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Insect Bioassay

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https://www.readbyqxmd.com/read/28081289/transgenic-cotton-expressing-cry10aa-toxin-confers-high-resistance-to-the-cotton-boll-weevil
#1
Thuanne Pires Ribeiro, Fabricio Barbosa Monteiro Arraes, Isabela Tristan Lourenço-Tessutti, Marilia Santos Silva, Maria Eugênia Lisei-de-Sá, Wagner Alexandre Lucena, Leonardo Lima Pepino Macedo, Janaina Nascimento Lima, Regina Maria Santos Amorim, Sinara Artico, Márcio Alves-Ferreira, Maria Cristina Mattar Silva, Maria Fatima Grossi-de-Sa
Genetically modified (GM) cotton events that effectively control cotton boll weevil (CBW), which is the most destructive cotton insect pest in South America, are reported here for the first time. This work presents the successful development of new GM cotton with high resistance to CBW conferred by Cry10Aa toxin, a protein encoded by entomopathogenic Bacillus thuringiensis (Bt) gene. The plant transformation vector harbouring cry10Aa gene driven by the cotton ubiquitination-related promoter uceA1.7 was introduced into a Brazilian cotton cultivar by biolistic transformation...
January 12, 2017: Plant Biotechnology Journal
https://www.readbyqxmd.com/read/28062794/larvicidal-and-growth-inhibitory-activity-of-entomopathogenic-bacteria-culture-fluids-against-aedes-aegypti-diptera-culicidae
#2
João Luiz Rosa da Silva, Fernanda Undurraga Schwalm, Carlos Eugênio Silva, Marisa da Costa, Ralf Heermann, Onilda Santos da Silva
Dengue, Chikungunya, and Zika are important vector-borne diseases, and Aedes aegypti L. is their main transmitter. As the disease management is mainly based on mosquito control strategies, the search for alternative and cost-effective approaches is ongoing. The Gram-negative bacteria Xenorhabdus nematophila and Photorhabdus luminescens are symbiotically associated with entomopathogenic nematodes and are highly pathogenic for insect larvae. After we have recently confirmed the toxicity of these bacteria in Ae...
January 6, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28060922/cry3bb1-resistant-western-corn-rootworm-diabrotica-virgifera-virgifera-leconte-does-not-exhibit-cross-resistance-to-dvsnf7-dsrna
#3
William Moar, Chitvan Khajuria, Michael Pleau, Oliver Ilagan, Mao Chen, Changjian Jiang, Paula Price, Brian McNulty, Thomas Clark, Graham Head
BACKGROUND AND METHODOLOGY: There is a continuing need to express new insect control compounds in transgenic maize against western corn rootworm, Diabrotica virgifera virgifera (LeConte) (WCR). In this study three experiments were conducted to determine cross-resistance between the new insecticidal DvSnf7 dsRNA, and Bacillus thuringiensis (Bt) Cry3Bb1; used to control WCR since 2003, with field-evolved resistance being reported. Laboratory susceptible and Cry3Bb1-resistant WCR were evaluated against DvSnf7 dsRNA in larval diet-incorporation bioassays...
2017: PloS One
https://www.readbyqxmd.com/read/28050633/biopolymer-microencapsulations-of-bacillus-thuringiensis-crystal-preparations-for-increased-stability-and-resistance-to-environmental-stress
#4
Xiaolin He, Zhongqin Sun, Kanglai He, Shuyuan Guo
Parasporal crystals synthesized by Bacillus thuringiensis (Bt) have been widely used as microbial pesticides because of their toxicity to the larval stages of specific insects. However, parasporal crystals can be damaged by environmental stresses, such as high temperature, ultraviolet radiation, and desiccation. To reduce environmental susceptibility of parasporal crystals and extend the duration of their activity, we developed a new type of protection by making microcapsules of crystals (MCs). The microcapsules were self-assembled by alternate deposition (layer by layer) of low-cost chitosan and sodium alginate (or sodium carboxymethyl cellulose) on the crystal surface...
January 3, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28045942/knock-down-of-whitefly-gut-gene-expression-and-mortality-by-orally-delivered-gut-gene-specific-dsrnas
#5
Meenal Vyas, Amir Raza, Muhammad Yousaf Ali, Muhammad Aleem Ashraf, Shahid Mansoor, Ahmad Ali Shahid, Judith K Brown
Control of the whitefly Bemisia tabaci (Genn.) agricultural pest and plant virus vector relies on the use of chemical insecticides. RNA-interference (RNAi) is a homology-dependent innate immune response in eukaryotes, including insects, which results in degradation of the corresponding transcript following its recognition by a double-stranded RNA (dsRNA) that shares 100% sequence homology. In this study, six whitefly 'gut' genes were selected from an in silico-annotated transcriptome library constructed from the whitefly alimentary canal or 'gut' of the B biotype of B...
2017: PloS One
https://www.readbyqxmd.com/read/28045087/nutrition-affects-insect-susceptibility-to-bt-toxins
#6
Carrie A Deans, Spencer T Behmer, Ashley E Tessnow, Patricia Tamez-Guerra, Marianne Pusztai-Carey, Gregory A Sword
Pesticide resistance represents a major challenge to global food production. The spread of resistance alleles is the primary explanation for observations of reduced pesticide efficacy over time, but the potential for gene-by-environment interactions (plasticity) to mediate susceptibility has largely been overlooked. Here we show that nutrition is an environmental factor that affects susceptibility to Bt toxins. Protein and carbohydrates are two key macronutrients for insect herbivores, and the polyphagous pest Helicoverpa zea self-selects and performs best on diets that are protein-biased relative to carbohydrates...
January 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28042104/laboratory-bioassays-with-three-different-substrates-to-test-the-efficacy-of-insecticides-against-various-stages-of-drosophila-suzukii-diptera-drosophilidae
#7
Aneliya Koleva Pavlova, Melanie Dahlmann, Mirjam Hauck, Annette Reineke
Rapid worldwide spread and polyphagous nature of the spotted wing Drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae) calls for efficient and selective control strategies to prevent severe economic losses in various fruit crops. The use of insecticides is one option for management of this invasive pest insect. Efficacy of insecticides is usually assessed first in laboratory bioassays, which are compounded by the cryptic nature of D. suzukii larvae and the fact that fruits used in bioassays often start to rot and dissolve before larvae have reached the adult stage...
December 31, 2016: Journal of Insect Science
https://www.readbyqxmd.com/read/28032105/evaluation-of-some-plant-essential-oils-against-the-brown-banded-cockroach-supella-longipalpa-blattaria-ectobiidae-a-mechanical-vector-of-human-pathogens
#8
Mona Sharififard, Farhad Safdari, Amir Siahpoush, Hamid Kassiri
BACKGROUND: Essential oils, as secondary plant compounds, present a safer alternative to conventional insecticides in insect control programs. So five essential oils including eucalyptus, mint, yarrow, oregano and rosemary oils were evaluated against the brown-banded cockroach Supella longipalpa. METHODS: Evaluation was done against the 3(rd) and 4(th) instar nymphs using three bioassay methods; continuous contact toxicity, fumigant toxicity and repellent activity...
December 2016: Journal of Arthropod-borne Diseases
https://www.readbyqxmd.com/read/28019074/identification-and-detection-of-indoxacarb-resistance-mutations-in-the-para-sodium-channel-of-the-tomato-leafminer-tuta-absoluta
#9
Emmanouil Roditakis, Konstantinos Mavridis, Maria Riga, Emmanouil Vasakis, Evangelia Morou, Jean Luc Rison, John Vontas
BACKGROUND: Indoxacarb is an important active ingredient extensively used for the control of Tuta absoluta, a major tomato pest, holding a particular role in insecticide resistance management schemes. RESULTS: Reduced susceptibility to indoxacarb was identified (1794-fold resistance), through toxicological bioassays in a field population from Greece and evolved rapidly to resistance after short laboratory selection. Combined bioassays with synergists and biochemical analysis suggested only a partial involvement of detoxification enzymes in the resistant phenotype...
December 26, 2016: Pest Management Science
https://www.readbyqxmd.com/read/28011736/toxicological-enzymatic-and-molecular-assessment-of-the-insecticide-susceptibility-profile-of-triatoma-infestans-hemiptera-reduviidae-triatominae-populations-from-rural-communities-of-santa-cruz-bolivia
#10
Pablo L Santo-Orihuela, Claudia V Vassena, Guillermo Carvajal, Eva Clark, Silvio Menacho, Ricardo Bozo, Robert H Gilman, Caryn Bern, Paula L Marcet
A wide range of insecticide resistance profiles has been reported across Bolivian domestic and sylvatic populations of Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae), including some with levels proven to be a threat for vector control. In this work, the insecticide profile of domestic T. infestans was studied with standardized toxicological bioassays, in an area that has not undergone consistent vector control. F1 first-instar nymphs hatched in laboratory from bugs captured in three communities from the Santa Cruz Department were evaluated with different insecticides...
December 22, 2016: Journal of Medical Entomology
https://www.readbyqxmd.com/read/28011730/arrestant-effect-of-human-scalp-components-on-head-louse-phthiraptera-pediculidae-behavior
#11
Isabel Ortega-Insaurralde, Ariel Ceferino Toloza, Paola Gonzalez-Audino, María Inés Picollo
Relevant evidence has shown that parasites process host-related information using chemical, visual, tactile, or auditory cues. However, the cues that are involved in the host-parasite interaction between Pediculus humanus capitis (De Geer 1767) and humans have not been identified yet. In this work, we studied the effect of human scalp components on the behavior of adult head lice. Filter paper segments were rubbed on volunteers' scalps and then placed in the experimental arena, where adult head lice were individually tested...
December 23, 2016: Journal of Medical Entomology
https://www.readbyqxmd.com/read/28006032/evaluation-of-bt-corn-with-pyramided-genes-on-efficacy-and-insect-resistance-management-for-the-asian-corn-borer-in-china
#12
Fan Jiang, Tiantao Zhang, Shuxiong Bai, Zhenying Wang, Kanglai He
A Bt corn hybrid (AcIe) with two Bt genes (cry1Ie and cry1Ac) was derived by breeding stack from line expressing Cry1Ie and a line expressing Cry1Ac. Efficacy of this pyramided Bt corn hybrid against the Asian corn borer (ACB), Ostrinia furnacalis, was evaluated. We conducted laboratory bioassays using susceptible and resistant ACB strains fed on artificial diet or fresh plant tissues. We also conducted field trials with artificial infestations of ACB neonates at the V6 and silk stages. The toxin-diet bioassay data indicated that mixtures of Cry1Ac and Cry1Ie proteins had synergistic insecticidal efficacy...
2016: PloS One
https://www.readbyqxmd.com/read/27986935/bioassay-and-scanning-electron-microscopic-observations-reveal-high-virulence-of-entomopathogenic-fungus-beauveria-bassiana-on-the-onion-maggot-diptera-anthomyiidae-adults
#13
Hui Zhang, Shengyong Wu, Zhenlong Xing, Xiaoqing Wang, Zhongren Lei
When flies were dipped in 1 × 10(8) conidia/ml conidia suspensions and then kept in the incubator (22 ± 1 °C, 70 ± 5% RH), scanning electron microscope observations revealed that, at 2 h, the majority of adhering Beauveria bassiana conidia were attached to either the wing surface or the interstitial area between the macrochaetae on the thorax and abdomen of the onion maggot adults. Germ tubes were being produced and had oriented toward the cuticle by 18 h. Penetration of the insect cuticle had occurred by 36 h, and by 48 h, germ tubes had completely penetrated the cuticle...
December 2016: Journal of Economic Entomology
https://www.readbyqxmd.com/read/27983619/rna-interference-of-the-ecdysone-receptor-genes-ecr-and-usp-in-grain-aphid-sitobion-avenae-f-affects-its-survival-and-fecundity-upon-feeding-on-wheat-plants
#14
Ting Yan, Hongmei Chen, Yongwei Sun, Xiudao Yu, Lanqin Xia
RNA interference (RNAi) has been widely used in functional genomics of insects and received intensive attention in the development of RNAi-based plants for insect control. Ecdysone receptor (EcR) and ultraspiracle protein (USP) play important roles in molting, metamorphosis, and reproduction of insects. EcR and USP orthologs and their function in grain aphid (Sitobion avenae F.) have not been documented yet. Here, RT-PCR, qRT-PCR, dsRNA feeding assay and aphid bioassay were employed to isolate EcR and USP orthologs in grain aphid, investigate their expression patterns, and evaluate the effect of RNAi on aphid survival and fecundity, and its persistence...
December 14, 2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27941838/the-high-osmotic-response-and-cell-wall-integrity-pathways-cooperate-to-regulate-morphology-microsclerotia-development-and-virulence-in-metarhizium-rileyi
#15
Zhangyong Song, Qiang Zhong, Youping Yin, Ling Shen, Yan Li, Zhongkang Wang
Microsclerotia (MS) formation was successfully induced in Metarhizium rileyi under changing liquid culture conditions. Mitogen-activated protein kinases (MAPKs) play important roles in fungal development and in coordinating many stress responses. To investigate how M. rileyi transduces growth stress and regulates MS differentiation, we characterized the roles of two MAPKs, Hog1- and Slt2-type orthologues, in M. rileyi. Compared with the wild-type strain, the deletion mutants of Mrhog1 (ΔMrhog1) and Mrslt2 (ΔMrslt2) delayed germination and vegetative growth, displayed sensitivities to various stress, and produced morphologically abnormal clones...
December 12, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27920785/a-jasmonate-inducible-defense-trait-transferred-from-wild-into-cultivated-tomato-establishes-increased-whitefly-resistance-and-reduced-viral-disease-incidence
#16
Rocío Escobar-Bravo, Juan M Alba, Clara Pons, Antonio Granell, Merijn R Kant, Enrique Moriones, Rafael Fernández-Muñoz
Whiteflies damage tomatoes mostly via the viruses they transmit. Cultivated tomatoes lack many of the resistances of their wild relatives. In order to increase protection to its major pest, the whitefly Bemisia tabaci and its transmitted Tomato Yellow Leaf Curl Virus (TYLCV), we introgressed a trichome-based resistance trait from the wild tomato Solanum pimpinellifolium into cultivated tomato, Solanum lycopersicum. The tomato backcross line BC5S2 contains acylsucrose-producing type-IV trichomes, unlike cultivated tomatoes, and exhibits increased, yet limited protection to whiteflies at early development stages...
2016: Frontiers in Plant Science
https://www.readbyqxmd.com/read/27916862/contrasting-roles-of-deoxynivalenol-and-nivalenol-in-host-mediated-interactions-between-fusarium-graminearum-and-sitobion-avenae
#17
Jassy Drakulic, Mohd Haziq Kahar, Olubukola Ajigboye, Toby Bruce, Rumiana V Ray
Fusarium graminearum is the predominant causal species of Fusarium head blight in Europe and North America. Different chemotypes of the species exist, each producing a plethora of mycotoxins. Isolates of differing chemotypes produce nivalenol (NIV) and deoxynivalenol (DON), which differ in toxicity to mammals and plants. However, the effect of each mycotoxin on volatile emissions of plant hosts is not known. Host volatiles are interpreted by insect herbivores such as Sitobion avenae, the English grain aphid, during host selection...
November 30, 2016: Toxins
https://www.readbyqxmd.com/read/27914919/expressing-a-moth-abcc2-gene-in-transgenic-drosophila-causes-susceptibility-to-bt-cry1ac-without-requiring-a-cadherin-like-protein-receptor
#18
Tristan Stevens, Sisi Song, John B Bruning, Amanda Choo, Simon W Baxter
Bt toxins ingested by insect pests can bind to midgut receptors and cause death, although several steps in this process remain unclear. Multiple Bt toxin receptors have been identified in Lepidoptera, including a cadherin-like protein (CaLP), which is central to several models explaining Bt toxins' mode of action. Mutations in the Plutella xylostella ATP-dependent binding cassette transporter C2 (Px-abcc2), rather than CaLP, are genetically linked with Bt Cry1Ac resistance. Here we expressed Px-abcc2 in Drosophila and performed larval bioassays to determine whether this protein acts as an effective Bt receptor...
January 2017: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/27914535/indoxacarb-biotransformation-in-the-german-cockroach
#19
Ameya D Gondhalekar, Ernesto S Nakayasu, Isabel Silva, Bruce Cooper, Michael E Scharf
Insecticides that are used for pest control undergo physical and biological (enzymatic) degradation. Indoxacarb is an oxadiazine class sodium channel blocker insecticide used for German cockroach (Blattella germanica L.) control. At present, no information is available on enzymatic biotransformation or metabolism of indoxacarb in this important urban pest. We studied the biotransformation pathways of indoxacarb in one susceptible and three field strains with varying susceptibility levels using liquid chromatography and high-resolution mass spectrometry...
November 2016: Pesticide Biochemistry and Physiology
https://www.readbyqxmd.com/read/27910106/identification-of-semiochemicals-attractive-to-simulium-vittatum-is-7
#20
G G Verocai, T W McGAHA, J P Iburg, C R Katholi, E W Cupp, R Noblet, T R Unnasch
Many blackfly species (Diptera: Simuliidae) are economically important insect pests, both as nuisance biters and as vectors of pathogens of medical and veterinary relevance. Among the important blackfly pest species in North America is Simulium vittatum Zetterstedt sensu lato. The objective of this study was to identify compounds excreted by mammalian hosts that are attractive to host-seeking S. vittatum females. The attractiveness of putative compounds to colonized S. vittatum was tested through electrophysiological (electroantennography; n = 58 compounds) and behavioural (Y-tube assays; n = 7 compounds in three concentrations) bioassays...
December 2, 2016: Medical and Veterinary Entomology
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