Acaricidal active fractions from acetone extract of <Emphasis Type="Italic">Aloe vera</Emphasis> L. against <Emphasis Type="Italic">Tetranychus cinnabarinus</Emphasis> and <Emphasis Type="Italic">Panonychus citri</Emphasis>

This study aimed to isolate acaricidal active fractions from acetone extract of Aloe vera L. and investigate the toxicity of these fractions against Tetranychus cinnabarinus (T. cinnabarinus) and Panonychus citri (P. citri). Acetone extract of A. vera L. was isolated by immersing in acetone for 72 h, and diverse fractions were fractionated by column chromatography. The acaricidal activity of each fractions was evaluated by corrected mortality of T. cinnabarinus through slide-dip bioassay. The 8th and 13th fractions of acetone extract with good acaricidal activity were indentified by LC/MS, and the toxicity of these two fractions to T. cinnabarinus and P. citri was identified by regression analysis. Acetone extract of A. vera L. exhibited obvious acaricidal activity, from which a total of 18 fractions were isolated. The 8th and 13th fractions with strong acaricidal activity against T. cinnabarinus were identified to be 3-O-alpha-d-mannopyranosyl-d-mannopyranose (OAMM) and aloe emodin. When compared with spirodiclofen, both OAMM and aloe emodin exhibited higher toxicity to T. cinnabarinus, while only OAMM exhibited a higher toxicity to P. citri (P < 0.05). OAMM and aloe emodin isolated from acetone extract of A. vera L. exhibited obvious acaricidal activities against T. cinnabarinus and P. citri.     

Synthesis of matrinic amide derivatives containing 1,3,4-thiadiazole scaffold as insecticidal/acaricidal agents

In continuation of our program aimed at the development of natural product-based pesticidal agents, a series of matrinic amide derivatives containing 1,3,4-thiadiazole scaffold were prepared, and their insecticidal and acaricidal activities were evaluated against Mythimna separata and Tetranychus cinnabarinus. Some compounds exhibited potent insecticidal and acaricidal activities. It suggested that R¹ as a nitro group and R² as a fluorine atom, were important for the insecticidal activity; R¹ as the electron-donating groups and R² as the methyl group, were necessary for the acaricidal activity.     

Evaluation of insecticidal properties of botanicals for sustainable management of sucking pests of horticultural crops

Aphids, thrips, whiteflies, mealy bugs and mites could cause significant yield losses in horticultural crops. Many synthetic chemicals highly hazardous to non-target organisms and the environment are in use in their management. Botanicals are ideal for safe sustainable pest management by keeping synthetic chemical use at a minimum. We studied the insecticidal properties of three botanicals viz., Annona squamosa, Ricinus communis and Sapindus mukorossi seed extracts against sucking pests viz., aphids (Aphis gossypii and Aphis craccivora) on okra (Abelmoschus esculentus) and bittergourd (Momordica charantia), thrips (Scirtothrips dorsalis) on chilli (Capsicum frutescens), whiteflies (Bemisia tabaci) on eggplant (Solanum melongena), mealy bugs (Maconellicoccus hirsutus) on betel vine (Piper betle) and mites (Tetranychus urticae) on eggplant (Solanum melongena) under laboratory conditions. The bioassay showed that A. squamosa seed extract has potent insecticidal properties on all sucking pests, except T. urticae. Though S. mukorossi seed extract exhibited no insecticidal property, had a significant acaricidal property. A. squamosa and S. mukorossi seed extracts will therefore be additional botanicals for use in organic farming for managing the sucking pests effectively.     

Lethal activity of beauvericin,a Beauveria bassiana mycotoxin,against the two‐spotted spider mites,Tetranychus urticae Koch

The entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin is known to produce a broad range of secondary metabolites. Beauvericin, a cyclic hexadepsipeptide, is the best known mycotoxin produced by B. bassiana; however, reports discussing the insecticidal activity of beauvericin per se are limited. In this study, we assessed the lethal activity of beauvericin against Tetranychus urticae Koch (Acarina: Tetranychidae). In addition, screening for suitable application of the mycotoxin against T. urticae on greenhouse strawberries is discussed. Beauvericin was able to control successfully T. urticae where concentrations of 10, 100 and 1,000 µg/g recorded mortalities of 84%, 100% and 100%, respectively, against motile stages. Furthermore, beauvericin inhibited egg hatching up to 83.3%, 69.3% and 53.3%, respectively, using the same concentrations under laboratory conditions. Under greenhouse conditions, the efficacy recorded was 52.6%, 85.7%, 72.4% and 72.4% at 1, 3, 7 and 10 days post‐inoculation, respectively. Beauvericin was efficacious under greenhouse conditions since the application increased strawberry yields while showing no phytotoxicity and ecotoxicological risk. Resistance to beauvericin was not detected initially at the unselected strain of T. urticae. Yet, the laboratory selection of populations of T. urticae exposed to beauvericin resulted in relatively resistant T. urticae strain that displayed no cross‐resistance to cyflumetofen and bifenazate. The acaricidal activity of beauvericin documented in this study would increase the efficacy of integrated pest management strategies.     

Screening of insecticidal activity of plant essential oils and extract-based formulations against four agricultural insect pests and their risk assessment

Frankliniella occidentalis (Pergande), Myzus persicae (Sulzer), Plutella xylostella (L), and Spodoptera exigua (Hübner) are notorious agricultural insect pests worldwide. Due to the rapid development of resistance to the conventional insecticides, the number of available insecticides might be reduced in a near future, and botanical insecticides can be considered as one of the potential candidates to solve this problem. In the present study, test formulations were prepared using plant essential oils and extracts as main active ingredients, and their insecticidal activity and phytotoxicity were examined. Among the combinations tested, two oil-in-water formulations of NRS-13 containing thyme white oil and NRS-24 containing basil and rosemary oils were selected based on their notable insecticidal activity and low phytotoxicity. Chemical analyses on the active essential oils, the quantitative analysis of the major components in the formulations, insecticidal activities under pot and field conditions, their acute toxicity on mammals, and ecotoxicity on fish were also examined. The NRS-13 (BaechooSafer^TM) and NRS-24 (JindiOut^TM) formulations showed species-specific insecticidal activity against P. xylostella and M. persicae, respectively. In addition, both formulations produced low acute oral and dermal toxicity, skin and eye irritation, and fish toxicities, which suggests those formulations based on essential oils could be considered as insecticides for pest control in small-scale environments in organic farming.     

Multiple indole glucosinolates and myrosinases defend Arabidopsis against Tetranychus urticae herbivory

Arabidopsis (Arabidopsis thaliana) defenses against herbivores are regulated by the jasmonate (JA) hormonal signaling pathway, which leads to the production of a plethora of defense compounds. Arabidopsis defense compounds include tryptophan-derived metabolites, which limit Arabidopsis infestation by the generalist herbivore two-spotted spider mite, Tetranychus urticae. However, the phytochemicals responsible for Arabidopsis protection against T. urticae are unknown. Here, we used Arabidopsis mutants disrupted in the synthesis of tryptophan-derived secondary metabolites to identify phytochemicals involved in the defense against T. urticae. We show that of the three tryptophan-dependent pathways found in Arabidopsis, the indole glucosinolate (IG) pathway is necessary and sufficient to assure tryptophan-mediated defense against T. urticae. We demonstrate that all three IGs can limit T. urticae herbivory, but that they must be processed by myrosinases to hinder T. urticae oviposition. Putative IG breakdown products were detected in mite-infested leaves, suggesting in planta processing by myrosinases. Finally, we demonstrate that besides IGs, there are additional JA-regulated defenses that control T. urticae herbivory. Together, our results reveal the complexity of Arabidopsis defenses against T. urticae that rely on multiple IGs, specific myrosinases, and additional JA-dependent defenses.

Three IGs and specific myrosinases help protect Arabidopsis thaliana against herbivory by the two-spotted spider mite T. urticae.     

Development of Neoseiulus womersleyi (Schicha) and Euseius ovalis (Evans) feeding on four tetranychid mites (Acari: Phytoseiidae,Tetranychidae) and pollen

The development of the predatory mites, Neoseiulus womersleyi (Schicha) and Euseius ovalis (Evans), feeding on four tetranychid mites (Tetranychus urticae, Tetranychus kanzawai, Oligonychus mangiferus, Panonychus citri), maize pollen or Chinese loofah pollen was studied at 25 °C. Immature stages of N. womersleyi feeding on T. urticae and T. kanzawai had shorter developmental duration (4.71 and 5.02 days for females, 4.77 and 5.19 days for males, respectively) than those feeding on other food sources. Immature stages of E. ovalis females feeding on O. mangiferus and T. urticae developed in 4.99 and 5.13 days, respectively, the shortest developmental duration measured. Immature stages of E. ovalis males feeding on O. mangiferus and T. urticae developed in 5.12 and 5.37 days, respectively. The longevity of N. womersleyi males (13.31 to 14.51 days) and females (17.67 to 21.81 days) feeding on T. urticae, T. kanzawai or maize pollen was longer than the longevity of N. womersleyi feeding on O. mangiferus, P. citri or loofah pollen. E. ovalis males (12.91 to 16.74 days) and females (16.24 to 23.77 days) feeding on O. mangiferus, T. urticae or maize pollen lived longer than E. ovalis males and females feeding on T. kanzawai, P. citri or loofah pollen.     

Chemical Control System of Frankliniella occidentalis (Thysanoptera: Thripidae) in Greenhouse Eggplant

Systems of chemical control were implemented in a plastic greenhouse to control mainly Frankliniella occidentalis (Pergande) in eggplant with several effective eligible groups of insecticides, spraying insecticide singly with new mode of action or in sequence with conventional. The system consisted of three phase of strategy to cope with initial population build up, sporadic pests and F. occidentalis population control. To check the effectiveness of the control system it was evaluated phytotoxicity, the residual toxicity, spraying frequency, insecticidal spectrum against Tetranychus urticae Koch, and Liriomyza trifolii (Burgess), and marketable quality and yield. Spraying singly with abamectin or imidacloprid gave high yields with low damage to the eggfruits. Furthermore abamectin 1.8 emulsifiable concentrate (Ec) showed wide range of insecticidal activity against T. urticae and L. trifolii with slightly less spraying frequency.     

Synthesis of novel quinolinomatrine derivatives and their insecticidal/acaricidal activities

In continuation of our program to discover natural product-based pesticidal agents, a series of new quinolinomatrine derivatives were prepared. Especially three-dimensional structures of five compounds were unambiguously determined by single-crystal X-ray diffraction. Among them, 21-chloroquinolinomatrine exhibited good insecticidal and acaricidal activities against two crop-threatening insect pests, Mythimna separata and Tetranychus cinnabarinus. Their structure-activity relationships were also discussed.     

Integrated control of two spotted spider mite,Tetranychus urticae on cucumber grown under plastichouse conditions in egypt

Microclimatic conditions were monitored in cucumber grown under unheated plastichouses in three consecutive years, i.e. from 1990 to 1992 in Egypt. The relative humidity in the plastichouses constructed on either sandy or clay soil did not exceed 30% during mid-day time, while the average temperature did not drop below 30°C. Such conditions favoured population build up of the two spotted spider miteTetranychus urticae Koch. In 1993 and 1994, three plastichouses planted to cucumber, cultivar Rawa or Hana were selected. Relative humidity in two of them was maintained over 50% during the day using spraying nozzles, the third being kept as control. Mildew diseases induced by increased leaf wetness needed to be managed using fungicides.Phyioseiulus persimilis andP. longipes were released in the first two plastichouses, while acaricides were applied in the control. In early MayT. urticae population increase on the growing top of cucumber plants required two acaricidal applications as predatory mites did not migrate to the apical leaves which were too warm and dry. More than 80% of the maximum yield was obtained on average in plastichouses using increased relative humidity, but without any acaricidal applications.     

Acaricidal potential of some essential oils and their monoterpenoids against the two-spotted spider mite Tetranychus urticae (Koch.)

Abstract

The acaricidal potential of fourteen essential oils and fourteen of their major monoterpenoids were tested against the Two-spotted spider mite Tetranychus urticae. Two different time intervals of 24 and 48 hrs were used in evaluation. The assays after 24 hrs showed that mattercary, fennel, caraway, garlic, cinnamon, chenopodium and eucalyptus were highly potent. As for monoterpenoids, chlorothymol was found to be the most effective against T. urticae followed by thymol, carvacrol and cinnamaldehyde.     

Indoloditerpenes from an algicolous isolate of Aspergillus oryzae

Two new indoloditerpene derivatives asporyzin A (1) and asporyzin B (2), one new indoloditerpene asporyzin C (3), and three known related indoloditerpenes JBIR-03 (4), emindole SB (5), and emeniveol (6) were isolated from an endophytic fungus Aspergillus oryzae, isolated from the marine red alga Heterosiphonia japonica. Their structures were unambiguously established by spectroscopic techniques. In addition, all the isolates were evaluated preliminarily for insecticidal and antimicrobial activities in order to probe into their chemical defensive function. Compound 4 was more active against brine shrimp than the others, and 3 possessed potent activity against Escherichia coli.     

Acaricidal and repellent effects of myrtacean essential oils and their major constituents against Tetranychus urticae (Tetranychidae)

Nineteen plant essential oils (EOs) extracted from the family Myrtaceae growing in Australia were screened for their acaricidal and repellent activities against two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), in the laboratory by dipping method and choice- and no-choice tests. Acaricidal bioassays showed that five EOs of Callistemon viminalis, Eucalyptus bicostata, Eucalyptus maidenii, Eucalyptus sideroxylm and Eucalyptus approximans significantly increased the mortality of female adult mites and decreased the total number of eggs. In a choice test, Callistemon sieberi, E. bicostata, Eucalyptus ovata, E. sideroxylm, Eucalyptus mannifera, Eucalyptus dives, Eucalyptus elata, Eucalyptus condonocarpa, Kunzea ericoides, Melaleuca armillaris and Melaleuca fulgens demonstrated good repellency to the mite. In another test, C. sieberi, E. bicostata, E. mannifera, E. condonocarpa, K. ericoides, M. armillaris, and M. fulgens EOs decreased the egg production of the females significantly. In the acaricidal and repellent tests, E. bicostata and E. sideroxylon EOs showed both acaricidal and repellent effects (choice test) and decreased the number of eggs on treated bean leaves. The gas chromatograph/mass spectroscopy analyses revealed that the major components of E. bicostata and E. sideroxylon were 1,8-cineole, limonene, and α-pinene. The 1,8-cineole and limonene showed significant repellent effects on the mites, resulting in reduced numbers of eggs in the choice test. Hence, EOs of E. bicostata and E. sideroxylon and limonene and 1,8-cineole may be potential agents to be used in the sustainable management of T. urticae.     

Coincidental intraguild predation by caterpillars on spider mites

Intraguild predation (IGP) is defined as the killing and eating of prey species by a predator that also can utilize the resources of the prey. It is mainly reported among carnivores that share common herbivorous prey. However, a large chewing herbivore could prey upon sedentary and/or micro herbivores in addition to utilizing a host plant. To investigate such coincidental IGP, we observed the behavioral responses of the polyphagous mite Tetranychus kanzawai Kishida (Acari: Tetranychidae) when its host plant Cayratia japonica (Thunb.) Gagnep. (Vitaceae) was attacked by hornworms, Theretra japonica Boisduval (Sphingidae) and T. oldenlandiae Fabricius (Sphingidae). We also examined an interaction between the oligophagous mite Panonychus citri McGregor (Acari: Tetranychidae) and caterpillars of the swallowtail Papilio xuthus L. (Papilionidae) that share citrus plants as their main food source. Although all T. kanzawai and some active stage P. citri tried to escape from the coincidental IGP, some were consumed together with eggs, quiescent mites, and host plant leaves, suggesting that coincidental IGP occurs on spider mites in the wild. Moreover, neither hornworms nor swallowtail caterpillars distinguished between spider mite-infested and uninfested leaves, suggesting that the mite-infested leaves do not discourage caterpillar feeding. The reasons that the mites have no effective defense against coincidental IGP other than escaping are discussed.     

Antioxidant and Antimicrobial Activity in Some Indian Herbal Plants: Protective Effect against Free Radical Mediated DNA Damage

Indian herbal plant species Lantana indica, Adhatoda vasica, Pandanus furcatus, Tylophora indica and Centella asiatica, traditionally used in ethno medicines to treat common infections and various disorders, have been studied for their antimicrobial and antioxidant activity. The methanolic extracts of the plant leaves exhibited significant and dose-dependent antioxidant activities in DPPH radical scavenging, ferric ion reducing and phosphomolybdate assays. These leaf extracts showed antimicrobial activity against selected Gram +ve and Gram ?ve bacterial strains. A. vasica and L. indica extracts possessed maximum antioxidant and antimicrobial activity, respectively. The activities could be correlated to phenolics and flavonoid content of the leaf extracts which ranged from 30.25 to 91.98 mg GAE g^?1 dw leaf extract and 2.67 to 96.45 mg RE g^?1 dw leaf extract respectively. The aqueous extracts of plant leaves significantly protected the DNA damage against the oxidative damage caused by hydroxyl radicals.     

牛蒡L1-2组分对桔全爪螨的毒性和几种代谢酶的作用

【目的】探讨杀螨植物牛蒡Arctium lappa L.提取物中主要杀螨成分L1-2的杀螨作用机理。【方法】采用叶片浸渍法处理桔全爪螨Panonychus citri雌成螨后,测定了静止期、兴奋期、痉挛期、麻痹期、复苏和死亡期5个中毒阶段试虫体内几种代谢酶的活性。【结果】L1-2组分在静止期和复苏期对羧酸酯酶（carboxylesterase, CarE）具有一定的抑制作用,在其他时期均激活CarE活性。除了静止期外,在其他时期均能激活乙酰胆碱酯酶（acetylcholinesterase , AChE）和谷胱甘肽转移酶（glutathione S-transferases, GSTs）的活性,在痉挛期和麻痹期活性增强,随后在麻痹期和复苏期降低。【结论】L1-2组分对CarE的抑制与其毒杀活性有关,而中毒试虫的复苏可能与AChE和GSTs有关。该组分可在较长时期内影响桔全爪螨的神经传导及消化和生殖系统,具有潜在的应用研究价值。     

Acaricidal property of the essential oil from <Emphasis Type="Italic">Lippia gracilis</Emphasis> against <Emphasis Type="Italic">Tetranychus urticae</Emphasis> and a natural enemy, <Emphasis Type="Italic">Neoseiulus californicus</Emphasis>, under greenhouse conditions

The essential oil from the leaves of Lippia gracilis was investigated for fumigant and residual activity against Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae). The results were compared to eugenol, Ortus^® and Azamax^®, as positive controls. Gas chromatography (GC) and GC/mass spectrometry analysis enabled the identification of 28 compounds, accounting for 99.1?±?0.6% of the essential oil. The major constituents were carvacrol (61%), p-cymene (11%) and thymol (11%). Mites were more susceptible to the oil in fumigant tests than in residual tests. Among the components, thymol and β-caryophyllene had the greatest fumigant and residual toxicity against T. urticae, respectively. The role of selected constituents (carvacrol, p-cymene, thymol, limonene, β-pinene, 1,8-cineole, terpinolene and β-caryophyllene) in the acaricidal properties of the L. gracilis essential oil is also discussed. Fumigant and residual effects of Lippia oil were more selective than eugenol with regard to a natural enemy of T. urticae, Neoseiulus californicus. Experiments under greenhouse conditions demonstrated greater toxicity of the Lippia oil in comparison to the positive control at 24, 48 and 72 h after treatment. The results suggest that Lippia oil is a good candidate for the formulation of a botanical acaricide for the integrated management of T. urticae.     

栀子八氢番茄红素合成酶基因的分离及表达分析

为探讨栀子(Gardenia jasminoides)果实中藏花素的合成机理,克隆了栀子类胡萝卜素生物合成的关键酶八氢番茄红素合成酶(GjPSY)基因的全长cDNA。结果表明,推导的GjPSY氨基酸序列与双子叶植物来源的GjPSY亲缘关系较近。采用HPLC检测栀子果实中的藏花素-1含量为(3.96±1.48) mg g-1,在叶片中未检出。通过RT-PCR分析表明,GjPSY在栀子叶片和果实中均有表达,且表达水平一致。因此推测,GjPSY的转录水平与果实中藏花素-1的合成无关。     

The presence of webbing affects the oviposition rate of two-spotted spider mites, <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Tetranychidae)

Several species of tetranychid mites including Tetranychus urticae Koch (Acari: Tetranychidae) construct complicated three-dimensional webs on plant leaves. These webs provide protection against biotic and abiotic stress. As producing web is likely to entail a cost, mites that arrive on a leaf with web are expected to refrain from producing it, because they will gain the benefit of protection from the existing web. Mites that produce less web may then allocate resources that are not spent on web construction to other fitness-enhancing activities, such as laying eggs. To test this, the oviposition rate of T. urticae adult females was examined on leaves with web. As a control, we used leaves where the web had been removed, hence both types of leaves had been exposed to conspecifics previously and were thus damaged. On leaves with web, the oviposition rate of T. urticae females was higher than on leaves where the web had been removed. Therefore, the presence of web constructed by conspecifics enhanced the oviposition rate of T. urticae females. This provides indirect evidence that mites use the web constructed by conspecifics and thereby save resources that can be allocated to other traits that enhance reproductive success.     

Insecticidal and Acaricidal Activity of Certain O,O-Dialkyl O-3-Pyridazinyl Phosphorothioates

Forty-three 3-pyridazinyl phosphorothioates were evaluated for insecticidal and acaricidal activities against two-spotted spider mite, turnip aphid, smaller brown planthopper, mosquito larvae and American cockroach. Approximate acute oral toxicity of these compounds in mice was also examined. In general, the toxicity in mice was in parallel with the pesticidal activity, but a few compounds clearly showed a high degree of selectivity between pests and mice. Especially O,O-dimethyl O-(6-cyclohexyloxy-3-pyridazinyl)phosphorothioate showed substantially reduced mammalian toxicity but maintained high insecticidal and acaricidal activity.