LARVICIDAL AND ENZYME INHIBITORY EFFECTS OF ACALYPHA FRUTICOSA (F.) AND CATHARANTHUS ROSEUS L (G) DON. LEAF EXTRACTS AGAINST CULEX QUINQUEFASCIATUS (SAY.) (DIPTERA: CULICIDAE)

ABSTRACTObjective: The prime objective of this study is to evaluate the larvicidal and enzyme inhibitory effects of Acalypha fruticosa and Catharanthus roseusleaf extracts against Culex quinquefasciatus.Methods: Insecticidal susceptibility tests were carried out using the World Health Organization standard method, and the mortality was observedafter 24 hrs exposure.Results: The tested extracts showed a significant larvicidal activity depending on the dose of the plant extracts. However, maximum larval mortalitywas detected in ethyl acetate extract of A. fruticosa with a lethal concentration (LC50) value of 253.08 ppm and (LC90) value of 455.40 ppm followedby hexane extract of C. roseus with LC50 value of 645.33 ppm and LC90 value of 1452.88 ppm against the larvae of C. quinquefasciatus. In control, therewere five different fractions of α-carboxylesterases resolved in the gel with the mobilities ranging between 0.14 and 0.66. β-carboxylesterase isozymeprofile of larvae treated with hexane extract of A. fruticosa showed higher enzyme activities by way of intense staining of fractions both at 1/4 and1/10 LC50 value of 48 hrs treatments. A. fruticosa ethyl acetate extract, and C. roseus hexane extract exposed larvae indicated increased quantitiesof β-Est4/5 isozymes in the concentration of 1/4 and 1/10 of LC50 value of 24 hrs treatment when compared to control. The protein quantity in themajority of treatments decreased compared to control.Conclusion: The results revealed that the organic leaf extract of A. fruticosa and C. roseus had significant larvicidal and enzyme inhibitory effectsagainst C. quinquefasciatus.Keywords: Acalypha fruticosa, Catharanthus roseus leaves extract, β-carboxylesterase, Culex quinquefasciatus, Lethal concentration50

Genetic relatedness of six South Indian agriculturally important moth species (Lepidoptera: Noctuoidea) based on 28S rRNA-D₂region sequence analysis

364-371Molecular phylogenetic evidence from 28S rRNA-D2 expansion segment was used to facilitate differentiation of six different pest species of moths from the superfamily Noctuoidea. The expansion segment of the large ribosomal subunit of 28S rRNA-D2 region was amplified, sequenced and used to construct a phylogenetic tree on the basis of N-J phylogeny method. The topology on the basis of this phylogenetic tree supported a large monophyly for <i style="mso-bidi-font-style: normal">Helicoverpa armigera Hub. and Spodoptera <i style="mso-bidi-font-style: normal">litura Fab. in one cluster, Euproctis fraterna More, <i style="mso-bidi-font-style: normal">Amsacta albistriga Walker and Pericallia <i style="mso-bidi-font-style: normal">ricini Fab. in another cluster, and <i style="mso-bidi-font-style: normal">Earias vitella Fab. in third cluster. The rRNA sequences were also analyzed for the genetic variation using the predicted secondary structure models for all the six species. This analysis revealed variation in the structure of D2 expansion segments at its various arms. Though the multiple sequence alignment showed one large cluster with three sub-clusters and 96% homology among these pest species, the predicted secondary structure models did not show any such close relationships. These results reflect the functional diversity occurred due to the changes acquired slowly at the rRNA structure to perform their function during evolution rather than the homology in the nucleotide sequences or rRNA morphometry among different species of insects

Detection of antibacterial activity and its characterization from the marine macro-algae <i>Sargassum wightii</i> (Greville ex J. Agardh 1848)

1365-1371Natural occurrence of a compound, mono-ethylhexylphthalate (MEHP) in one of the column fractions of marine macro-algae Sargassum wightii with promising antibacterial activity is examined. Infrared spectroscopy disclosed the presence of one acid group, one ester group, aromatic and aliphatic chains. 1H and 13C NMR spectra along with IR data predicted the structure of MEHP. Abundance of MEHP in the column fraction IV of S. wightii and its effective antibacterial activity points toward the potential utility of macro-algae Sargassum wightii as a source of novel biomedical compound