Ovicidal activity of Atalantia monophylla (L) Correa against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Comprehensive and evolutionary analysis of Spodoptera litura-inducible Cytochrome P450 monooxygenase gene family in Glycine max elucidate their role in defense

Plants being sessile organisms and lacking both circulating phagocytic cells and somatic adaptive immune response, have thrived on various defense mechanisms to fend off insect pests and invasion of pathogens. CYP450s are the versatile enzymes, which thwart plants against insect pests by ubiquitous biosynthesis of phytohormones, antioxidants, and secondary metabolites, utilizing them as feeding deterrents and direct toxins. Therefore, a comprehensive analysis of biotic stress-responsive CYPs from Glycine max was performed to ascertain their function against S. litura-infestation. Phylogenetic analysis and evolutionary studies on conserved domains and motifs disclosed the evolutionary correspondence of these GmCYPs with already characterized members of the CYP450 superfamily and close relatedness to Medicago truncatula. These GmCYPs were mapped on 13 chromosomes; they possess 1-8 exons; they have evolved due to duplication and are localized in endoplasmic reticulumn. Further, identification of methyl-jasmonate, salicylic acid, defense responsive and flavonoid biosynthesis regulating cis-acting elements, their interaction with biotic stress regulating proteins and their differential expression in diverse types of tissues, and during herbivory, depicted their responsiveness to biotic stress. Three-dimensional homology modelling of GmCYPs, docking with heme cofactor required for their catalytic activity and enzyme-substrate interactions were performed to understand the functional mechanism of their action. Moreover, to gain insight into their involvement in plant defense, gene expression analysis was evaluated, which revealed differential expression of 11 GmCYPs upon S. litura-infestation, 12 GmCYPs on wounding while foliar spray of ethylene, methyl-jasmonate and salicylic acid differentially regulated 11 GmCYPs, 6 GmCYPs, and 10 GmCYPs respectively. Our study comprehensively analysed the underlying mechanism of GmCYPs function during S. litura-infestation, which can be further utilized for functional characterization to develop new strategies for enhancing soybean resistance to insect pests.

Developmental response of Spodoptera litura Fab in response to plant extract of Desmostachya bipinnata (L.) and its effect on non-target organism, earthworm (Eisenia fetida)

Impact of chloroform extract of Desmostachya bipinnata was evaluated on armyworm Spodoptera litura (Lepidoptera: Noctuidae). The chloroform extract of D. bipinnata was subjected to GC-MS analysis to elucidate the vital 12 compounds. The mortality of S. litura was tested at four different concentrations viz., 0.5, 1.0, 1.5, and 2.0 %, which exhibited a dose-dependent response. Mortality was significant at a concentration of 2%. Accrued LC₅₀ (lethal concentration) value was 0.15%. The developmental duration of larva and pupa was significantly increased in all treatments. Reduction in weight of pupae in treated groups was noticed and was compared with control. Longevity of S. litura decreased in all tested treatments and being most significant at concentrations of 1.5 and 2%. Simultaneous reduction in fecundity of S. litura was observed. Pathological changes were noticed in the mid gut of S. litura at concentrations of 1 and 1.5%. No significant impacts on earthworm were observed. The results of the present study revealed that chloroform extract from D. bipinnata, an old-world perennial grass, shown effective bio-pesticidal activity against S. litura, an important agricultural pest.

Lagenaria siceraria - synthesised ZnO NPs - a valuable green route to control the malaria vector Anopheles stephensi

Malaria is a dangerous disease affecting humans and animals in tropical and subtropical areas worldwide. According to recent estimates, 3.2 billion people are at risk of malaria. Many drugs are in practices to control this disease and their vectors. Eco-friendly control tools are needed to fight vectors of this important disease. Nanotechnology is playing a key role in the fight against many public health emergencies. In the present study, Lagenaria siceraria aqueous peel extract was used to prepare zinc oxide nanoparticles (ZnO NPs), then tested on Anopheles stephensi eggs, larvae and pupae. The L. siceraria-synthesised ZnO NPs were characterized additionally by FTIR, AFM, XRD, UV-Vis spectroscopy, EDX, and SEM spectroscopy The ovicidal, larvicidal, pupicidal and repellent activities of L. siceraria and green-synthesised ZnO NPs were analysed on A. stephensi. The potential mechanism of action of ZnO NPs was studied investigating the changes in various enzyme activities in A. stephensi IV instar larvae. Furthermore, the smoke toxicity of L. siceraria-based cones against A. stephensi evoked higher mortality if compared with the control. Overall, the present study concluded that L. siceraria peel extract and its mediated green synthesised ZnO NPs represent a valuable green option to manage against malaria vectors.

Biological Evaluation of Endothall, a Dicarboxylic Acid Analog of Norcantharidin, and Cantharidin on Oriental Leafworm, Spodoptera litura (Lepidoptera: Noctuidae)

Cantharidin is a highly potent toxin produced by insects belonging to the order Coleoptera and family Meloidae. The insecticidal activity of cantharidin against different orders of insects has been well documented. Although it is highly effective, its extraction and synthesis is very tedious. Consequently, much work is underway to synthesize the bioactive analogs of norcantharidin and study their relative structures. In this study, we investigate the acute and chronic toxicological effects of cantharidin and endothall, an analog of norcantharidin, using an age-stage-based two-sex life table methodology. Results reveal the acute toxicity of these compounds to Spodoptera litura Fabricius (Lepidoptera: Noctuidae), with the LC50 of cantharidin being 2.10 and endothall being 3.72 ppm, after 72 h posttreatment. Although both the compounds negatively affected the intrinsic rate of population increase (r), finite rate of increase (λ), net reproduction rate (R0), mean generation time (T), doubling time (DT), relative fitness (Rf), biotic potential, and longevity, cantharidin was slightly more effective. Among the reproductive parameters, fecundity was severely affected by cantharidin, which reduced offspring to 42 compared to 528 per female in the control cohort. Both cantharidin and endothall caused similar physiological changes such as weight reduction, wing malformation, and pupal deformities. These findings demonstrate that both cantharidin and endothall are highly toxic to S. litura, particularly in their chronic effects on population parameters. This will help us to understand the biological and ecological interactions in agricultural cropping systems and how their application will modify insect herbivory.

Toxic effect of Atalantia monophylla essential oil on Callosobruchus maculatus and Sitophilus oryzae

The hydrodistillated essential oil of Atalantia monophylla was subjected to GC-MS. Forty compounds were presented in the essential oil. Eugenol (19.76 %), sabinene (19.57 %), 1,2-dimethoxy-4-(2-methoxyethenyl) benzene (9.84 %), beta-asarone (7.02 %) and methyl eugenol (5.52 %) were found the predominant compounds. The oil was tested for fumigant toxicity and repellent activity against Callosobruchus maculatus and Sitophilus oryzae. The development stage of C. maculatus fecundity, adult emergence and also ovicidal activities were studied by the treatment of A. monophylla oil. The oil exhibited considerable fumigation toxicity (70.22 %), repellent activity (85.24 %) and ovicidal activity (100 %) against C. maculatus. The oil significantly reduced the protein, esterase, acetylcholinesterase and glutathione S-transferase on C. maculatus and S. oryzae. It can be considered that A. monophylla has a potential insecticide against stored product pests.

Chemical composition analysis, antioxidant and antibacterial activity evaluation of essential oil of Atalantia monophylla Correa

Background:

Atalantia monophylla Correa. a small tree belongs to the family Rutaceae. It is distributed throughout India and in Tamil Nadu the species is commonly seen in foothills of dry vegetation.

Objective:

The aim was to hydrodistillate and analyze the chemical composition of essential oil from the fresh leaves of A. monophylla Correa. collected in two different seasons (December, 2013 and May, 2014) and to evaluate antioxidant and antibacterial activities of isolated essential oil.

Materials and Methods:

Chemical composition of isolated essential oil was analyzed by gas chromatography, gas chromatography coupled with mass spectrometry. Antioxidant activity of oil was assessed using five different antioxidant test systems. Antibacterial activity of oil was tested against six pathogenic bacteria by broth dilution method.

Results:

Essential oil obtained from the leaves collected during May, 2014 had shown more compounds. Antioxidant activity of oil was moderate when compared with positive control. Minimum inhibitory concentration value of oil was ranges between 139.32 ± 0.001 and 541.11 ± 0.003 µg/mL against all the tested bacteria.

Conclusion:

Result clearly indicates essential oil collected during May, 2014 showed more bioactive compounds.