http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/297 2026-04-20T13:52:38Z 2026-04-20T13:52:38Z Ranjini S Francy K Kakkassery Joyce Jose http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/309 2024-02-28T09:08:12Z 2022-12-01T00:00:00Z

Studies on the taxonomy of aquatic heteropteran bugs (order: Hemiptera) from selected habitats of Kerala and their efficacy as biocontrol agents on mosquito larvae of Culex quinquefasciatus say Ranjini S; Francy K Kakkassery; Joyce Jose Kerala represented a wide variety of flora and fauna and many aquatic ecosystems. Aquatic insects are abundant in most freshwater habitats and often exhibit high diversity. Among them, Suborder Heteroptera has a diverse group of bug species, and they are adapted to various habitats like terrestrial, fully aquatic, and semi-aquatic. Aquatic and semi-aquatic bugs are also called as “water bugs”. They perform several critical roles in ecosystem functioning by virtue of their numerical abundance, taxonomic diversity, and trophic levels. This research study is mainly concentrated on the taxonomy of aquatic heteropteran bugs from selected habitats of Kerala and the biocontrol experimental study of selected predators of water bugs on the larvae of Culex mosquitoes. The investigation was carried out from the year 2016 to 2020. The water bugs were collected from a total of 109 locations of 14 Districts in Kerala and 12 different aquatic habitats were selected for this research study. Minimum number of samples were collected by using simple random sample method. Then they were sorted and transferred to air tightened bottles containing 70% alcohol. All the collected samples were identified at species level with the help of taxonomic keys, monographs, and published literatures. A total of 65 species belongs to 34 genera and 14 families of 3 infraorders were recorded during the study. Each species was taxonomically described, and the locations were mentioned. Among these, 30 species were new records from Kerala. In which, 13 species were reported for the first time from South India. The distribution map of 30 new recorded species from Kerala was generated with the help of ‘QGIS’ software. Identification key of all the explored infraorders, families, genera, and species of the water bugs were provided. The biological control experimental study of selected species of predatory water bugs such as Laccotrephes ruber Linnaeus, 1764, Ranatra filiformis Fabricius, 1790, and Diplonychus rusticus Fabricius, 1781 on the species of disease-causing filarial vector, Culex quinquefasciatus Say, 1823. The above said predators were very commonly found and they were collected from the selected aquatic habitats of Palakkad District for this study. The mosquito larvae were sufficiently reared by using the water mixed with decayed vegetable leaves in a plastic bucket and kept for one week in the household areas and the preys were collected from this. Both predators and preys were identified with the help of standard taxonomic keys and published literatures. The experimental data was statistically analysed with the help of the computer software “SPSS 22” and the efficacy of three selected water bugs were assessed. The predatory efficiency was found more by the predator L. ruber Linnaeus, followed by D. rusticus Fabricius, and R. filiformis Fabricius. The present research study was proved and confirmed that the water bugs were the predacious carnivores and biocontrol agents of mosquito larvae, C. quinquefasciatus Say.

2022-12-01T00:00:00Z Nitha Bose C Francy K Kakkassery Binoy CF http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/308 2024-03-13T05:24:37Z 2023-04-01T00:00:00Z

Studies on molecular characterisation and phylogenetic analysis of dragonflies and damselflies (Odonata: Insecta) of selected habitats of Kerala Nitha Bose C; Francy K Kakkassery; Binoy CF Odonata is a primitive order of class Insecta. The order is divided into three suborders- Anisoptera, Zygoptera and Anisozygoptera. Anisoptera is the suborder of dragonflies and damselflies belonging to the suborder Zygoptera. Anisozygoptera is a living fossil and has only 3 species representatives globally. Odonates are hemimetabolous insects and both larval and adult forms are predators. They are amphibiotic; egg and larval development take place in water and adults are aerial. Odonates are naturally considered as biocontrol agents and bioindicators. Various habitats of high land, midland and low land regions of 5 districts of Kerala were selected for the study. A total of 73 locations were observed in the Thrissur, Ernakulam, Palakkad, Wayanad and Idukki districts of Kerala. The observed habitats include streams, rivers, ponds, lakes, paddy fields, ditches and estuaries. A total of 71 species (33 species of damselflies and 38 species of dragonflies) were observed during the study. They belong to 10 families and 43 genera. The Western Ghats endemic species recorded during the work were Aciagrion approximans krishna, Agriocnemis keralensis, Pseudagrion indicum and Protosticta gravelyi. The rarely found species Paracercion malayanum is the first record from central and northern Kerala. Taxonomic keys for the observed 71 species of odonates were prepared. Traditionally organisms were classified based on morphological features. Many research workers pointed out the limitations of traditional taxonomy. These challenges can be overcome by molecular taxonomic approaches. The results of phylogenetic analysis become more convincing when multiple marker genes are included in the study. So, the present work focused on mitochondrial COI gene and nuclear 18S rRNA gene for the molecular characterisation and phylogenetic assessment of selected odonates of Kerala. Molecular characterisation of 34 species belonging to 28 genera was done. Partial COI gene, 18S rRNA gene sequences and translated protein sequences were generated. Of these, twelve COI gene sequences and twenty three 18S rRNA gene sequences are the first worldwide GenBank records. Mitochondrial COI sequences can be used for precise and faster identification of odonate species and phylogenetic studies. Nuclear 18S rRNA gene sequences are beneficial in higher level phylogenetic analysis. Phylogenetic analyses of two suborders and selected families, based on partial COI and 18S rRNA gene sequences were carried out and genetic divergence values among odonates were estimated. The efficiency of partial COI and 18S rRNA marker genes in resolving relationships was studied. A detailed comparison of trees based on both marker genes revealed the efficiency of COI over the 18S rRNA gene in resolving family and suborder trees. Phylogenetic analyses of the 27 genera were done based on COI gene sequences. The results of the analyses and the calculated genetic divergence values provided insights into intraspecific and interspecific genetic variation of odonates across large geographic distances. The majority of odonates selected for the study showed low genetic variability over long distances (different countries and continents) except for eight species. When comparing the results, genetic variability was lesser in damselflies and considerably high in dragonflies. The estimated interspecific divergence values within each genus showed that maximum and minimum interspecific divergence values were possessed by genus Tholymis and genus Dysphaea respectively. Another finding of the study was the close genetic similarity observed between morphologically dissimilar and geographically distant species.

2023-04-01T00:00:00Z Anila K Francy K Kakkassery http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/299 2024-02-24T05:46:28Z 2022-01-01T00:00:00Z

Studies on the ecology and behaviour patterns of antlion larvae (family: Myrmeleontidae, order: Neuroptera) of selected habitats of Kerala Anila K; Francy K Kakkassery

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