Tephrosia Vogelii Research Articles

Isoflavones from the seedpods of Tephrosia vogelii and pyrazoisopongaflavone with anti-inflammatory effects

Phytochemical investigation of Tephrosia vogelii seedpods led to the isolation of twelve compounds: vogelisoflavone A (1), vogelisoflavone B (2), isopongaflavone (3), onogenin, luteolin, 4′,7-dihydroxy-3′-methoxyflavanone, trans-p-hydroxycinnamic acid, tephrosin, 2-methoxygliricidol, dehydrorotenone, 6a,12a-dehydro-α-toxicarol and pinoresinol. Compounds 1 and 2 are reported as new natural products. Isopongaflavone (3) was structurally modified using hydrazine to pyrazoisopongaflavone (4). These compounds were characterized based on their NMR and HRESIMS data. Further, four compounds (1–4) were evaluated for their anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs). Treatment of the LPS-stimulated PBMCs with the compounds at a concentration of 100 μM suppressed the secretion of interleukin IL-1β interferon-gamma (IFN-γ), granulocyte macrophage-colony stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-α).

Isolation of the Tephrosia vogelii extract and rotenoids and their toxicity in the RTgill-W1 trout cell line and in zebrafish embryos

This study focused on identifying the rotenoids from the Tephrosia vogelli plant (fish-poison-bean), investigating the toxic potency of a crude T. vogelii extract and individual rotenoids (tephrosin, deguelin and rotenone) in vitro and in vivo and assessing the mode of action. A trout (Onychorynhis mykiss) gill epithelial cell line (RTgill-W1) was used to determine the cytotoxicity of rotenoids and effects on cell metabolism. Zebrafish (Danio rerio) aged from 3 h post fertilization (hpf) to 72 hpf were used for testing the developmental toxicity. The crude T. vogelii plant extract significantly decreased the cellular metabolic activity and was cytotoxic at lower concentrations (5 and 10 nM, respectively), while tephrosin, deguelin and rotenone showed these effects at concentrations ≥ 50 nM. The crude T. Vogelli extract had the highest toxic potency and induced adverse health effects in zebrafish including deformities and mortality at the lowest concentration (5 nM) compared to rotenone (10 nM) and deguelin and tephrosin (50 nM). These results indicate that the crude T. Vogelii extracts are highly potent and the bioactivity of these extracts warrant further investigation for their potential use to treat parasites in human and veterinary medicine and as a natural alternative to pesticides.

Field efficacy of entomopathogens and plant extracts on Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) infesting tomato in Rwanda

Following its outbreak in 2015, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) immediately became one of the major threats to the food chain in Rwanda and, therefore, sustainable management options are needed to address the situation. Two field trials were established on 3rd April and 28th June 2019 to study the efficacy of entomopathogens and plant extracts on T. absoluta infestation in Rwanda. Similar procedures were followed and nine treatments were evaluated, including: entomopathogenic nematodes (EPNs) (Steinernema sp. RW14-M-C2a-3 and Steinernema sp. RW14-M-C2a-3), commercial formulations of entomopathogenic fungi (EPFs) [Metatech®WP: Metarhizium anisopliae (Metsch.) Sorok, Strain FCM Ar 23B3), Beauvitech® WP: Beauveria bassiana (Bals.) Vuill., Strain J25], plant extracts of Tephrosia vogelii and Phytolacca dodecandra, azadirachtin 0.03% EC, imidacloprid as positive control and water as negative control. The entomopathogens and azadirachtin significantly reduced leaf and leaflet damages compared to the plant extracts and the controls. However, leaf damage increased with time and reached the maximum level (100%) in 9–10 weeks after transplanting in all the treatments. In both trials, the maximum leaflet damage observed with entomopathogens and azadirachtin in 10 weeks after transplanting varied between 59.7% and 74.7% with the marketable fruit yield of 12.4–16.2 t ha−1; while leaflet damage in positive control ranged 80.0%–92.1% with marketable yield of 3.0–3.5 t ha−1. Our results suggest that the entomopathogens and azadirachtin have the potential for use in integrated pest management of T. absoluta in Rwanda, but further studies are needed to incorporate them in the IPM program.

Growth, yield and fruit quality of tomato under different integrated management options against Tuta absoluta Meyrick

This study evaluated the effect of entomopathogens and plant extracts, used against Tuta absoluta, on growth, yield, and fruit quality of tomato. Two field trials were carried out in a randomised compled block design, replicated thrice. The treatments were Steinernema sp. RW14­M­C2a­3, Steinernema sp. RW14­M­C2a­3, Metatech®WP (Metarhizium anisopliae, Strain FCM Ar 23B3), Beauvitech®WP (Beauveria bassiana, Strain J25) as entomopathogens, Tephrosia vogelii and Phytolacca dodecandra as plant extracts, and azadirachtin 0.03% EC. Imidacloprid and water also were included as positive and negative controls, respectively. The best growth and yield parameters were recorded with the entomopathogens and azadirachtin, which were insignificantly different in most cases. The increase in yied of healthy fruit per plant (average of two trials) compared to the negative control (water spray) was 11.4, 10.8,10.1, 9.6, 3.96, 2.2, 11.7 and 2.4 folds for Steinernema sp. RW14M­C2a­3, Steinernema sp. RW14­M­C2a­3, Metatech®WP, Beauvitech WP, T. vogelii, P. dodecandra, azadirachtin, and imidacloprid, respectively. There was no significant difference in number of leaves per plant and fruit quality parameters. The entomopathogens and azadirachtin, which exhibited a capacity to enhance tomato growth and reduced yield losses due to T. absoluta, are recommended to be included in integrated pest management programme on tomato.

Short-term improved fallows of Tephrosia vogelii and Cajanus cajan enhanced maize productivity and soil chemical properties of a degraded fallow land in Southwestern Ethiopia

An improved fallow experiment was established in 2013 to examine the contribution of shrub legume species, Tephrosia vogelii and Cajanus cajan, in improving the productivity of a degraded tropical soil and crop yields compared with traditional fallow. The study was conducted on five farmers’ fields in southwestern Ethiopia laid out in randomized complete block design with farmers as replicates. After 2 years, the amount of aboveground biomass produced was 5–8 t ha−1 for Tephrosia and 3–5 t ha−1 for Cajanus. Maize grain yield was 80% higher for Tephrosia and 41% for Cajanus compared with the traditional fallow. The legume species significantly increased soil pH, organic carbon and total nitrogen levels compared with the natural fallow but there was no significant effect for available phosphorus. The magnitude of fallow benefit from Tephrosia in terms of yield advantage and nitrogen availability could be related to its high biomass production capacity compared to Cajanus. Fallowing with Tephrosia has the potential for improving productivity of degraded tropical soils. Farmers’ responses to the improved fallows were in general positive and their preference was Tephrosia fallow. Farmers can therefore use Tephrosia to enhance soil fertility by increasing N-levels, soil pH and organic matter of the soil. However, phosphate fertilizer is required as basal application to enhance N-fixation by legumes.

Effects of Selected Pesticidal Plants on Termites Affecting Maize Production in Arusha, Tanzania

Investigations under laboratory and field conditions were carried out with purpose of understanding the effects of pesticides of Cupressus lusitanica, Tephrosia vogelii, Eucalpytus dalrympleana, Lantana camara and Azadirachta indica in the control of termites which affect maize production in Arusha, Tanzania. Termites were collected before and during maize season of 2018 and identified at the Tropical Pesticides Research Institute (TPRI) laboratory. A total of 5279 out of 5307 termite species identified belong to genus Macrotermes, 23 species to genus Odontotermes and 5 species were unknown. The results entailed that the area is rich in species of genus Macrotermes. Moreover, concentrations i.e. 5 g, 10 g and 20 g of each botanical were tested for Macrotermes spp. mortality and repellency ability in the laboratory using a completely randomized design (CRD) with three replicates. The results showed that 98.33% Macrotermes spp. mortality was caused by T. vogelii followed by 93.33% recorded from E. dalrympleana after 24 hours. Besides, C. lusitanica repelled Macrotermes spp. by 97% followed by 95% recorded from T. vogelii and E. dalrympleana each. For field trials, 20 g of each botanical was applied using randomized complete block design (RCBD) with four replicates. The results obtained from field indicated that T. vogelii was more effective to protect maize with an average of 6 maize stands and 3.4 kg of dry total weight of maize grains next to positive control per plot. Also, average of 4 maize stands and 3 kg dry total weight of maize grains were recorded from treatments of E. dalrympleana and C. lusitanica each. Such results highlight the potential of developing bio-termiticides from T. vogelii, C. lusitanica and E. dalrympleana to control Macrotermes spp.

Comparative Effects of Aqueous and Freeze Dried Leaf Extracts of <i>Tephrosia vogelii</i> on <i>Heterobranchus longifilis</i> Juveniles Val. (Pisces: 1840)

The present study was carried out to evaluate the potential of the aqueous leaf and freeze-dried leaf extracts of Tephrosia vogelii as tranquilizers on an African catfish, Hetetobranchus longifilis post juveniles (mean weight 115.00±25.00g) obtained from wild stock. They were acclimatized under laboratory conditions for two weeks prior to the commencement of the experiment. The fish were fed once a day at 9.00 hours at 4% body weight during the period of acclimatization. Each tank containing acclimatization water was aerated to enhance dissolved oxygen, and water was changed daily to prevent metabolic waste build up. Experimental fish were starved for 24 hours prior to sedation to prevent regurgitation from the gastro-intestinal tract (GIT). Four healthy Hetetobranchus longifilis were selected randomly from both the control and treatment groups. Each fish was weighted and injected 0.05ml of aqueous and freeze-dried leaf extracts at concentrations of 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06g/l using №. 23 needle and a 2ml heparinized syringe. Injection was done intramuscularly (IM) at the dorsal saddle just above the lateral line behind the operculum. Fish in the control group were injected with distilled water. Injected fish were observed for behavioural responses. The result showed that H. longifilis injected with the freeze-dried leaf extract of T. vogelii passed sequentially through the first three stages of anaesthesia but could not attain total loss of equilibrium (stage 4 of anaesthsia). Behavioural responses included mucus secretion, slow and erratic swimming, excrement discharge, increase in opercular beat rate, strong retension of reflex action, partial loss of equilibrium and colour change. The induction time decreased with increasing concentration of the anaesthetic extract. The recovery time followed the reverse order. The opercular beat rates, before and after sedation in the treatment groups showed increase over that in the control group and it increased with increasing concentration. The result of the experiment with aqueous leaf extract showed that there was no significant difference in opercular beat rate after sedation in all centrations used (P>0.05). The result also showed that at higher concentration (0.06g/l) induction was time 44.67 seconds while at concentration 0.02g/l induction time was 83.70 seconds. In the case of the freeze-dried leaf extract of T. vogelii the induction at concentration 0.06g/l was 49.33 seconds while at concentration 0.02g/l induction time 76.67 seconds.

Antimicrobial activities of Tephrosia vogelii against selected pathogenic fungi and bacteria strains

ABSTRACTCandida albicans and Cryptococcus neoformans are dangerous pathogens causing fungal diseases. C. albicans and C. neoformans developed resistance to fungicides such as fluconazole. Similarly, pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Salmonella typhi have become resistant to antibiotcs such as methicillin. Thus, searching for alternative antimicrobial agents is inevitable. Tephrosia vogelii used traditionally for management of fungal and bacterial diseases is potential source of antimicrobial agents. It is in this vein that, antimicrobial activities of leaf and root extracts of T. vogelii were evaluated against C. albicans (ATCC 90028), C. neoformans (clinical isolate), S. aureus (ATCC25923), E. coli (ATCC29953), K. pneumoniae (ATCC 700603) and S. typhi (NCTC 8385). A two-fold serial dilution method using the sterilised 96 wells of polystyrene microlitre plates used to determine the minimum inhibitory concentration (MIC) of extracts. Hexane and dichloromethane extracts exhibited the lowest activity against fungi strains with MICs >10 mg/mL. Root and leaf methanolic extracts exhibited activity at MICs of 5 and 1.25 mg/mL, respectively, against both tested fungi. Dichloromethane and methanolic extracts exhibited antibacterial activity with MICs ranging from 2.5 - 10 mg/mL and 0.625 - 5 mg/mL, respectively. Antimicrobial activities of the extracts of T. vogelii revealed potentiality of bioactives against fungal and bacterial diseases.

Phytochemical Analysis of Tephrosia vogelii across East Africa Reveals Three Chemotypes that Influence Its Use as a Pesticidal Plant.

Tephrosia vogelii is a plant species chemically characterized by the presence of entomotoxic rotenoids and used widely across Africa as a botanical pesticide. Phytochemical analysis was conducted to establish the presence and abundance of the bioactive principles in this species across three countries in East Africa: Tanzania, Kenya, and Malawi. Analysis of methanolic extracts of foliar parts of T. vogelii revealed the occurrence of two distinct chemotypes that were separated by the presence of rotenoids in one, and flavanones and flavones that are not bioactive against insects on the other. Specifically, chemotype 1 contained deguelin as the major rotenoid along with tephrosin, and rotenone as a minor component, while these compounds were absent from chemotype 2, which contained previously reported flavanones and flavones including obovatin-3-O-methylether. Chemotype 3 contained a combination of the chemical profiles of both chemotype 1 and 2 suggesting a chemical hybrid. Plant samples identified as chemotype 1 showed chemical consistency across seasons and altitudes, except in the wet season where a significant difference was observed for samples in Tanzania. Since farmers are unable to determine the chemical content of material available care must be taken in promoting this species for pest management without first establishing efficacy. While phytochemical analysis serves as an important tool for quality control of pesticidal plants, where analytical facilities are not available simple bioassays could be developed to enable extension staff and farmers to determine the efficacy of their plants and ensure only effective materials are adopted.

Field assessment of the efficacy of Tephrosia vogelii leaf extracts for control of ticks on naturally infested cattle in the field condition.

Tephrosia vogelii (T. vogelii) is a known tropical leguminous herb for fixing nitrogen in the soil and as pesticide properties. Its crude leaf extract was evaluated as a natural acaricide to control ticks on naturally infested traditionally reared cattle in selected areas of Monze District of Zambia. Experimental animals were selected from herds of cattle with poor or no history of any conventional tick control and were divided into six treatment groups of five animals per set which were sprayed with 5, 10, 20 and 40% w/v of T. vogelii leaf extract bio-acaricide solution. A negative control group of five animals were sprayed with ordinary water, while a positive group with a commercial acaricide (Amitraz®) at a recommended dosage of 1:500 dilution. Half-body tick counts then doubled were conducted on each animal, before and at twenty-four hourly intervals of: 24 (1day), 48 (2days), 96 (3days), 192 (4days), 384 (5days) and 768 (6days) after treatment. The observed tick reductions were found to be statistically significant at all treatment levels (p value < 0.001). With this performance, there was evidence to show that the herbal extract was effective against ticks. The results showed significant and sustained efficacy T. vogelii extract from day 2 to day 6 after treatment. There was no significant difference at 5, 10, 20 and 40w/v in the observed efficacies between low and high concentrations of the bio-acaricide used. We conclude that T. vogelii could be used to spray animals against ticks, especially in low-income communities and also in setups where organic farming is practiced.

Analysis on safety assessment of Tephrosia vogelii Hook to Apis cerana cerana

Tephrosia vogelii Hook was excellent insecticidal plant, it was introduced into China and planted over a large area in Guangdong province. The main active components of T. vogelii was rotenone and it widely found in leaves and pods of T. vogelii. This paper study of the safety assessment of T. vogelii flowers to worker bees. In this paper, the content of rotenone in T. vogelii petal, nectar, pollen, pistil, and stamen samples were investigated by HPLC, and tested the toxicity of T. vogelii flowers for Apis cerana cerana during 24 h. The dissipation and dynamic of rotenone in A. c. cerana different biological compartments were investigated under indoor conditions during 24 h. The results showed, The LT50 of T. vogelii flowers to worker bees were collected from the eastern, western, southern, northern and top were 13.95, 24.17, 12.55, 26.48, and 18.84 h, the haemolymph of worker bees have the highest content of rotenone, the least accumulation of rotenone in workers bee's thorax, and the rate of dissipation was slowly during the whole study. In conclusion, the results showed the T. vogelii create security risks to worker bees under some ecosystems.

Efficacy of homemade botanical insecticides based on traditional knowledge. A review

Homemade botanical insecticides are widely used by subsistence and transitional farmers in low-income countries. Their use is often driven by the limited availability or cost of commercial pesticides. Homemade botanical insecticides are often recommended by agricultural extension services and some development organizations. However, this could be questioned because scientific evidence of their efficacy and safety may not be available or accessible. Although botanicals with insecticidal properties have been widely studied, a synthesis focusing specifically on homemade preparations used in realistic field or storage conditions is missing. In this paper, we review efficacy assessments of botanicals used to prepare homemade insecticides. This covers twelve botanicals recommended by national extension partners in 20 countries within the global agricultural Plantwise program. These are as follows: garlic (Allium sativum), neem (Azadirachta indica), chili pepper (Capsicum spp.), Siam weed (Chromolaena odorata), mother of cocoa (Gliricidia sepium), chinaberry (Melia azedarach), moringa (Moringa oleifera), tobacco (Nicotiana tabacum), clove basil (Ocimum gratissimum), tephrosia (Tephrosia vogelii), tree marigold (Tithonia diversifolia), and bitter leaf (Vernonia amygdalina). This review shows that (1) all the selected botanicals contain active ingredients with insecticidal, antifeedant, or repellent properties, and (2) homemade insecticides based on all the selected botanicals have been used with some success to control pests or prevent damage, although efficacy was variable and often lower than the positive controls (synthetic pesticides). Factors affecting the efficacy of homemade botanical insecticide include variation in active ingredient content and concentration in plant material, as well as variation in the preparation process. In conclusion, there is some evidence that homemade botanical insecticides could contribute to reducing losses in food production. Since further research is needed to better understand their variable efficacy and potential health and environmental risks, those who promote the use of homemade botanical insecticides should also communicate those “unknowns” to the farmers who use such products.

Effect of soil amendment with Gliricidia sepium and Tephrosia vogelii biomass on maize yield at Makoka in Malawi

Several studies assessing the effect of leguminous tree biomass such as Gliricidia sepium and Tephrosia vogelii on maize yield have been undertaken. There has been limited knowledge on the efficacy of leguminous tree biomass on maize yield when grown after a crop with a high nitrogen (N) demand. One such crop is cotton. The current study was undertaken with the objective of determining the efficacy of either gliricidia or tephrosia biomass application with or without inorganic fertilizer on maize yield cultivated after cotton and also after land fallowing. Significant variations in grain yield (P = 0.0038) were obtained in the second cropping season (2016/17) but not in the first cropping season (2014/15), except maize stover (P < 0.0016). Significant variations were also obtained during 2016/17 season with respect to maize cob yield (P < 0.0041) and stover yield (P = 0.0062). Grain yield was significantly higher where inorganic fertilizer was applied with gliricidia biomass than where inorganic fertilizer was applied alone. A similar trend was also observed during the first cropping season though not significantly different. Lower grain yield was obtained when cotton crop preceded maize crop indicating a need for a higher N fertilizer dose for maize crop cultivated after cotton. Application of a half dose of inorganic fertilizer together with gliricidia biomass showed high and steady grain yield over the yield obtained when inorganic fertilizer was applied alone. It is concluded that soil fertility amendment with inorganic fertilizer is needed after a cotton crop. Also, the use of a half dose of inorganic N fertilizer with gliricidia was effective, suggesting that a full dose with gliricidia biomass was rather surplus to the requirements for maize production. Our study shows that farmers can save nearly half of the inorganic N fertilizer required by maize under gliricidia-maize system.

Comparative Toxicity of Aqueous Extract of Tephrosia Vogelii and Some Synthetic Insecticides in the Control of Insect Pests of Cucumber (Cucumis sativus L.)

Comparative Toxicity of Aqueous Extract of Tephrosia Vogelii and Some Synthetic Insecticides in the Control of Insect Pests of Cucumber (Cucumis sativus L.)

Deletion of rRNA Operons of Sinorhizobium fredii Strain NGR234 and Impact on Symbiosis With Legumes.

During their lifecycle, from free-living soil bacteria to endosymbiotic nitrogen-fixing bacteroids of legumes, rhizobia must colonize, and cope with environments where nutrient concentrations and compositions vary greatly. Bacterial colonization of legume rhizospheres and of root surfaces is subject to a fierce competition for plant exudates. By contrast root nodules offer to rhizobia sheltered nutrient-rich environments within which the cells that successfully propagated via infection threads can rapidly multiply. To explore the effects on symbiosis of a slower rhizobia growth and metabolism, we deleted one or two copies of the three functional rRNA operons of the promiscuous Sinorhizobium fredii strain NGR234 and examined the impact of these mutations on free-living and symbiotic lifestyles. Strains with two functional rRNA operons (NGRΔrRNA1 and NGRΔrRNA3) grew almost as rapidly as NGR234, and NGRΔrRNA1 was as proficient as the parent strain on all of the five legume species tested. By contrast, the NGRΔrRNA1,3 double mutant, which carried a single rRNA operon and grew significantly slower than NGR234, had a reduced symbiotic proficiency on Cajanus cajan, Macroptilium atropurpureum, Tephrosia vogelii, and Vigna unguiculata. In addition, while NGRΔrRNA1 and NGR234 equally competed for nodulation of V. unguiculata, strain NGRΔrRNA1,3 was clearly outcompeted by wild-type. Surprisingly, on Leucaena leucocephala, NGRΔrRNA1,3 was the most proficient strain and competed equally NGR234 for nodule occupation. Together, these results indicate that for strains with otherwise identical repertoires of symbiotic genes, a faster growth on roots and/or inside plant tissues may contribute to secure access to nodules of some hosts. By contrast, other legumes such as L. leucocephala appear as less selective and capable of providing symbiotic environments susceptible to accommodate strains with a broader spectrum of competences.

Toxicity of four kind plant extracts (Ageratum conyzoides L., Barringtonia asiatica (L.) Kurz., Melia azedarach L., Tephrosia vogelii Hook F.) against brown planthopper (Nilaparvata lugens STAL.)

One of the main pests that attack rice plants is the brown planthopper (BPH), Nilaparvata lugens. Awareness of the negative effects of synthetic insecticides that have been used to control BPH has encouraged the use of natural resources for crop protection. The plant is one of natural source that can be used in the crop protection. Some plant species that have been known to have insecticidal activities include Ageratum conyzoides (Asteraceae), Barringtonia asiatica (Lechytidaceae), Melia azedarach (Meliaceae) and Tephrosia vogelii (Fabaceae). In this study toxicity test of the plant extracts was carried out on BPH, and its phytotoxicity was observed in rice plants. In the toxicity test of the plant extracts against N. lugens and the phytotoxicity test on rice plants used 2 concentrations namely 0.1% and 0.5% from each plant extract, while the antioviposition test used a concentration of 0.5%. The results showed that the methanolic extract of T. vogelii with a concentration of 0.5% caused the highest mortality of brown plant hopper nymphs of 42.5% and at concentration of 0.5% the four plant extracts did not inhibit oviposition activity of N. lugens female and did not phytotoxic on rice plants.Keywords: Toxicity, anti oviposition, plant extract, brown planthopper

Different Plant Extracts against &amp;lt;i&amp;gt;Phytophthora infestans&amp;lt;/i&amp;gt; (Mont.) de Bary in Tomato &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt;

The objective of this study was to evaluate the efficacy of plant extracts in managing late blight disease in tomato, in vitro. Crude extracts were from Plectranthus barbatus, Tephrosia vogelii, Sphaeranthus suaveolens and Lantana camara. These were compared with commercial formulations Otiva fungicide and untreated as negative control. Their effectiveness was determined by measuring the inhibition zone of the mycelial growth of the pathogen recorded in triplicate at 48 hours and 72 hours. The results showed significant differences (P ≤ 0.001) among the extracting solvents on percentage inhibition of Phytophthora infestans. Methanol was superior in inhibiting the growth of mycelial growth of P. infestans as compared with ethyl acetate. Furthermore, all plants tested showed antifungal activity against P. infestans. The P. barbatus, L. camara and S. suaveolens were comparable with the commercial fungicide in inhibiting the growth of P. infestans. In this study, T. vogelii extract showed poor results in inhibiting the mycelial growth of P. infestans as compared with other plant extracts. Also, it was observed that, there were significant (P < 0.05) interactive effects between solvent and plant extracts and between incubation time and plant extracts.

Storage Temperature of Botanical Insecticide Mixture Formulations and Its Activity Againsts Crocidolomia pavonana (F.) (Lepidoptera: Crambidae)

The purpose of this research was to evaluate the safety of mixture formulations of Tephrosia vogelii and Piper aduncum at various storage temperatures and their insecticidal activity against C. pavonana larvae. Formulations were made from T. vogelii and P. aduncum (1:5) in emulsifiable concentrate (EC) and wettable powder (WP) form. Both formulations have strong insecticidal activity against C. pavonana. This research used a randomized completed design in different temperature treatments. Insecticidal activity of formulations after storage was tested against C. pavonana. The treatments were done using deep leaf method in 5 concentrations and 5 replications. The results showed that LC95 value of EC formulation after storage at condition: below 4°C, room temperature, and 40°C were 0.19%, 0.34% and 0.21% respectively. Based on LC95 value of EC formulation from each treatment, indicated that EC formulation after storage could hold insecticidal activity as good as insecticidal activity before storage due to LC95 value after storage relatively lower than LC95 value before storage (0.35%). In the contrary, WP formulation activity was significantly decreased in all treatments compared to WP formulation activity before storage based on LC95 value.

English

The percentage yield of rotenone extracted from Tephrosia vogelii leaves and seeds was investigated. Ten samples of well ground leaves and seeds were each subjected to extraction in soxhlet extraction system using trichloromethane, ethanol and methanol solvents for 24 h at room temperature. The maximum absorption wavelength of rotenone was determined using Ultra violet-visible spectrophotometer. Different solvent extracts were quantified using high performance liquid chromatography instruments fitted with Ultra Violet detector and their yield expressed as percentage rotenone. Trichloromethane recorded the highest rotenone yield from both leaves (8.3 and seeds 2.7%) compared to the other two solvents. Ethanol was second with 5.9% in leaves and 1.9% in seeds while methanol had 4.8% in leaves and 1.6% in seeds. In general, the leaves extracts were found to have a higher rotenone percentage yield by an average factor of 3 compared to seeds. Rotenone can be commercially extracted from T. Vogelii using ethanol that is locally available to complement natural pyrethrum insecticide industry. Key words: Rotenone, Tephrosia vogelii, solvents, seeds, leaves.

Pesticidal Plant Extracts Improve Yield and Reduce Insect Pests on Legume Crops Without Harming Beneficial Arthropods.

In the fight against arthropod crop pests using plant secondary metabolites, most research has focussed on the identification of bioactive molecules. Several hundred candidate plant species and compounds are now known to have pesticidal properties against a range of arthropod pest species. Despite this growing body of research, few natural products are commercialized for pest management whilst on-farm use of existing botanically-based pesticides remains a small, but growing, component of crop protection practice. Uptake of natural pesticides is at least partly constrained by limited data on the trade-offs of their use on farm. The research presented here assessed the potential trade-offs of using pesticidal plant extracts on legume crop yields and the regulating ecosystem services of natural pests enemies. The application of six established pesticidal plants (Bidens pilosa, Lantana camara, Lippia javanica, Tephrosia vogelii, Tithonia diversifolia, and Vernonia amygdalina) were compared to positive and negative controls for their impact on yields of bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and pigeon pea (Cajanus cajan) crops and the abundance of key indicator pest and predatory arthropod species. Analysis of field trials showed that pesticidal plant treatments often resulted in crop yields that were comparable to the use of a synthetic pesticide (lambda-cyhalothrin). The best-performing plant species were T. vogelii, T. diversifolia, and L. javanica. The abundance of pests was very low when using the synthetic pesticide, whilst the plant extracts generally had a higher number of pests than the synthetic but lower numbers than observed on the negative controls. Beneficial arthropod numbers were low with synthetic treated crops, whereas the pesticidal plant treatments appeared to have little effect on beneficials when compared to the negative controls. The outcomes of this research suggest that using extracts of pesticidal plants to control pests can be as effective as synthetic insecticides in terms of crop yields while tritrophic effects were reduced, conserving the non-target arthropods that provide important ecosystem services such as pollination and pest regulation. Thus managing crop pests using plant secondary metabolites can be more easily integrated in to agro-ecologically sustainable crop production systems.