Comparative efficacy of NeemAzal and local botanicals derived from <Emphasis Type="Italic">Azadirachta indica</Emphasis> and <Emphasis Type="Italic">Plectranthus glandulosus</Emphasis> against <Emphasis Type="Italic">Sitophilus zeamais</Emphasis> on maize

The efficacy of NeemAzal powder, two local neem (Azadirachta indica ) products [neem seed powder (NSP) and neem seed oil (NSO)], as well as a local Lamiaceae, Plectranthus glandulosus leaf powder, applied at four different rates for the control of Sitophilus zeamais was determined. Mortality was recorded 1, 3, 7 and 14 days after S. zeamais infestation, followed by the determination of F₁ progeny production. Grain damage, population increase and grain germination were assessed for treated grains that were stored for 4 months. Grains treated with P. glandulosus powder and NSP had relatively low mortality (5.0–22.5%) after 3 days whereas NeemAzal and NSO had higher mortality (55.0–98.8%). Maximum mortality of 99, 100, 96 and 74% were achieved for NeemAzal (12 g/kg after 14 days), NSO (4 ml/kg after 7 days), NSP (40 g/kg after 14 days) and P. glandulosus powder (40 g/kg, after 14 days), respectively. In the same order, 7-day LC₅₀ values were 0.02 g/kg, 1.46 ml/kg, 12.44 g/kg and 28.9 g/kg. The three neem products greatly reduced progeny emergence, while P. glandulosus powder was less effective. NeemAzal protected the grains against S. zeamais damage better than the local neem products, which in turn provided far better grain protection against the weevil damage than P. glandulosus powder. NeemAzal was superior to the local neem products in grain protection against germination loss, with P. glandulosus being the least effective. NeemAzal and NSO had sufficient efficacy to be a component of an integrated management package for S. zeamais.     

Insecticidal effects of the powdery formulation based on clay and essential oil from the leaves of <Emphasis Type="Italic">Clausena anisata</Emphasis> (Willd.) J. D. Hook ex. Benth. (Rutaceae) against <Emphasis Type="Italic">Acanthoscelides obtectus</Emphasis> (Say) (Coleoptera: Bruchidae)

The bioefficacies of essential oil and aromatized clay powder based on the mixture of clay and essential oil extracted from Clausena anisata were evaluated for their insecticidal activities and their effects on progeny production of Acanthoscelides obtectus. Contact toxicity assayed by coating on bean grains showed that these chemicals caused significant mortality of the test insect. Beetle mortality was dose dependant and after 2-day exposure the aromatized clay powder was more toxic (LD₅₀ = 0.069 μl/g grain) than the pure essential oil (LD₅₀ = 0.081 μl/g grain). There was, however, a highly significant loss of toxicity after 24 and 36 h following treatment with essential oil and aromatized powder, respectively. Both aromatized clay powder and pure essential oil considerably reduced the F₁ progeny insect production. The essential oil evoked moderated repellent action and high fumigant toxicity (LC₅₀ = 0.093 μl/cm³) against adults of A. obtectus. These results suggest that the clay powder could be used to stabilize the essential oil to increase its efficacy for use as an alternative to synthetic insecticides.     

Potential of zimtaldehyde, 4-allyl-anisol, linalool, terpineol and other phytochemicals for the control of the confused flour beetle (Tribolium confusum J. d. V.) (Col., Tenebrionidae)

Toxicity and repellency effects of several pure compounds (of plant origin) against the confused flour beetle (Tribolium confusum) were investigated in a filter paper test. The compounds were α-pinen, β-pinen, 4-allyl-anisol, camphor, 1,8-cineol, eugenol, linalool, menthol, piperin, terpineol, thymol and zimtaldehyde. Five compounds (4-allyl-anisol, linalood, terpineol, thymol and zimtaldehyde) caused enough mortality of this insect to allow the determination of LD₅₀ and LD₉₅ values. Zimtaldehyde and 4-allyl-anisol showed the strongest toxicity effects with LD₅₀ values of 0.04–0.05 μl/cm² within an exposure period of 24 h. When the isolated fumigant effects were tested by separating the insects from the filter paper, the toxicity of zimtaldehyde (LD₅₀=0.29 μl/cm²) was much lower than that of 4-allyl-anisol (LD₅₀=0.10μl/cm²).     

Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the β-adrenergic-like octopamine receptor

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.

     

A glucosylceramide with antimicrobial activity from the edible mushroom <Emphasis Type="Italic">Pleurotus citrinopileatus</Emphasis>

The golden oyster mushroom Pleurotus citrinopileatus is a popular edible mushroom with multifunctional biological activities, but there are a limited number of previous studies on its chemical composition. This is the first report of the isolation of glucosylceramide with antimicrobial activity from the fruiting body of this mushroom. This compound was identified as 1-O-β-d-glucopyranosyl-(2S,3R,4E,8E)-2-[(2R)-2-hydroxyhexadecanoylamino]-9-methyl-4,8-octadecadiene-1,3-diol. The IC₅₀ value of this compound for the growth of Escherichia coli and Staphylococcus aureus was 275.1 μM (200 μg/ml) and 323.2 μM (235 μg/ml), respectively.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.     

Assessing the potential for biological control of potato field pests in Ardabil,Iran: functional responses of <Emphasis Type="Italic">Orius niger</Emphasis> (Wolf.) and <Emphasis Type="Italic">O. minutus</Emphasis> (L.) (Hemiptera: Anthocoridae)

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), and the onion thrips, Thrips tabaci Lind. (Thysanoptera: Thripidae), are significant field pests of potato in the Ardabil region of Iran. Orius niger (Wolf.) and O. minutus (L.) (Hemiptera: Anthocoridae) are locally the predominant natural enemies of these pests. This study compared the functional responses of O. niger and O. minutus to female mites and second instar thrips larvae across a range of prey densities (5, 10, 20, and 40 prey/arena) under controlled conditions of 24 ± 1°C, 50 ± 5% RH and 16:8 h (L:D). The resulting data were appropriately fit to Type II functional response models in four predator–prey interactions, including: (1) O. niger to second instar thrips larvae (a = 0.009 h⁻¹; and T _h = 1.62 h); (2) O. niger to females mites (a = 0.006 h⁻¹ and T _h = 1.28 h); (3) O. minutus to second instar thrips larvae (a = 0.008 h⁻¹ and T _h = 1.93 h) and (4) O. minutus to females mites (a = 0.01 h⁻¹ and T _h = 1.1 h). The number of second instar thrips larvae attacked by O. niger was greater than that by O. minutus (P ≤ 0.01); conversely, the number of females mites attacked by O. minutus was greater than that by O. niger (P ≤ 0.01). These results confirm the potential for both O. niger and O. minutus to make valuable contributions to a biological control program against onion thrips and the two-spotted spider mites infesting potato fields in this region.     

Screening antiacne potency of Indonesian medicinal plants: antibacterial,lipase inhibition,and antioxidant activities

Indonesian medicinal plants were screened as potential sources of antiacne agents. The screening methods were performed using antibacterial assay against Propionibacterium acnes, lipase inhibitor assay, and antioxidant assay. The results showed that from 40 plant materials extracted with methanol and 50% ethanol in water, Caesalpinia sappan was the best extract based on the combined activities: antibacterial (minimum inhibitory concentration 0.13 mg/ml; minimum bactericidal concentration 0.25 mg/ml), lipase inhibitory [50% inhibitory concentration (IC₅₀) 120.0 μg/ml], and antioxidative (IC₅₀ 6.47 μg/ml). Another prospective extract is Intsia palembanica based on its lipase inhibitory activity (IC₅₀ 4.1 μg/ml) and antioxidant activity (IC₅₀ 3.87 μg/ml). Part of this report was presented at the 58th Annual Meeting of the Japan Wood Research Society, Tsukuba, March 2008     

Efficacy of Clausena anisata and Plectranthus glandulosus leaf powder against Prostephanus truncatus (Coleoptera: Bostrichidae) and two strains of Sitophilus zeamais (Coleoptera: Curculionidae) on maize

Powdered leaves of Clausena anisata and Plectranthus glandulosus were evaluated on Cameroonian and German strains of Sitophilus zeamais and Prostephanus truncatus for their insecticidal activities, the effects on progeny production, grain damage and population increase by admixing powders and maize grains. The two powders caused significant mortality of the three insects with P. glandulosus being far more effective than C. anisata. P. truncatus was less susceptible to P. glandulosus powder compared with the two strains of S. zeamais. The German strain (LD₅₀ = 2.75 g/100 g grain) of S. zeamais was less susceptible to P. glandulosus powder than the Cameroonian strain (LD₅₀ = 1.86 g/100 g grain). P. glandulosus unlike C. anisata powder, considerably reduced grain damage, progeny production and population increase. This study shows that there is a great potential for the powder of P. glandulosus as a promising grain protectant for integration within the subsistence farming systems of sub-saharan Africa.     

CT-measured macropores as affected by agroforestry and grass buffers for grazed pasture systems

Agroforestry and grass buffers have been proposed for improving water quality in watersheds. Soil porosity can be significantly influenced by buffer vegetation which affects water transport and water quality. The objective of the study was to compare differences in computed tomography (CT)-measured macroporosity (>1,000-μm diam.) and coarse mesoporosity (200- to 1,000-μm diam.) parameters for agroforestry and grass buffer systems associated with rotationally grazed and continuously grazed pasture systems. Soils at the site were Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf). Six replicate intact soil cores, 76.2 mm diam. by 76.2 mm long, were collected using a core sampler from the four treatments at five soil depths (0–50 cm at 10-cm intervals). Images were acquired using a hospital CT scanner and subsequently soil bulk density and saturated hydraulic conductivity (K _sat) were measured after scanning the cores. Image-J software was used to analyze five equally spaced images from each core. Bulk density was 5.9% higher and saturated hydraulic conductivity (K _sat) values were five times lower for pasture treatments relative to buffer treatments. For the 0–10 cm soil depth, CT-measured soil macroporosity (>1,000 μm diam.) was 13 times higher for the buffer treatments compared to the pasture treatments. Buffer treatments had greater macroporosity (0.020 m³ m⁻³) compared to pasture (0.0045 m³ m⁻³) treatments. CT-measured pore parameters were positively correlated with K _sat. The project illustrates benefits of agroforestry and grass buffers for maintaining soil porosity critical for soil water and nutrient transport.     

Rapid in vitro cloning of a 40-year-old tree of <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss. (Neem) employing nodal stem segments

An efficient in vitro process for rapid clonal propagation of a 40-year-old tree of Azadirachta indica employing nodal stem segments was developed. Season of collection and maturity of explants showed direct influence on bud-break. Nodal stem segments collected during the month of April gave best response. Maximum bud-break (78.6–81%) was obtained when middle order nodes (3rd or 4th node from apex) were taken. Amongst different cytokinins used, 6-benzylaminopurine (BAP) at the concentration of 1.11 μM was found most effective in inducing multiple shoots, whereas inorganic and organic constituents of the medium influenced growth and general condition of proliferating shoots. On an average 3.1 shoots per explant were regenerated in modified Murashige and Skoog medium supplemented with 1.11 μM BAP, 1.43 μM indole-3-acetic acid (IAA) and 81.43 μM adenine hemisulphate. Isolated shoots were rooted in presence of 2.46 μM indole-3-butryic acid (IBA). Root induction took place in 8–10 days with 100% rooting. The in vitro-raised plantlets were successfully transplanted in potted soil and finally grown under field conditions with 100% survival. The genetic fidelity of such in vitro-raised field-grown plants was ascertained by random amplified polymorphic DNA (RAPD) markers. Furthermore, the azadirachtin content of in vitro-cloned plants was found comparable to the mother tree proving their chemical stability also. The protocol developed holds good for in vitro cloning of mature elite neem trees.     

Antioxidative and antiradical activities of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> leaf oils from Thailand

The leaf essential oils (six samples) from three clones of Eucalyptus camaldulensis Dehnh. were characterized by gas chromatography-mass spectrometry. Radical scavenging and antioxidant properties were investigated by the 1,1-diphenyl-2-picylhydrazyl (DPPH) assay and the β-carotene bleaching test. It was found that the whole essential oil and its fractions had significant antioxidant effects when they were tested by each method. In the DPPH assay, the E. camaldulensis leaf oils showed IC₅₀ inhibitory concentrations in the range of 1.75–12.62 mg/ml. In the β-carotene bleaching test, the IC₅₀ valued were in the range of 14.30–118.55 μg/ml. Part of this report was presented at the 18th meeting of the Chugoku-Shikoku Branch of the Japan Wood Research Society, November 2006     

Crop residue effect on crop performance,soil N<Subscript>2</Subscript>O and CO<Subscript>2</Subscript> emissions in alley cropping systems in subtropical China

Land management practices that simultaneously improve soil properties are crucial to high crop production and minimize detrimental impact on the environment. We examined the effects of crop residues on crop performance, the fluxes of soil N₂O and CO₂ under wheat-maize (WM) and/or faba bean-maize (FM) rotations in Amorpha fruticosa (A) and Vetiveria zizanioides (V) intercropping systems on a loamy clay soil, in subtropical China. Crop performance, soil N₂O and CO₂ as well as some potential factors such as soil water content, soil carbon, soil nitrogen, microbial biomass and N mineralization were recorded during 2006 maize crop cultivation. Soil N₂O and CO₂ fluxes are determined using a closed-based chamber. Maize yield was greater after faba bean than after wheat may be due to differences in supply of N from residues. The presence of hedgerow significantly improved maize grain yields. N₂O emissions from soils with maize were considerably greater after faba bean (345 g N₂O–N ha⁻¹) than after wheat (289 g N₂O–N ha⁻¹). However, the cumulated N₂O emissions did not differ significantly between WM and FM. The difference in N₂O emissions between WM and FM was mostly due to the amounts of crop residues. Hedgerow alley cropping tended to emit more N₂O than WM and FM, in particular A. fruticosa intercropping systems. Over the entire 118 days of measurement, the N₂O fluxes represented 534 g N₂O–N ha⁻¹ (AWM) and 512 g N₂O–N ha⁻¹ (AFM) under A. fruticosa species, 403 g N₂O–N ha⁻¹ (VWM) and 423 g N₂O–N ha⁻¹ (VFM) under Vetiver grass. We observed significantly higher CO₂ emission in AFM (5,335 kg CO₂–C ha⁻¹) from June to October, whereas no significant difference was observed among WM (3,480 kg CO₂–C ha⁻¹), FM (3,302 kg CO₂–C ha⁻¹), AWM (3,877 kg CO₂–C ha⁻¹), VWM (3,124 kg CO₂–C ha⁻¹) and VFM (3,309 kg CO₂–C ha⁻¹), indicating the importance of A. fruticosa along with faba bean residue on CO₂ fluxes. As a result, crop residues and land conversion from agricultural to agroforestry can, in turn, influence microbial biomass, N mineralization, soil C and N content, which can further alter the magnitude of crop growth, soil N₂O and CO₂ emissions in the present environmental conditions.     

A model of the biological control of<Emphasis Type="Italic"> Acarus siro</Emphasis> by<Emphasis Type="Italic"> Cheyletus eruditus</Emphasis> (Acari: Acaridae,Cheyletidae) on grain

The aim of the study was to develop a stage-structured within-patch model describing predator-prey interactions of Cheyletus eruditus (Schrank) and Acarus siro L. on stored grain. Parameterisation of the model was done using data from the literature. Due to considerable variance in these data, statistical methods were used to extrapolate the parameters. The results of the simulations were compared with the experimental control of A. siro by C. eruditus on wheat. The results indicated that all life-history studies of A. siro yielded overestimated parameters leading to an unnaturally rapid population growth of A. siro on grain. The main reason seems to be the use of high quality food (wheat germs), which considerably increased fecundity. A new model with reduced fecundity was found to correspond well with the observed dynamics in a granary. The model of C. eruditus, including parameters from different sources, produced dynamics quite similar to the observed one. A simulation of biological control under laboratory conditions, on 45 g of wheat, showed that C. eruditus is able to control A. siro within the observed period. In contrast, simulation of the control in a granary showed a marked difference in comparison with the observed dynamics. The discrepancy is attributed to the effects of spatial factors, such as immigration. The predator-prey model developed here appears to be valid for the prediction of the local (within-patch) population dynamics of A. siro and C. eruditus on wheat grain at 20 °C and 80% RH.

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Individual and synergistic toxicity of solanaceous glycoalkaloids against two coleopteran stored-product insects

Toxicity of solanaceous glycoalkaloids against stored-grain insects was investigated under laboratory conditions. The total glycoalkaloids (TGAs), α-chaconine and α-solanine from potatoes, Solanum tuberosum L. and α-tomatine from tomatoes, Lycopersicon esculentum Mill. were isolated and tested in this bioassay. Their acute and residual toxicity were assessed against the rust red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), and the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae). All compounds were tested either individually or as binary mixtures. Results revealed considerable toxicity of the tested glycoalkaloids against the target insects. When adults of S. oryzae were exposed to a dry-film residue of these phytochemicals, the total glycoalkaloids (TGAs) fraction was the most toxic, followed by α-solanine, α-chaconine, and α-tomatine with LC_50s of (38.6 and 22.1), (48.2 and 38.9), (52.00 and 41.6), and (82.3 and 67.00) μg/cm² at 24 and 48 h post-treatment, respectively. The order of toxicity against T. castaneum in a descending order was TGAs > α-chaconine > α-solanine > α-tomatine. All compounds were more toxic when insects were fed grains treated with these phytochemicals (LC_50s of TGAs were 7.4 and 16.2 mg/kg grains at 48 h post-treatment against S. oryzae and T. castaneum, respectively. All compounds, particularly the TGAs, exhibited promising residual toxicity effects. Toxicity of glycoalkaloids was exceeded when tested as binary mixtures indicating their synergistic interaction. The study recommends the use of glycoalkaloids of Solanaceae as biorationals and natural leads to protect stored grains from insect infestation.     

Antimicrobial activity against <Emphasis Type="Italic">Streptococcus sobrinus</Emphasis> and glucosyltransferase inhibitory activity of taxifolin and some flavanonol rhamnosides from kempas (<Emphasis Type="Italic">Koompassia malaccensis</Emphasis>) extracts

Twenty plant materials collected from the islands of Java and Kalimantan in Indonesia were extracted with 50% aqueous ethanol (crude extract). The crude extracts were assayed for antimicrobial activities against Streptococcus sobrinus and for glucosyltransferase (GTase) inhibition. Fourteen extracts inhibited the growth of S. sobrinus by more than 50% and six extracts inhibited GTase activity by more than 50% at a concentration of 100 μg/ml. Koompassia malaccensis (kempas) extracts showed 90% depression of S. sobrinus growth and 80% inhibition of GTase activity at a concentration of 100 μg/ml. Kempas crude extracts were subjected to column chromatography using Sephadex LH-20 and then preparative high-performance liquid chromatography to isolate four compounds A, B, C, and D. These compounds were identified as taxifolin and the flavanonol rhamnoside isomers neoastilbin, astilbin, and isoastilbin, respectively, from ¹H and ¹³C nuclear magnetic resonance (NMR) spectra and other two-dimensional NMR techniques (COSY, HMBC, and HMQC). Each compound depressed the growth of S. sobrinus over a concentration range of 9.3242.7 μg/ml and showed GTase inhibitory activity with IC₅₀ values in the range 27.4–57.3 μg/ml. Taxifolin and flavanonol rhamnoside isomers isolated for the first time from kempas could be potent compounds for preventing dental caries. Part of this report was presented at the 57th Annual Meeting of the Japan Wood Research Society Conference, Hiroshima, 2007     

In vitro morphogenic response and metal accumulation in <Emphasis Type="Italic">Albizia lebbeck</Emphasis> (L.) cultures grown under metal stress

An efficient regeneration protocol for rapid mass propagation and uptake of heavy metals in Albizia lebbeck (L.), a fast growing, medicinally as well as economically important timber yielding tree was developed. Nodal segments derived from a 20-year-old tree were cultured on MS (Murashige and Skoog) medium supplemented with 10 μM 6-Benzyladenine (BA) and 1 μM α-Naphthalene acetic acid (NAA) showed optimum shoot regeneration frequency (76.6%), number of shoots (23.2 ± 0.28) per explant and shoot length (2.86 ± 0.08 cm) after 10 weeks of culture. After standardizing a reliable protocol for micropropagation, effects of ZnSO4 (0.06–0.48 mM), CuSO₄ (0.02–0.2 mM) and CdCl₂ (0.0001–0.001 mM) on shoot morphogenesis were also assessed. The regenerated shoots maintained on maintenance medium (MS + 10.0 μM BA + 1.0 μM NAA) containing ZnSO₄ (0.06 mM) showed maximum response in terms of shoot number (24.5 ± 0.83) and length (5.9 ± 0.05 cm) after 10 weeks of culture. Proline content showed an increasing trend while chlorophyll (a and b) content exhibited decreasing trend with an increased metal concentrations compared to MM cultures, and maximum increase in proline and decrease in chlorophyll content was recorded in cultures grown on Cd-enriched medium. Best rooting was accomplished on half strength MS medium with 2.0 μM IBA and ZnSO₄ (0.06 mM). The plantlets thus obtained were successfully hardened and transferred to greenhouse with 75% survival rate and exhibited normal morphological characteristics compared to donor plant.     

Comparative data on the insecticide resistance of <Emphasis Type="Italic">Anopheles</Emphasis> <Emphasis Type="Italic">albimanus</Emphasis> in relation to agricultural practices in northern Belize,CA

Anopheles albimanus Wiedemann is one of the primary vectors of malaria in northern Belize. The primary breeding sites for this species in Central America are fresh water wetlands that are found in close proximity to agriculture and, in particular, sugarcane fields. The use of insecticides and herbicides on these crops leads to the introduction of chemicals into the surrounding wetlands. The potential for the development of insecticide resistance is, therefore, quite high. A study was undertaken to obtain comparative data on the resistance status of An. albimanus in northern Belize in relation to agriculture practices. Larval surveys were conducted at four collection points in marshes juxtaposed to different crop types: Dubloon (DB)—control site located 300 m from any agriculture; Little Belize (LB)—mixed crop agricultural with some human settlements; and Chan Chen (CC) and Buena Vista (BV)—year round sugarcane production. Time mortality curves were obtained by exposing F1 larvae to DDT 1 μg/ml, malathion 1 μg/ml, and permethrin 0.05 μg/ml. Significant differences in mortality rates from the four sites were observed only to malathion. The DB sites contained larvae that were the most susceptible overall, in congruence with its distance from crops. Larvae from LB exhibited a medium level of tolerance. Finally, the two populations collected at the edge of sugarcane fields (CC and BV) exhibited the highest tolerance to malathion. These results represent first data on the impact of agriculture on the resistance status of malaria vectors in northern Belize. The effect of malathion on An. albimanus insecticide resistance reinforces the concerns of the potential impact of agriculture usage on the efficacy of vector control program.     

Micropropagation of <Emphasis Type="Italic">Salvadora</Emphasis><Emphasis Type="Italic">persica</Emphasis>-a tree of arid horticulture and forestry

A micropropagation method for Jaal (Salvadora persica)—a tree of arid horticulture and forestry has been developed. Nodal segments of fresh shoot sprouts originated from axillary buds obtained from a plant around 35–40 years old lopped plant were used as explants for establishment of in vitro cultures. Surface-sterilized explants produced optimum number of shoots through activation of axillary buds on Murashige and Skoog’s (MS) medium containing 8.88 μM BA (6-benzyladenine) + additives (25 mgl⁻¹ each of adenine sulphate, arginine, citric acid, 50 mgl⁻¹ ascorbic acid). The shoot multiplication was influenced by the successive transfer of the mother explants for 4–5 passages. The maximum number (23.1 ± 0.73 shoots per explant) of shoots were regenerated on MS supplemented with 1.11 μM BA + 1.16 μM Kn (Kinetin) + 0.54 μM NAA (α-naphthalene acetic acid). About 90% shoots pulse-treated with a combination of 2460.27 μM Indole-3-butyric acid (IBA) + 494.56 μM NOA (2-naphthoxy acetic acid) were rooted ex vitro on soilrite within 15–18 days. Over 80% cloned plantlets were hardened successfully in a green house and transferred to polybag/pots.     

Antioxidant properties and structural analysis of phenolic glucosides from bark of <Emphasis Type="Italic">Populus ussuriensis</Emphasis> Kom.

The methanol (MeOH) extract of Populus ussuriensis Kom. bark was analyzed for antioxidant assessing by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging potential. Among fractions using several solvents, the ethyl acetate (EtOAc) soluble fraction, which showed strong antioxidant activity (IC₅₀ 2.02 ± 0.01 μg/ml), was further purified by Thin layer chromatography (TLC) guided Sephadex LH-20 column chromatography. Three known phenolic glucosides, picein (I), salicortin (II), grandidentatin (III), and that of a new, 2-hydroxycyclohexyl-4′-O-p-coumaroyl-β-d-glucopyranoside (isograndidentatin A), were isolated and their structures were elucidated on the basis of physiochemical and spectroscopic methods. This was the first report of the chemical composition of P. ussuriensis bark. Phenolic glucosides III and IV exhibited strong antioxidant activities, with IC₅₀ values 6.73 ± 0.01 and 6.69 ± 0.01 μM, respectively, comparable to the control (α-tocopherol, IC₅₀ 6.80 ± 0.01 μM). P. ussuriensis bark EtOAc-soluble fraction and compounds III and IV could be used as biopreservatives in food applications as well as for cosmetic and medicinal preparations, to alleviate oxidative stress.