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Objective Insecticidal activity of Clerodendrum capitatum extracts against the stored product insect pest, Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst) were investigated. Materials and Methods Hundred grams of C. capitatum powder was sequentially extracted with a series of solvents of increasing polarity in a Soxhlet apparatus and the extracts were concentrated on rotary evaporator to make it solvent free and the residue dissolved in a known volume of methanol and the solution was assayed for insecticidal activity by the fumigant toxicity. Hexane extract which showed maximum activity was selected for the preparation of herbal formulation and for its insecticidal properties and phytotoxicity. The herbal formulation obtained from leaves of C. capitatum was investigated by GCMS and GC/FID. Results Clerodendrum capitatum ethyl extract had a very strong repellent activity to adults of all three major stored grain insects and was significantly repellent at a 1.58 mg/cm2. The hexane extract (oil) had high fumigant activity with LC50 values in the range between 25 and 32 µg/L. A total of 14 components representing 97.8% of the formulation were identified and the main compounds in the formulation were found to be 2-Heptanone, 3-methyl (33.9 %) and Hexahydrofarnesyl acetone (25.3%) followed by 3-Dodecen-1-al (10.2%) and 8-Methyl-1-undecene (4.9%). Further, herbal formulation was found to be highly toxic to mixed age cultures of all three major stored grain insect pests which recorded 80%–90% mortality at dose of 200 µg/L in 24 h exposure, where as 100% mortality achieved at dose of 200 µg/L in 72 h exposure, respectively. Conclusion The results indicate that extracts and formulation of C. capitatum has the potential to be developed in to a natural insecticide or repellent for controlling of stored product beetles.

Recent studies proved that the biofumigants could be an alternative to chemical fumigants against stored grain insect pests. For this reason, it is necessary to understand the mode of action of biofumigants. In the present study the prospectus of utilisingLantana camaraas a potent fumigant insecticide is being discussed. Inhibition of acetylcholinesterase (AChE) by Coumaran, an active ingredient extracted from the plantL. camara, was studied. The biofumigant was used as an enzyme inhibitor and acetylthiocholine iodide as a substrate along with Ellman’s reagent to carry out the reactions. Thein vivoinhibition was observed in both dose dependent and time dependent in case of housefly, and the nervous tissue (ganglion) and the whole insect homogenate of stored grain insect exposed to Coumaran. The possible mode of action of Coumaran as anacetylcholinesteraseinhibitor is discussed.

Nature Communications 11(1), 1314 (1-11) (2020). doi:10.1038/s41467-020-14862-4, Major Histocompatibility Complex (MHC) class I molecules selectively bind peptides for presentation to cytotoxic T cells. The peptide-free state of these molecules is not well understood. Here, we characterize a disulfide-stabilized version of the human class I molecule HLA-A*02:01 that is stable in the absence of peptide and can readily exchange cognate peptides. We present X-ray crystal structures of the peptide-free state of HLA-A*02:01, together with structures that have dipeptides bound in the A and F pockets. These structural snapshots reveal that the amino acid side chains lining the binding pockets switch in a coordinated fashion between a peptide-free unlocked state and a peptide-bound locked state. Molecular dynamics simulations suggest that the opening and closing of the F pocket affects peptide ligand conformations in adjacent binding pockets. We propose that peptide binding is co-determined by synergy between the binding pockets of the MHC molecule., Published by Nature Publishing Group UK, [London]