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1.
BACKGROUND: Tropical plants are recognised sources of bioactive compounds that can be used for pest control. The objective of this study was to evaluate the biological activity of compounds present in Acmella oleracea (Asteracea) against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), which is the main pest of tomato crops in Latin America. The selectivity of these compounds to the predator Solenopsis saevissima (Smith) (Hymenoptera: Formicidae) and to the pollinator Tetragonisca angustula (Latr.) (Hymenoptera: Apidae: Meliponinae) was also of interest. RESULTS: A bioassay screening with hexane and ethanol extracts from 23 plants was performed. The hexane extract of A. oleraceae was the most active of the extracts and was selected for further study. The following three alkamides were isolated from a hexane extract of the aerial parts of A. oleracea : spilanthol, (E)‐N‐isobutylundeca‐2‐en‐8,10‐diynamide and (R, E)‐N‐(2‐methylbutyl)undeca‐2‐en‐8,10‐diynamide. All of the isolated compounds showed insecticidal activity, with spilanthol being the most active (LD50 = 0.13 µg mg?1) against T. absoluta . The alkamides were selective to both beneficial species studied. CONCLUSION: The crude hexane extract of A. oleraceae showed high insecticidal activity and can be used to control T. absoluta in organic or conventional crops. Quantification of LD50 values of isolated compounds against T. absoluta showed that alkamides could serve as potent insecticides for T. absoluta control programmes. Spilanthol was the main alkamide active isolated. This alkamide is the most promising as it has the highest insecticidal activity and is selective to non‐target organisms. Copyright © 2011 Society of Chemical Industry  相似文献   

2.
The influence of different combinations of illumination and shaking on the growth dynamics, pathogenicity and toxin production of the fungus Fusarium oxysporum f. sp. orthoceras, a biocontrol agent of Orobanche cumana, was studied. The fastest biomass accumulation was obtained under shaking, with or without illumination, with the highest biomass obtained after 3–4 weeks of growth. The biological activity of chloroform extracts of the culture filtrate was characterised: it contained at least two main toxic metabolites that caused necrosis and wilting of various plants and led to mortality of germinating seeds of O. cernua, O. aegyptiaca, O. ramosa and O. cumana. The highest toxic activity of the chloroform extract was obtained under illumination without shaking after 3–4 weeks of growth. The two toxic metabolites were purified and identified as fusaric acid (FA) and 9,10‐dehydrofusaric acid (DFA). Both FA and DFA production began in the first week of growth, increasing gradually to their maxima after 4 weeks. The highest level of pathogenic activity of the fungus was obtained after three or more weeks of fungal growth. It can be concluded that in order to produce high levels of toxin and pathogenic activity, the fungus should be grown under illumination without shaking for 4 weeks.  相似文献   

3.
Hexadeuterio-lindane(γ-BHC-d6) was several times as toxic as lindane against the mosquito (Culex pipiens pallens), house fly (Musca domestica), German cockroach (Blattella germanica) and American cockroach (Periplaneta americana). The neuroexcitatory activity of these two compounds did not differ. Lindane was considerably synergized by piperonyl butoxide, but lindane-d6 was not. A large isotope effect was observed in the in vivo breakdown of lindane-d6. Thus, the intrinsic toxicities of both compounds are equivalent. The difference in insecticidal activity seems to be due to the different rates of detoxifying biodegradation caused by the kinetic deuterium isotope effect.  相似文献   

4.
MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP+ (1-methyl-4-phenylpyridinium ion) are potent dopaminergic neurotoxins in mammals. The mammalian toxicity of MPTP depends on its conversion, by monoamine oxidase, to MPP+. MPTP is toxic to cockroaches (LD50 720 μg gm?1) and the results suggest that MPTP toxicity depends on monoamine oxidase activity at a site outside the nervous system. MPTP depletes dopamine from cockroach cerebral ganglia and MPP+ inhibits cockroach mitochondrial respiration. While the biochemistry of MPTP toxicity appears to be the same as in mammals it seems that insects are unable to detoxify MPTP before its action has fatal consequences outside the nervous system.  相似文献   

5.
The pest control potential demonstrated by various extracts and compounds isolated from the kernels and leaves of the neem plant (Azadirachta indica) A. Juss. (Meliaceae) seem to be of tremendous importance for agriculture in developing countries. Laboratory and field trial data have revealed that neem extracts are toxic to over 400 species of insect pests some of which have developed resistance to conventional pesticides, e.g. sweet potato whitefly (Bemisia tabaci Genn. Diptera: Aleyrodidae), the diamond back moth (Plutella xylostella L. Lepidoptera: Plutellidae) and cattle ticks (Amblyomma cajennense F. Acarina: Ixodidae andBoophilus microplus Canestrini. Acarina: Ixodidae). The compounds isolated from the neem plant manifest their effects on the test organisms in many ways, e.g. as antifeedants, growth regulators, repellents, toxicants and chemosterilants. This review strives to assess critically the pest control potential of neem extracts and compounds for their use in the tropics. This assessment is based on the information available on the wide range of pests against which neem extracts and compounds have proven to be toxic, toxicity to non-target organisms, e.g. parasitoids, pollinators, mammals and fish, formulations, stability and phytotoxicity.  相似文献   

6.
Substitution of silicon for carbon was explored in etofenprox and MTI-800, primarily to establish the suitability of silicon for pesticide construction and to probe steric effects. It was shown that silicon is an effective building block for insecticides with subtle qualitative and quantitative differences relative to the carbon analogs. The silanes were slightly less toxic to insects than the carbon analogs (relative potency of 0.2-0.6) but the silane analog of MTI-800 was considerably less toxic to fish (0% mortality at ≥50 mg liter?1) than MTI-800 itself (LC50 = 3 mg liter?1). The mode of action of both carbon and silicon compounds was similar in the intact, electrode-implanted cockroach and involved repetitive firing of a sensory nerve; potency measurements were also made using an in-vitro nerve assay. The possible metabolic and physicochemical contributions to the observed insecticide potencies were explored using synergism studies, physical chemistry measurements and quantum mechanical calculations.  相似文献   

7.
Annona squamosa L. is widespread in Sri Lanka and its leaves are collected by some farmers to protect their stored cowpeas from predation by bruchids. Removal of the leaves during the dry season, when the fanners harvest their cowpeas, can decrease the yield ofA. squamosa fruit. This study investigated whether storing the leaves before they are used would reduce the insecticidal activity of the leaves. Overall, acetone and ethanol extracts made from fresh and stored leaves ofA. squamosa decreased the number of adultCallosobruchus maculatus (F.) emerging from cowpeas; however, in some bioassays the extracts from fresh leaves were more active than those from leaves stored for 6 months. Acetone extracts from fresh and stored leaves were toxic to adult beetles, whereas the ethanol extracts were not active. Acetone and ethanol extracts from fresh leaves had potent ovicidal activity when applied to 2-day-old eggs.  相似文献   

8.
苦瓜活性组分物质抑菌活性测定   总被引：2，自引：0，他引：2  
以苦瓜(Momordica charantia L.)种仁中提取的凝集素备提物和苦瓜籽粗蛋白对8种植物病原真菌,5种植物病原细菌进行了抑菌活性测定。结果表明:两种提取物对小麦赤霉病菌、棉花黄萎病菌和苹果炭疽病菌表现出较好的抑菌活性。凝集素备提物(0.67 mg/mL)对小麦赤霉病菌和棉花黄萎病菌的抑菌率分别为69.12%和64.86%;苦瓜籽粗蛋白(6.67 mg/mL)对苹果炭疽病菌的抑菌率达68.61%。两种提取物对大白菜软腐病菌、花生青枯病菌、水稻白叶枯病菌和根癌农杆病菌等植物病原细菌均无抑菌活性,苦瓜籽粗蛋白(0.1 g/mL)对水稻细条病菌有一定抑制作用。  相似文献   

9.
BACKGROUND: Leaf‐cutting ants are considered to be one of the most important pest species of the New World. Until now, control strategies against these leaf‐cutting ants have mainly been synthetic chemicals. The aim of the present study was to test the action of several plant extracts quoted as an example by TRAMIL participative surveys for their insecticidal properties on adult major workers of Acromyrmex octospinosus. Three tests were used to that end: contact toxicity, repellent test and ingestion bioassay. Six traditional plant uses recommended by interviewed people in surveys were tested: (1) maceration of Mammea americana fresh crushed seeds; (2) decoction of Nerium oleander fresh leaves; (3) Nerium oleander dried leaf water juice; (4) decoction of Nicotiana tabacum dried leaves; (5) Trichillia pallida dried leaf water juice; (6) decoction of Rollinia mucosa dried seeds. RESULTS: Two plant extracts with contact toxicity (Mammea americana and Nicotiana tabacum), six plant extracts with repellent activity and four plant extracts with ingestion toxicity (Mammea americana, Nicotiana tabacum and both extracts of Nerium oleander) were found. CONCLUSION: The data presented in this study showed that plant extracts cited by TRAMIL ethnopharmacological surveys have the potential to control the leaf‐cutting ant, Acromyrmex octospinosus. In particular, the Mammea americana extract, with its natural low repellent effect and its high toxicity by ingestion, and Nerium oleander extracts, with their natural delay action, are possibly the best extracts for the control of these ants. Copyright © 2011 Society of Chemical Industry  相似文献   

10.
In Germany, the dusky cockroach (Ectobius lapponicus [Linné, 1758]) lives in woodland. Dwelling of these insects which are not considered a pest, in buildings is an extremely rare observation. In early summer of 2000, several areas of a forest hospital were found to be infested withEctobius lapponicus. In contrast, the German cockroach (Blattella germanica [Linné, 1767]) had not been found in that, hospital for years. In the light of the literature available, an attempt is made to provide a survey of infestation of buildings with the dusky cockroach.   相似文献   

11.
Evidence of the brown-banded cockroach (Supella longipalpa [Fabricius, 1798]) in Saxony-Anhalt In the past, evidence of the brown-banded cockroach in the Land of Saxony-Anhalt was based on reports furnished by pest control businesses to the extent that brown-banded cockroaches had been traced on the premises of two Magdeburg companies in 1985. A specimen of brown-banded cockroach was recently detected in the Land of Saxony-Anhalt (March 2000). The roach was found in the office of a smallsized business in the town of Wolmirstedt north of Magde burg. The route along which the pest had entered the premises, or been brought in, could not be elucidated.   相似文献   

12.
Abstract

Different solvent extracts of neem seed kernels were evaluated against Spodoptera litura F. on cauliflower, Brassica oleracea var. botrytis leaves. Based on this evaluation, aqueous extract was dissolved in ethanol, and methanol extract in ethanol, and dissolved parts were designated as fraction I and fraction II, respectively. The extracts having more antifeedant activity were encapsulated to achieve stability against the sunlight. Among the solvent extracts tested at 1.0% concentration, methanol extract provided maximum protection (100%) of the leaves followed by ethanol (98.39%) and aqueous (93.01%) extracts. Fraction I and fraction 11 were equally effective at 0.1 % concentration against S. litura larvae and checked more than 70% of leaf damage. However, such extracts were found to be unstable when exposed to sunlight. The pre‐gelatinized starch‐encapsulated products, viz. ρre‐gel I and pre‐gel II were quite stable and afforded more than 68.0% protection to the cauliflower leaves even after 6 days of exposure to sunlight.  相似文献   

13.
BACKROUND: In the present study, the effect of thiamethoxam and clothianidin on the locomotor activity of American cockroach, Periplaneta americana (L.), was evaluated. Because it has been proposed that thiamethoxam is metabolised to clothianidin, high‐performance liquid chromatography coupled with mass spectrometry was used to evaluate the amount of clothianidin on thiamethoxam‐treated cockroaches. RESULTS: One hour after neonicotinoid treatment, the time spent in the open‐field‐like apparatus significantly increased, suggesting a decrease in locomotor activity. The percentage of cockroaches displaying locomotor activity was significantly reduced 1 h after haemolymph application of 1 nmol g?1 neonicotinoid, while no significant effect was found after topical and oral administration. However, at 24 and 48 h, all neonicotinoids were able to reduce locomotor activity, depending on their concentrations and the way they were applied. Interestingly, it was found that thiamethoxam was converted to clothianidin 1 h after application, but the amount of clothianidin did not rise proportionately to thiamethoxam, especially after oral administration. CONCLUSION: The data suggest that the effect of thiamethoxam on cockroach locomotor activity is due in part to clothianidin action because (1) thiamethoxam levels remained persistent 48 h after application and (2) the amount of clothianidin in cockroach tissues was consistent with the toxicity of thiamethoxam. Copyright © 2010 Society of Chemical Industry  相似文献   

14.
In Germany, the dusky cockroach (Ectobius lapponicus [Linné, 1758]) lives in woodland. Dwelling of these insects which are not considered a pest, in buildings is an extremely rare observation. In early summer of 2000, several areas of a forest hospital were found to be infested withEctobius lapponicus. In contrast, the German cockroach (Blattella germanica [Linné, 1767]) had not been found in that, hospital for years. In the light of the literature available, an attempt is made to provide a survey of infestation of buildings with the dusky cockroach.  相似文献   

15.
Nawaz  Asma  Hussain  Zahid  Akhtar  Naveed  Hussain  Fida  Ullah  Naeem 《Gesunde Pflanzen》2022,74(2):477-486

Soliva sessilis (Burweed) is a winter annual weed found in wheat crop of Pakistan. It is thought to have an allelopathic effect on wheat crop. In this regard, an experiment was conducted in 2019 in the department of Weed Science and Botany at the University of Agriculture Peshawar, to assess the allelopathic potential of S. sessilis on various wheat varieties grown in Peshawar, Pakistan. Physiologically matured roots and leaves of S. sessilis were dried, ground and stored. Three common wheat varieties were selected for the research including Atta Habib, Pirsabaq-15, and Shahkar-13. The treatments of the experiment comprised of the aqueous extracts of the roots and leaves of S. sessilis, hot water extracts, methanol extracts, litter, and mulches. A mass of 5?g of S. sessilis was taken for the different extracts for 24?h, however, the methanol extract was kept for 48?h. The effect of the treatments was highly significant on wheat seed germination, radicle length, plumule length, fresh biomass as well as dry biomasses of the three tested wheat varieties. The variety Atta Habib was discovered as the most susceptible variety to the treatments of aqueous extracts, hot water extracts, and leaves’ litter. In contrary, the variety Pirsabaq-15 exhibited a remarkable increase in the various data collection parameters. The leaves of S. sessilis were observed more toxic as compared to the roots. The mulch of S. sessilis indicated stimulatory effect on the wheat varieties. For the interaction effect between treatments and varieties, the leaves and roots aqueous extract and their litter showed inhibitory effect. In conclusion, the leaves and roots of S. sessilis are potentiality allelopathic to wheat crop plants and further study is needed to assess the types of these allelochemicals present in the leaves and roots of the weed.

  相似文献   

16.
The numbers of diseased plants could significantly be reduced when microconidia ofFusarium oxysporum f. sp.dianthi were inoculated into the stem and viable-, heat-killed cells or purified LPS of the bacteriumPseudomonas sp. strain WCS417r were applied to the roots. Because the competition betweenF. o. dianthi and the bacterium could be excluded, the disease suppression seems to be due to an induced resistance. Accumulation of phytoalexins was found in the stem segments. No accumulation of these compounds was found when the plants were bacterized but noninfected. It is concluded that cell surface components present in the lipopolysaccharides of the bacterium are the inducing factors.Increased peroxidase activity could be measured in root washes and root extracts after only bacterial preparations were added. No significant differences in peroxidase activity were found in stem extracts. The possible role of increased peroxidase activity in suppression of Fusarium wilt in carnation is discussed.  相似文献   

17.
Evidence of the brown-banded cockroach (Supella longipalpa [Fabricius, 1798]) in Saxony-Anhalt In the past, evidence of the brown-banded cockroach in the Land of Saxony-Anhalt was based on reports furnished by pest control businesses to the extent that brown-banded cockroaches had been traced on the premises of two Magdeburg companies in 1985. A specimen of brown-banded cockroach was recently detected in the Land of Saxony-Anhalt (March 2000). The roach was found in the office of a smallsized business in the town of Wolmirstedt north of Magde burg. The route along which the pest had entered the premises, or been brought in, could not be elucidated.  相似文献   

18.
The production of phytotoxins byFusarium oxysporum f.sp.lilii, a pathogen causing bulb and scale rot in lilies, was investigated. To determine the toxic activity of culture filtrate, a bioassay with in vitro grown scale bulblets or with callus was set up. The fungus produces toxic components in different culture media. The highest toxicity was observed in Czapek Dox medium. HPLC and GC/MS analyses revealed the presence of fusaric acid at toxic concentrations in this medium. The production of fusaric acid in time coincides with the increase of toxic activity in the culture filtrate. It is concluded that at least part of this toxicity is due to fusaric acid.  相似文献   

19.
Oral toxicity of boric acid, an inorganic insecticide, was evaluated on German cockroach, Blattella germanica L. (Dictyoptera, Blattellidae). Newly emerged adults were exposed to various concentrations of boric acid incorporated into the diet. Results showed that treated insects exhibited toxic symptoms with a dose-dependent mortality. Histological study of midgut revealed alterations in the epithelial cells and a significant increase in the epithelium thickness. In a second series of experiments, the compound was investigated on the activities of acetylcholinesterase (AChE) and glutathione S-transferases (GSTs). Data showed that the compound induced GSTs and reduced the activity of AChE. From this experiment, it may be concluded that ingested boric acid caused death of insects perhaps ultimately by starvation via alterations of the midgut. Additionally, the compound seemed to present a neurotoxic action as evidenced by the symptoms of poisoning and the reduction in AchE activity.  相似文献   

20.
The allelopathic potential of Mikania micrantha H.B.K. to affect the seed germination and seedling growth of Coix lacryma‐jobi L. was investigated. Water‐soluble allelopathic substances were found in the water extracts of M. micrantha. The effect of the water extracts on the seed germination and seedling growth of C. lacryma‐jobi was concentration‐dependent. The water extracts from the different plant parts (leaf, stem, and root) of M. micrantha differed in their effect on the germination and seedling growth of C. lacryma‐jobi, with the effect of the leaf extract being the least inhibitory. The malondialdehyde (MDA) content in the C. lacryma‐jobi seedlings increased by 64%, 45%, and 52% of the control with increasing concentrations of the extracts of the root, stem, and leaf (80, 400, and 400 g L?1, respectively). The extract from the M. micrantha roots significantly increased the catalase (CAT) activity of the C. lacryma‐jobi seedlings (48% and 54% of the control at the concentrations of 20 g L?1 and 80 g L?1, respectively). The extracts from the leaves and stems at low concentrations increased the CAT activity, but at high concentrations, the extracts decreased the CAT activity. The extracts from the roots, stems, and leaves at concentrations of 80, 400, and 400 g L?1 also significantly decreased the peroxidase (POD) activity of the C. lacryma‐jobi seedlings to 27%, 52%, and 34% of the control, respectively. These results indicate that the water extracts of M. micrantha could inhibit the seed germination and seedling growth of C. lacryma‐jobi through the regulation of anti‐oxidase activity, such as POD and CAT in the cells. The growth inhibition of the C. lacryma‐jobi seedlings is probably related to injury after oxidization of the cell membranes with the increase of MDA content.  相似文献   

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