Vapor-phase toxicity of Derris scandens Benth.-derived constituents against four stored-product pests

The vapor-phase toxicity of Derris scandens Benth.-derived constituents was evaluated against four stored-product pests ( Callosobruchus chinensis L., Sitophilus oryzae L., Rhyzopertha dominica L., and Tribolium castaneum H.) using fumigation bioassays and compared to those of commonly used insecticides. The structures of all constituents of were characterized by spectroscopic analyses [nuclear magnetic resonance (NMR) and mass spectrometry]. The sensitivity of the test insect to compounds varied with exposure time, concentration, and insect species. Over 100% mortality after 24 h was achieved with the compounds osajin (2), scandinone (5), sphaerobioside (8), and genistein (9) against all of the test insects, while laxifolin (3) and lupalbigenin (4) showed 100% mortality after 72 h against T. csataneum and R. dominica . Scandenone (1), scandenin A (6), and scandenin (7) were less effective. Among the insects, C. chinensis , S. oryzae , and R. dominica were more susceptible to the treatments, whereas T. castaneum was less susceptible. The results of fumigation tests indicated that compounds from D. scandens whole plant extract are potential candidates to control stored-product pests.     

Reproductive phenology of Calophyllum inophyllum in Yeppoon, Australia and Meegoda Western Province, Sri Lanka

Reproductive phenology of multiple use native plant Calo- phyllum inophyllum L. was studied in Yeppoon (23°7’60″ S, 150°43’60″ E), northern Australia (southern hemisphere) and in Meegoda (6o18′51″N, 80o31′3″E), Sri Lanka (northern hemisphere). C. inophyllum trees in Yeppoon, Australia had relatively shorter flowering periods, shorter floral life spans, longer fruit life spans, smaller flowers and larger fruits compared to those in Meegoda, Sri Lanka. Although the number of flower buds/ inflorescence was comparatively higher in Meegoda, C. inophyllum trees in both locations had similar mean number of mature fruits/ cluster due to the higher floral abscission in C. inophyllum trees at Meegoda. Despite having a comparatively lower fruit yield (664 000 fruts·ha 1·a 1), C. inophyllum trees in Yeppoon had higher kernel weights (2 988.0±853.2 kg·ha -1 ·a -1 ) and oil yields (1 332.6±380.5 kg·ha - 1 ·a -1 ) compared to those in Meegoda.     

Ethanolic extract of Azadirachta indica (A. Juss.) causing apoptosis by ROS upregulation in Dirofilaria immitis microfilaria

Dirofilaria immitis is the causative agent of cardiopulmonary dirofilariasis in the Canine family. The aim of the study was to evaluate the efficacy of the ethanolic extract of Azadirachta indica leaves (EEA) against the microfilaria (mf) of D. immitis in vitro. EEA was evaluated for different compound classes through HPTLC. Relative motility, mortality and morphological alterations were observed in the mf after exposure to EEA. The effect of EEA on redox status in the treated mf was evaluated by some key enzymatic and non-enzymatic parameters. An enhanced reactive oxygen species (ROS) level in the treated mf along with altered redox status was evident. DNA fragmentation and terminal-deoxynucleotidyl-transferase dUTP nick end labeling (TUNEL) confirmed apoptosis. In addition, western blotting revealed down-regulation of anti-apoptotic protein and up-regulation of pro-apoptotic proteins. Taken together, the microfilaricidal activity of EEA can be attributed to its capacity to inflict oxidative stress culminating in apoptosis.     

Novel role of photoinsensitive alleles in adaptation of soybean [Glycine max (L.) Merr.] to rainfed short growing seasons of lower latitudes

Soybean is a temperate photosensitive crop but has adapted to sub-tropical and tropical countries of lower latitudes also. Photoperiodic and maturity genes confer latitudinal adaptation in this crop. Genotyping of accessions of higher latitudes have shown the role of photoinsensitivity, conferred by recessive photoperiodic alleles (e1/e2/e3/e4), in adaptation of the crop to high latitudes but information is not available for lower latitudinal countries like India. We genotyped and calculated the photosensitivity of 101 cultivated Indian soybean varieties and found that majority of the varieties (86) were photosensitive and had the dominant alleles at these loci. Four genotypic classes (e1-as/E2/E3/E4, E1/e2/e3/E4, E1/e2/E3/E4 and E1/E2/e3/E4) were observed for varieties with recessive alleles. Photoinsensitive alleles at E1 and E2 loci significantly reduced the days to flower, maturity and photosensitivity percentage. Adaptive role of photoperiodic alleles was inferred from breeder seed requirement of these varieties for 35 years. Although the photosensitive class contributed 81% to the total seed requirement the weighted mean contribution of this class (380 Q/year) was far less than that of photoinsensitive class (648 Q/year). Photoinsensitivity is essential for perpetuation of crop in higher latitudes. Present report highlights the novel role of photoinsensitive alleles in adaptation of soybean to rainfed, short growing and sub-tropical conditions of lower latitudes by conferring earliness.

     

Brown Stink Bug (Hemiptera: Pentatomidae) Damage to Seedling Corn and Impact on Grain Yield

Brown stink bugs, Euschistus servus, are an important early-season pest of field corn in the southeastern United States. Feeding in the early stages of corn development can lead to a number of growth deformities and deficiencies and, ultimately, a reduction in yield. An observational and two experimentally manipulated trials were conducted in 2017 and 2018 to 1) determine optimal timing for assessing brown stink bug damage, 2) assess the level of damage from which yield compensation can occur, and 3) examine the relationship between brown stink bug density and early-season damage and yield. Fields were identified with infestations of brown stink bugs and a damage rating system for early stages of corn was established. Varying rates of brown stink bug densities were introduced using field cages and damage was assessed throughout the season. The density and duration of stink bug infestations were critical factors for damage potential, with each day of active feeding per plant resulting in a loss of ~14 kg/ha in yield. The level of damage in early stages of corn was categorized into easily identifiable groups, with only the most severe damage leading to a reduction in yield. Moderate and minimal feeding damage did not result in yield loss. This study emphasizes the need for early and frequent scouting of corn to determine the risk of damage and yield loss from brown stink bugs. Results from this study can be used to help develop management programs for brown stink bugs in the early vegetative stages of field corn.     

Antigen-specific lymphocyte proliferation and interleukin production in chickens immunized with killed Salmonella enteritidis vaccine or experimental subunit vaccines

Lymphocyte proliferation and interleukin (IL)-2 and IL-6 levels in serum were measured as indicators of cell-mediated immunity after immunization of chickens with a commercial killed Salmonella enteritidis (SE) vaccine or experimental subunit vaccines of crude protein (CP) extract or the outer membrane protein (OMP). Significantly increased proliferative responses to SE flagella, but not lipopolysaccharide, porin, CP, or OMP, were observed at 1 wk postimmunizarion in the three vaccination groups. The responses to flagella were specific because flagella-induced proliferation was not seen in chickens immunized with adjuvant alone. Of the three immunization protocols, use of the killed SE vaccine appeared most effective because it induced higher flagella-stimulated lymphocyte proliferation at 1 and 2 wk postvaccination compared with the CP- and OMP-vaccinated groups. Significantly increased IL-2 and IL-6 levels in serum were seen at 1 wk postimmunization in the three vaccination groups compared with adjuvant alone, but there were no differences between the killed vaccine and the subunit vaccines at this time, and the levels of both lymphokines returned to baseline at 2 wk postimmunization. We conclude that cell-mediated immunity to SE after vaccination with the killed bacterial vaccine or subunit vaccines is transient and mainly limited to flagella.     

Chirality index, molecular overlay and biological activity of diastereoisomeric mosquito repellents

Both 1-methylisopropyl 2-(2-hydroxyethyl)piperidine-1-carboxylate, (Picaridin((R))) and cyclohex-3-enyl 2-methylpiperidin-1-yl ketone (AI3-37220; 220) have two asymmetric centers, and the four diastereoisomers of each compound are known to have differing degrees of mosquito-repellent activity according to quantitative behavioral assays conducted at the United States Department of Agriculture. Computational chemistry was used to identify the structural and configurational basis for repellent activity. Molecular overlay of the optimized geometries of the lowest energy conformers of the diastereoisomers was investigated to elucidate the role of chiral centers in 220 and Picaridin. It was found that the presence of a chiral carbon alpha to the nitrogen with the S configuration in the piperidine ring is essential to the three-dimensional arrangement of the atoms of the pharmacophore for effective repellent activity.     

Differential responses of macrophages to Salmonella enterica serovars Enteritidis and Typhimurium

Macrophages are major effectors against Salmonella infection, and also transport bacteria between host tissues and provide a protected site for intracellular bacterial replication. We hypothesized that differences in chicken macrophage responses to Salmonella enterica serovar Enteritidis (SE) and serovar Typhimurium (ST) played a role in preferential infection of eggs by SE compared with ST. To test this hypothesis, we determined bacterial phagocytosis and intracellular viability and macrophage nitric oxide (NO) production following in vitro infection with SE or ST in the presence or absence of interferon-gamma (IFN-gamma). The effects of bacterial components, lipopolysaccharide (LPS), outer membrane proteins (OMP) and flagella, on NO production were also assessed. Our results showed: (1) in the presence or absence of IFN-gamma, the percentage macrophages phagocytizing SE and ST was similar; (2) the number of intracellular viable SE was significantly reduced compared with ST in the presence or absence of IFN-gamma; (3) increased macrophage necrosis was seen in the presence of IFN-gamma and ST; (4) Salmonella infection acted synergistically with IFN-gamma in induction of nitric oxide production; and (5) in the absence of IFN-gamma, macrophages produced significantly greater NO following treatment with SE outer membrane protein or flagella compared with ST OMP or flagella, while in the presence of IFN-gamma significantly less NO was produced following treatment with SE-LPS compared with ST-LPS. These results suggest that differential responses of chicken macrophages to SE versus ST may result in increased macrophage death with ST, which could result in an increased inflammatory response as compared to SE.     

Regulation of Leaf Senescence and Yield in Mungbean (Vigna radiata L. Wilczek)

Foliar application of benzyladenine at preanthesis stage retarded leaf senescence in mungbean. Chemical spray increased leaf chlorophyll, soluble protein, specific leaf weight, net photosynthetic rate and nitrate reductase activity. Number of pods, grain yield, harvest index and 100-seed weight were significantly improved by benzyladenine treatment. The possibility of higher pod-filling and thus, yield by chemical regulation of leaf senescence is evident in mungbean.