 6000 described species worldwide. Tribes Scymnini and Stethorini of the subfamily Scymninae of Coccinellidae are economically important predators successfully used in the biological control programmes of sucking pests of crops. Members of Scymnini are mainly predators of aphids, mealybugs, whiteflies and scales, whereas Stethorini are specific to mites. Though the fauna of Scymnini and Stethorini in India is species rich, it is poorly studied. The present investigation on “Systematics of the tribes Scymnini and Stethorini (Coleoptera: Coccinellidae) from south India” was carried out during 2015-17. The objectives include the following: (1) taxonomy of the tribes Scymnini and Stethorini associated with sucking pests in different agricultural ecosystems of south India, (2) prepare a key to the species of Scymnini and Stethorini and (3) generate DNA barcode for different species of Stethorini. Purposive surveys were undertaken across different districts of Kerala, Karnataka and Tamil Nadu covering 47 locations and 64 crops under different agricultural ecosystems. Beetles and immature stages of Scymnini and Stethorini were collected along with the associated prey. Immature stages of Scymnini and Stethorini were reared to adults. The specimens were then mounted, labeled and preserved as per standard procedures. The beetles were dissected and the taxonomic characters viz., antenna, mouth parts, prosternum, tarsus, post coxal line, male and female genitalia were studied and illustrated. The specimens were identified up to species level. Descriptions, illustrations and key to genera and species of Scymnini and Stethorini of southern India were prepared. The study encompasses 28 species of Scymnini of which six are putative new species. Two species are recorded for the first time in India and two species each from south India and Kerala are new records. Scymnini include Axinoscymnus, The genera treated under Cryptolaemus, Horniolus, Nephus, Sasajiscymnus and Scymnus. The genus Scymnus, represented by 20 species, of which 18 species are placed in three subgenera viz., Scymnus, Neopullus and Pullus. Two species are treated separately, as these differ distinctly from the known subgenera. The genus Nephus is represented by three species, Axinoscymnus with two species and Cryptolaemus, Horniolus and Sasajiscymnus with one species each. Stethorini are represented by 10 species in two genera: Stethorus and Parastethorus. Two putative new species of the tribe are described. Six species of Stethorini are new reports for Kerala. Two subgenera recognized under the genus Stethorus are Stethorus and Allostethorus. represented by four species each. Stethorus keralicus, one of the most common species, has been treated separately in this study, as its characters are not in agreement with the known subgenera. The genus Parastethorus is represented by only one species. The prey ranges of Scymnini and Stethorini were documented. Species distribution map were prepared for the species studied. Twenty one species of prey in four families viz., Aphididae, Pseudococcidae, Aleyrodidae and Diaspididae were recorded in association with the tribe Scymnini. Two new prey records for Scymnini are Toxoptera odinae for Scymnus pyrocheilus and Saccharicoccus sacchari for Nephus tagiapatus. Among Scymnini, Scymnus coccivora and S. saciformis are widely distributed with wider host range of six species as prey, while species of Axinoscymnus, though widely distributed, is specific to whiteflies. Among Stethorini, Stethorus pauperculus was found to be the predominant species with wider host range, while Stethorus keralicus was specific to Raoiella indica. New prey records for Stethorini includes Tetranychus okinawanus and T. truncatus for Stethorus forficatus; T. macfarlanei for S. pauperculus and Eutetranychus orientalis for Parastethorus indira. For barcoding the species of Stethorini, DNA was isolated using Qiagen DNeasy blood and tissue kit and the COI locus was amplified and sequenced. The sequences were aligned and characteristic barcode gaps were identified for Parastethorus indira, Stethorus forficatus, S. pauperculus, S. rani, S. keralicus, S. (Allostethorus) sp. 1 and S. (Stethorus) sp.1. Pairwise distances between the sequences were analysed which showed that intraspecific divergence ranged between 0.00 to 0.03, while the interspecific distance ranged between 0.14 to 0.24. A phylogenetic tree was constructed with 21 sequences in MEGA 7 using the maximum likelihood tree method. The sequences were submitted to GenBank (NCBI) and to BOLD for the generation of species specific barcodes. The study identified 38 species of predatory coccinellids in the tribe Scymnini and Stethorini in association with aphids, mealybugs, whiteflies, scales and mites, which are serious pests of crops. Knowledge on the taxonomy of these predators and their prey range throws light on the potential of the above groups in biocontrol of sucking pests.
Taxonomy of the tribe coccinellini (Coleoptera: Coccinellidae) of Kerala
(Department of Agricultural Entomology, College of Agriculture, Padannakkad, 2024-04-09) Vishnu Manoj; Vidya, C V
Coccinellidae is one of the most diverse families in the order Coleoptera constituting 6000 species classified into 360 genera worldwide. Coccinellids have a diverse spectrum of hosts, from specialised predation on fragile-bodied insects to fungal feeders, pollen feeders, and stringent plant feeders. Tribe Coccinellini includes predators and a few mycophagous insects. Their predatory nature is well utilized in the biological control of different crop pests. An examination of the diversity of Coccinellini is critical for their optimal utilization in an integrated pest management approach. Being the biodiversity hotspot, Coccinellini fauna could be diverse in Kerala. However, comprehensive studies on the taxonomy of Coccinellini of Kerala are meager. Hence the present study contributes to the knowledge of predaceous coccinellids of Kerala. The research work “Taxonomy of the tribe Coccinellini (Coleoptera: Coccinellidae) of Kerala” was carried out in the Department of Entomology, College of Agriculture, Padannakkad during 2020-2022 to elucidate the taxonomy of the tribe Coccinellini in different agricultural ecosystems of Kerala and to prepare an illustrated key for the identification of the species of Coccinellini. Purposive surveys were carried out representing the five agroecological zones of Kerala viz., Coastal plain, midland laterites, foothills, high hills and Palakkad plain covering 29 locations in eight districts viz., Kasaragod, Kannur, Wayanad, Malappuram, Thiruvananthapuram. Palakkad, Thrissur, Kottayam and The adult beetles were collected from the host plant by hand picking and sweeping. The collected specimens were subjected to wet preservation by storing in 70 percent ethanol and dry preservation. The specimens were mounted onto the narrow end of a triangular white ivory card with fevicol® and were xxv pinned using ‘3’ size entomological pins. The pinned specimens were labelled with the following details viz., location, date of collection, name of the collector and its associated host plant. These specimens were dried at 50-60ºC in oven for a week and stored for further studies. Specimens available in the Department of Entomology at College of Agriculture, Padannakkad were also utilized for the study. The specimens were first grouped based on the pattern on pronotum and elytra. These were digested and dissected to study the taxonomic characters viz., antenna, labrum, mandible, maxilla, labium, prosternal carina, post coxal line, male genitalia and female genitalia. Descriptions, illustrations and key to species of Coccinellini of Kerala were prepared. Based on the literature collected and taxonomic keys, the identification of the species was done. Species distribution map was prepared with the help of QGIS software. The study explored ten species belonging to eight genera viz., Anegleis Iablokoff-Khnzorian, Cheilomenes Chevrolat, Coccinella Linnaeus, Coelophora, Mulsant, Harmonia Mulsant, Illeis Mulsant, Micraspis Chevrolat and Propylea Mulsant. The species recognized are Anegleis cardoni (Weise), Coccinella septempunctata Linnaeus, C. transversalis Fabricius, Coelophora bissellata Mulsant, C. saucia (Mulsant), Harmonia octomaculata (Fabricius), Illeis cincta (Fabricius), Cheilomenes sexmaculata (Fabricius), Micraspis discolor (Fabricius) and Propylea dissecta (Mulsant). This study illustrated the faunal composition of Coccinellini of Kerala, their host range and geographical distribution. A total of 22 host plants under families Arecaceae, Gramineae, Compositae, Solanaceae, Fabaceae, Musaceae, Pedaliaceae, Cucurbitaceae, Malvaceae, Moraceae and Convolvulaceae from which the specimens were collected. Aphids (Aphis craccivora) and whiteflies were the prey found associated during the study. The information provided can be utilized in efficient integrated pest management of different pests of crops by lady beetles. Coccinellidae is one of the most diverse families in the order Coleoptera constituting 6000 species classified into 360 genera worldwide. Coccinellids have a diverse spectrum of hosts, from specialised predation on fragile-bodied insects to fungal feeders, pollen feeders, and stringent plant feeders. Tribe Coccinellini includes predators and a few mycophagous insects. Their predatory nature is well utilized in the biological control of different crop pests. An examination of the diversity of Coccinellini is critical for their optimal utilization in an integrated pest management approach. Being the biodiversity hotspot, Coccinellini fauna could be diverse in Kerala. However, comprehensive studies on the taxonomy of Coccinellini of Kerala are meager. Hence the present study contributes to the knowledge of predaceous coccinellids of Kerala. The research work “Taxonomy of the tribe Coccinellini (Coleoptera: Coccinellidae) of Kerala” was carried out in the Department of Entomology, College of Agriculture, Padannakkad during 2020-2022 to elucidate the taxonomy of the tribe Coccinellini in different agricultural ecosystems of Kerala and to prepare an illustrated key for the identification of the species of Coccinellini. Purposive surveys were carried out representing the five agroecological zones of Kerala viz., Coastal plain, midland laterites, foothills, high hills and Palakkad plain covering 29 locations in eight districts viz., Kasaragod, Kannur, Wayanad, Malappuram, Palakkad, Thrissur, Kottayam and Thiruvananthapuram. The adult beetles were collected from the host plant by hand picking and sweeping. The collected specimens were subjected to wet preservation by storing in 70 percent ethanol and dry preservation. The specimens were mounted onto the narrow end of a triangular white ivory card with fevicol® and were pinned using ‘3’ size entomological pins. The pinned specimens were labelled with the following details viz., location, date of collection, name of the collector and its associated host plant. These specimens were dried at 50-60ºC in oven for a week and stored for further studies. Specimens available in the Department of Entomology at College of Agriculture, Padannakkad were also utilized for the study. The specimens were first grouped based on the pattern on pronotum and elytra. These were digested and dissected to study the taxonomic characters viz., antenna, labrum, mandible, maxilla, labium, prosternal carina, post coxal line, male genitalia and female genitalia. Descriptions, illustrations and key to species of Coccinellini of Kerala were prepared. Based on the literature collected and taxonomic keys, the identification of the species was done. Species distribution map was prepared with the help of QGIS software. The study explored ten species belonging to eight genera viz., Anegleis Iablokoff-Khnzorian, Cheilomenes Chevrolat, Coccinella Linnaeus, Coelophora, Mulsant, Harmonia Mulsant, Illeis Mulsant, Micraspis Chevrolat and Propylea Mulsant. The species recognized are Anegleis cardoni (Weise), Coccinella septempunctata Linnaeus, C. transversalis Fabricius, Coelophora bissellata Mulsant, C. saucia (Mulsant), Harmonia octomaculata (Fabricius), Illeis cincta (Fabricius), Cheilomenes sexmaculata (Fabricius), Micraspis discolor (Fabricius) and Propylea dissecta (Mulsant). This study illustrated the faunal composition of Coccinellini of Kerala, their host range and geographical distribution. A total of 22 host plants under families Arecaceae, Gramineae, Compositae, Solanaceae, Fabaceae, Musaceae, Pedaliaceae, Cucurbitaceae, Malvaceae, Moraceae and Convolvulaceae from which the specimens were collected. Aphids (Aphis craccivora) and whiteflies were the prey found associated during the study. The information provided can be utilized in efficient integrated pest management of different pests of crops by lady beetles.
Taxonomy of the tribe epilachnini (Coleoptera: Coccinellidae) of Kerala
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2020) Beegam Salma, M P; Vidya, C V