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1.
The nematicidal effect of Pseudomonas fluorescens, Paecilomyces lilacinus, Pichia guilliermondii and Calothrix parietina singly or in combination was tested against root-knot nematode, Meloidogyne incognita. Treatments with P. fluorescens and P. lilacinus caused mortality of M. incognita as 45% and 30% of juveniles after 48 h of exposures, respectively compared to water control in vitro. Under greenhouse conditions, all treatments reduced the disease severity and enhanced plant growth compared to untreated control. Application of P. fluorescens, P. lilacinus and P. guilliermondii Moh 10 was more effective compared to C. parietina. There was a negative interaction between C. parietina and either P. lilacinus or P. guilliermondii. Fresh and dry weight of shoots and roots of plants were significantly reduced as a result of infection with M. incognita, however application of biocontrol agents singly or in mix recovered this reduction. Moreover, they enhanced the growth parameters compared with the control. Our results proved that application of different biocontrol agents (P. fluorescens, P. lilacinus and P. guilliermondii) not only has a lethal effect on nematode, but also enhances the plant growth, supplying many nutritional elements and induction the systemic resistance in plants. Presence of C. parietina as a soil inhabitant cyanobacterium could antagonize biocontrol agents leading to the reduction of their practical efficiency in soil.  相似文献   

2.
Significant areas of rain-fed rice in the Sahel, savannah and derived savannah zones of sub-Saharan Africa (SSA), Madagascar and other Indian Ocean Islands are infested by parasitic weeds. The affected area accommodates some of the poorest farmers of the world. Without appropriate management parasitic weeds in rice are expected to increase in importance in SSA due to their general invasive nature and their abilities to adapt to changing conditions such as imposed by predicted climate changes. The most important parasitic weeds in rice are: Striga hermonthica, Striga asiatica, Striga aspera and Rhamphicarpa fistulosa. The first two are primarily found in free-draining uplands while S. aspera is also found on hydromorphic soils and R. fistulosa is restricted to unimproved lowlands including inland valleys. As parasitic weeds are typical production constraints in subsistence rice production, targeting them would directly contribute to poverty alleviation and food security. This paper provides an overview of the problems caused by parasitic weeds in rice and discusses management options and opportunities for research for development.  相似文献   

3.
The fungus Fusarium guttiforme (Syn. F. subglutinans f. sp. ananas) is responsible for fusariosis, one of the main phytosanitary threats to pineapple (Ananas comosus var. comosus). A structural study comparing epidermal differences in pineapple cultivars resistant and susceptible to fusariosis was performed, relating properties of the epidermis to known susceptibility to the disease. The basal, non-chlorophylled, portions of mature leaves of pineapple plants were analyzed by light and electron microscopy. All cultivars showed common morpho-anatomic aspects characteristic of Bromeliaceae, such as scutiform scales and unstratified epidermis. However, cultivar Vitoria (resistant) had less scales than cultivars Smooth Cayenne (susceptible, intermediate severity) and Perola (susceptible, with extreme severity of fusariosis symptoms). Inoculation of conidia suspension (105 conidia ml−1) of the fungus F. guttiforme to leaves and harvesting 24 h later yielded numbers of viable colonies related to the density of leaf scales. This suggests that scales can act as havens for fungal conidia and favour the epiphytic stage of the fungus on pineapple plants, and are involved in the interaction of plant and pathogen. A reduction in scale numbers was related to lower infection levels and is relevant to the future breeding programme for development of new pineapple cultivars resistant to fusariosis and their involvement in integrated control strategies.  相似文献   

4.
Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD50) of C. curvignathus was 945 mg/kg, whereas LD50 value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices.  相似文献   

5.
Species of Trichocomaceae occur commonly and are important to both industry and medicine. They are associated with food spoilage and mycotoxin production and can occur in the indoor environment, causing health hazards by the formation of β-glucans, mycotoxins and surface proteins. Some species are opportunistic pathogens, while others are exploited in biotechnology for the production of enzymes, antibiotics and other products. Penicillium belongs phylogenetically to Trichocomaceae and more than 250 species are currently accepted in this genus. In this study, we investigated the relationship of Penicillium to other genera of Trichocomaceae and studied in detail the phylogeny of the genus itself. In order to study these relationships, partial RPB1, RPB2 (RNA polymerase II genes), Tsr1 (putative ribosome biogenesis protein) and Cct8 (putative chaperonin complex component TCP-1) gene sequences were obtained. The Trichocomaceae are divided in three separate families: Aspergillaceae, Thermoascaceae and Trichocomaceae. The Aspergillaceae are characterised by the formation flask-shaped or cylindrical phialides, asci produced inside cleistothecia or surrounded by Hülle cells and mainly ascospores with a furrow or slit, while the Trichocomaceae are defined by the formation of lanceolate phialides, asci borne within a tuft or layer of loose hyphae and ascospores lacking a slit. Thermoascus and Paecilomyces, both members of Thermoascaceae, also form ascospores lacking a furrow or slit, but are differentiated from Trichocomaceae by the production of asci from croziers and their thermotolerant or thermophilic nature. Phylogenetic analysis shows that Penicillium is polyphyletic. The genus is re-defined and a monophyletic genus for both anamorphs and teleomorphs is created (Penicillium sensu stricto). The genera Thysanophora, Eupenicillium, Chromocleista, Hemicarpenteles and Torulomyces belong in Penicilliums. str. and new combinations for the species belonging to these genera are proposed. Analysis of Penicillium below genus rank revealed the presence of 25 clades. A new classification system including both anamorph and teleomorph species is proposed and these 25 clades are treated here as sections. An overview of species belonging to each section is presented. TAXONOMIC NOVELTIES: New sections, all in Penicillium: sect. Sclerotiora Houbraken & Samson, sect. Charlesia Houbraken & Samson, sect. Thysanophora Houbraken & Samson,sect. Ochrosalmonea Houbraken & Samson, sect. Cinnamopurpurea Houbraken & Samson, Fracta Houbraken & Samson, sect. Stolkia Houbraken & Samson, sect. Gracilenta Houbraken & Samson, sect. Citrina Houbraken & Samson, sect. Turbata Houbraken & Samson, sect. Paradoxa Houbraken & Samson, sect. Canescentia Houbraken & Samson. New combinations:Penicillium asymmetricum (Subramanian & Sudha) Houbraken & Samson, P. bovifimosum (Tuthill & Frisvad) Houbraken & Samson, P. glaucoalbidum (Desmazières) Houbraken & Samson, P. laeve (K. Ando & Manoch) Houbraken & Samson, P. longisporum (Kendrick) Houbraken & Samson, P. malachiteum (Yaguchi & Udagawa) Houbraken & Samson, P. ovatum (K. Ando & Nawawi) Houbraken & Samson, P. parviverrucosum (K. Ando & Pitt) Houbraken & Samson, P. saturniforme (Wang & Zhuang) Houbraken & Samson, P. taiwanense (Matsushima) Houbraken & Samson. New names:Penicillium coniferophilum Houbraken & Samson, P. hennebertii Houbraken & Samson, P. melanostipe Houbraken & Samson, P. porphyreum Houbraken & Samson.  相似文献   

6.
The present investigation was conducted at Vittal, Karnataka, India during 2004-2007 to study the feasibility of intercropping of medicinal and aromatic plants (MAPs) in arecanut plantation. The results revealed that MAPs can be successfully grown as intercrops in arecanut plantation with increased productivity and net income per unit area. Kernel equivalent yield of MAPs varied between 272 kg ha−1 in case of Piper longum to 1218 kg ha−1 in Cymbopogon flexuosus. Pooled data indicated that Asparagus racemosus produced fresh root yield of 10,666 kg ha−1 of arecanut plantation and contributed to maximum kernel equivalent yield of 1524 kg ha−1 among all medicinal and aromatic plants. Intercropping of MAPs in arecanut was found economical. The net return per rupee investment was highest in C. flexuosus (4.25) followed by Bacopa monnieri (3.64), Ocimum basilicum (3.46) and Artemisia pallens (3.12). The total system productivity of arecanut + MAPs intercropping system varied from 2990 to 4144 kg ha−1. Arecanut + O. basilicum intercropping system registered significantly higher production efficiency 8.2 kg ha−1 day−1 than other systems. Intercropping of MAPs had more positive effect on soil pH in arecanut based cropping system. The soil pH was 5.6 in 2004 and it was 0.3-0.9 units higher in 2007. Soil organic carbon (SOC) content varied significantly due to intercropping of MAPs at the end of experiment. The SOC content increased in Aloe vera, A. pallens, P. longum and B. monnieri, while it depleted in grasses and rhizomatic MAPs. Based on demand and marketing opportunities for MAPs, farmers are advised to grow aromatic plants in large areas on a community basis to meet huge industrial demand and variety of medicinal crops in small areas to meet the requirement of traditional systems of medicine.  相似文献   

7.
Marine macrophytes contain a variety of biologically active compounds, some reported to have antiprotozoal activity in vitro. As a part of a screening program to search for new natural antiprotozoals, we screened hydroalcoholic and ethyl acetate extracts of 20 species of seaweeds from three phyla (Rhodophyta, Heterokontophyta and Chlorophyta), sampled along the Normandy (France) coast. We tested them in vitro against the protozoa responsible for three major endemic parasitic diseases: Plasmodium falciparum, Leishmania donovani and Trypanosoma cruzi. The selectivity of the extracts was also evaluated by testing on a mammalian cell line (L6 cells). Ethyl acetate extracts were more active than hydroalcoholic ones. Activity against T. cruzi and L. donovani was non-existent to average, but almost half the extracts showed good activity against P. falciparum. The ethyl acetate extract of Mastocarpus stellatus showed the best antiplasmodial activity as well as the best selectivity index (IC(50) = 2.8 μg/mL; SI > 30). Interestingly, a red algae species, which shares phylogenetic origins with P. falciparum, showed the best antiplasmodial activity. This study is the first to report comparative antiprotozoal activity of French marine algae. Some of the species studied here have not previously been biologically evaluated.  相似文献   

8.
The structures, names, bioactivities and references of 105 natural products obtained from gorgonian corals belonging to the family Plexauridae with an Indo-Pacific distribution are described in this review. All compounds mentioned in this review were obtained from gorgonian corals belonging to the genera Astrogorgia, Bebryce, Echinomuricea, Euplexaura and Menella.  相似文献   

9.
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10.
The population dynamics of Xanthomonas campestris pv. vitians (Xcv) was studied both externally and internally in lettuce, tomato and pepper plants. In addition, the application of bactericides during transplant production period was carried out for the management of bacterial leaf spot of lettuce under greenhouse conditions. Epiphytic populations of Xcv were recovered on leaves of lettuce plants (105 CFU/g) 5 weeks after sprayed than the other plant species when inoculated with 108 CFU/ml of Xcv. When plants of each crop species infiltrated with the bacterium at 105 CFU/ml, the highest populations were developed in lettuce (108 CFU/cm2) followed by pepper with 106 CFU/cm2 and tomato with 105 CFU/cm2 10-days after infiltration. Application of a mixture of Maneb and Kocide or Kocide alone as a foliar spray on lettuce significantly reduced the incidence and disease severity of bacterial leaf spot by 29 and 27% respectively. Spread of the bacterium and development of the disease may partly be managed by avoiding intercropping of these plants commonly grown in close proximity to lettuce. For the management of leaf-associated populations of Xcv in lettuce, use of a mixture of Maneb and Kocide is advocated to minimize the effect of attacks.  相似文献   

11.
Transgenically expressed Bacillus thuringiensis insecticidal-protein Cry1Ab was quantified in target tissues of insect feeding of several YieldGard® corn hybrids. The Cry1Ab protein is intended to protect corn plants from two economically important stem borers, Chilo partellus and Sesamia inferens. A total of seven YieldGard hybrids, all with MON810 event, were field-tested in a total of fourteen locations during the dry season (October–March) of 2005/2006 and wet season (May–October) of 2006. S. inferens and C. partellus oviposit on leaves of young corn plants, 15–60 days after emergence (DAE). The neonates initially feed by scraping the leaf lamina before migrating to bore into the stem. Thus high concentrations of Cry1Ab in whorl leaf and stem tissues would ensure effective control of the borers. The mean tissue Cry1Ab concentrations during the oviposition window of the borers (15–60 DAE), ranged from 50.05 to 21.01 ppm in whorl leaf, and between 9.26 and 3.47 ppm in stem tissue during the same period in the dry season of 2005/06. Similarly, Cry1Ab concentrations in whorl leaf and stem between 15 and 60 DAE during the wet season of 2006 ranged between 19.30 to 11.08 and 14.28 to 4.69 ppm, respectively. The baseline-sensitivity data of these insects to Cry1Ab in laboratory assays was determined. The concentrations of Cry1Ab in the target tissues as studied in seven YieldGard hybrids tested suggest effective management of the two borers. This paper also provides a summary of the expression of the Cry1Ab gene in various genetic backgrounds.  相似文献   

12.
Root nodulating Sinorhizobium fredii KCC5 and Pseudomonas fluorescens LPK2 were isolated from nodules of Cajanus cajan and disease suppressive soil of tomato rhizosphere, respectively. Both strains produced IAA, siderophore, solubilized insoluble phosphate, showed chitinase and β-1,3-glucanase activities, and strongly inhibited the growth of Fusarium udum. It also caused degradation and digestion of cell wall components, resulting in hyphal perforations, empty cell (halo) formation, shrinking and lysis of fungal mycelia along with significant degeneration of conidia. LPK2 produced volatile cyanogen (HCN). Combinations of S. fredii KCC5 and P. fluorescens LPK2 with half dose of chemical fertilizers showed a significant increase in seed germination (94%) while seed germination with co-inoculated strains (KCC5 + LPK2), KCC5 and LPK2 alone was 90, 84 and 82% respectively as compared to control 77%. After 120 days of sowing, per plant number of pods, nodules, shoot length, root length, shoot weight and root weight were greater for the combination with half dose of chemical fertilizers compared to the control. Combinations of S. fredii KCC5 and P. fluorescens LPK2 with half dose of chemical fertilizers resulted in an 82% increase in grain yield per hectare compared to the control. Both strains KCC5 and LPK2 led to proto-cooperation as evidenced by synergism, aggressive colonization of the roots, and enhanced growth, suggesting potential biocontrol efficacy against Fusarium wilt in C. cajan.  相似文献   

13.
During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere with the agr quorum sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII, the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA). To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium.  相似文献   

14.
Camelina (Camelina sativa), guayule (Parthenium argentatum), lesquerella (Physaria fendleri), and vernonia (Centrapalus pauciflorus [formerly Vernonia galamensis]) are either under limited commercial production or being developed for production in the southwestern USA. Insect pests are a potential economic threat to all these new crops, with Lygus hesperus, the western tarnished plant bug, among the most prominent due to its regional abundance and propensity to feed on reproductive plant tissue. The objectives of this study were to establish baseline data on the feeding behavior and potential impact of L. hesperus on camelina, guayule, lesquerella and vernonia. Behavioral observations of adult females and males, and nymphs of this insect were made in the laboratory. Insects spent ≈35% of their time either probing (=tasting) or feeding on various reproductive and vegetative tissues of guayule, lesquerella or vernonia, but only 20% on camelina. When insects did probe and feed they preferred reproductive tissues, primarily flowers and siliques/achenes, and there were differences in these behaviors relative to crop but not generally to insect stage or sex. Insects probed and fed more on flower tissue of guayule and vernonia compared with camelina and lesquerella, and more on siliques of lesquerella compared with achenes of vernonia. When probing and feeding on vegetative tissue, there was generally a preference for stems compared with leaves in all crops except guayule. Results show that L. hesperus will readily feed on the economically important tissues of all crops, and although research has shown that this feeding did not consistently affect lesquerella yield, further work will be needed to determine if such feeding poses a risk to commercial production of camelina, guayule or vernonia.  相似文献   

15.
The essential oils obtained by hydrodistillation from leaves of Chinese native Cryptomeria japonica and Cryptomeria fortunei were analyzed by GC and GC-MS. Fifty-seven compounds were identified in the essential oils of C. japonica with α-elemol (20.12%), kaur-16-ene (14.84%), β-phellandrene (5.97%), β-elemene (5.87%), α-eudesmol (5.62%) and β-eudesmol (5.03%) as main constituents. Forty components were identified in the oil of C. fortunei with kaurene (34.04%), α-elemol (13.34%), γ-eudesmol (10.80%), β-eudesmol (10.16%), α-pinene (2.75%) and γ-cadinene (1.92%) as the most abundant components. This study demonstrated the occurrence of α-elemol chemotype in C. japonica and kaurene chemotype in C. fortunei from China. The essential oil compositions of two Cryptomeria samples were shown that they can be used for green plant protection, pharmaceutical, perfume and food industries.  相似文献   

16.
The wblAso gene functions as a global regulatory gene in a negative manner in deepsea-derived Streptomyces somaliensis SCSIO ZH66. A new dioic acid (1) as well as two known butenolides (2 and 3) were isolated from the ΔwblAso mutant strain of S. somaliensis SCSIO ZH66. The structure of 1 was elucidated by a combination of spectroscopic analyses, including MS and NMR techniques. In the cell growth inhibitory evaluation, compound 3 exhibited moderate activity against the human hepatic carcinoma cell line (Huh7.5) with an IC50 value of 19.4 μg/mL, while compounds 1 and 2 showed null activity up to 100 μg/mL.  相似文献   

17.
Curcuma amada Roxb. (family Zingiberaceae), is gaining global attention as potential source of new drug molecule(s) as it is credited with compounds having remarkable pharmacological properties. Recognizing the risk of loss of genetic variability of C. amada in response to imprudent exploitation of the natural resources coupled with unsystematic cultivation practices, preservation of its genetic resources has attracted the current research attention. The present study exploited the multifarious properties of Luffa sponge (i.e. sound physical strength, stability in texture/shape over wide pH range and repeated autoclaving, cost effective availability, etc.) as a novel matrix for synthetic seed conservation. In this study, we have evaluated the consequences of the presence of two fungicides, namely - bavistin and rosebengal, in the gel matrix as well as in the Luffa sponge for conservation of contamination free germplasm of C. amada. A maximum of 50% and 75% regrowth could be recorded amongst rosebengal and bavistin containing synthetic seeds respectively after 4 weeks of plating on plant growth regulator-free MS medium. Further growth of the encapsulated microshoots was significantly impeded by the presence of rosebengal within the synthetic seeds. On the contrary, the bavistin containing synthetic seeds demonstrated five times better regeneration ability to contamination-free shoots. A total of 78% survival was achieved upon transfer of these healthy plantlets to glass-house. RAPD fingerprinting revealed 84.62% genetic similarity between randomly selected synthetic seed derived plantlets. This report strengthened the vital conservation approach of C. amada using inexpensive Luffa sponge as storage matrix and bavistin for eradication of contaminations.  相似文献   

18.
Sorghum accessions from Uganda were evaluated for grain mold and anthracnose resistance during the 2005 and 2006 growing seasons at the Texas A&M University Research Farm, near College Station, TX. Accession PI534117 and SC719-11E exhibited the lowest grain mold severities of 2.4, whereas, accessions PI534117, PI534144, PI576337, PI297199, PI533833, and PI297210, with SC748-5 were highly resistant to anthracnose in both years. Accessions PI534117, PI297134, PI297156 exhibited low grain mold severities in 2006. Significant negative correlation was recorded between grain mold and percent germination and high temperature in both years. In 2006, daily precipitation recorded significant positive correlation with grain mold. The seed mycoflora was analyzed across sorghum lines and treatments. In 2005, Curvularia lunata and Fusarium thapsinum were the most frequently recovered fungal species with 31 and 21% incidence, respectively, followed by Alternaria spp. (19%) and F. semitectum (13%). In 2006, predominant colonizers were F. thapsinum (58%), followed by Alternaria and F. semitectum with 15 and 10, percent respectively, while C. lunata had a 6% incidence. In this study, PI534117 holds promise for multiple disease resistance, as it had the lowest disease severity of grain mold and was highly resistant to anthracnose in both years. It also has a high germination rate, a high seed weight, and its short stature is more advantageous for the new A-line conversion program.  相似文献   

19.
Sclerotinia rot caused by the fungus Sclerotinia sclerotiorum is one of the most serious and damaging diseases of oilseed rape and there is keen worldwide interest to identify Brassica genotypes with resistance to this pathogen. Complete resistance against this pathogen has not been reported in the field, with only partial resistance being observed in some Brassica genotypes. Introgression lines were developed following hybridization of three wild crucifers (viz. Erucastrum cardaminoides, Diplotaxis tenuisiliqua and E. abyssinicum) with B. napus or B. juncea. Their resistance responses were characterized by using a stem inoculation test. Seed of 54 lines of B. napus and B. juncea obtained from Australia, India and China through an Australian Centre for International Agricultural Research (ACIAR) collaboration programme were used as susceptible check comparisons. Introgression lines derived from E. cardaminoides, D. tenuisiliqua and E. abyssinicum had much higher levels (P < 0.001) of resistance compared with the ACIAR germplasm. Median values of stem lesion length of introgression lines derived from the wild species were 1.2, 1.7 and 2.0 cm, respectively, as compared with the ACIAR germplasm where the median value for stem lesion length was 8.7 cm. This is the first report of high levels of resistance against S. sclerotiorum in introgression lines derived from E. cardaminoides, D. tenuisiliqua and E. abyssinicum. The novel sources of resistance identified in this study are a highly valuable resource that can be used in oilseed Brassica breeding programmes to enhance resistance in future B. napus and B. juncea cultivars against Sclerotinia stem rot.  相似文献   

20.
Toxicities of the eight quinones were evaluated through leaf dip bioassays conducted against Tetranychus urticae, Myzus persicae, Myzocallis walshii, and Illinoia liriodendri. Based on LC50 values, plumbagin (LC50 = 0.001%) was the most active compound against T. urticae and ubiquinone Q0 (LC50 = 0.005%), plumbagin (LC50 = 0.010%), and dibromothymoquinone (LC50 = 0.012%) were the most active compounds against M. persicae. The most active compounds against M. walshii were juglone (LC50 = 0.011%) and ubiquinone Q0 (LC50 = 0.019%), whereas dibromothymoquinone (LC50 = 0.030%), plumbagin (LC50 = 0.033%) and ubiquinone Q0 (LC50 = 0.058%) were the most toxic to I. liriodendri. Ecotrol (positive control) was the least toxic compound (LC50 = 0.39%) against T. urticae and M. persicae (LC50 = 0.447%). Although the majority of the compounds tested were toxic to all four test species in residual bioassays, there was little overlap among the test species in terms of susceptibility to the compounds and interspecific differences were observed. Regarding structure-activity relationships for quinones, the addition of a hydroxyl group resulted in a significant increase in the toxicity of the 1,4-naphthoquinones, and those possessing a methyl group exhibited the highest levels of activity in T. urticae. The bromine atom at the 2- and 5-positions of the benzoquinone ring is crucial to the toxicity of the compounds against I. liriodendri. Toxicity was greatly affected not only by the number of hydroxyl groups, but also by their positions in the ring in the case of M. walshii. Juglone and plumbagin as residual toxins in the laboratory also reduced the population of two-spotted spider mites compared to EcoTrol™ (positive control) and the negative control in the greenhouse experiment. Some quinones tested may have potential as commercial insecticides and miticides, or alternatively, could serve as lead compounds for the development of more potent crop protection agents.  相似文献   

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