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Insect Bioassay

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https://www.readbyqxmd.com/read/28428873/a-maize-landrace-that-emits-defense-volatiles-in-response-to%C3%A2-herbivore-eggs-possesses-a-strongly-inducible-terpene-synthase-gene
#1
Amanuel Tamiru, Toby J A Bruce, Annett Richter, Christine M Woodcock, Charles A O Midega, Jörg Degenhardt, Segenet Kelemu, John A Pickett, Zeyaur R Khan
Maize (Zea mays) emits volatile terpenes in response to insect feeding and egg deposition to defend itself against harmful pests. However, maize cultivars differ strongly in their ability to produce the defense signal. To further understand the agroecological role and underlying genetic mechanisms for variation in terpene emission among maize cultivars, we studied the production of an important signaling component (E)-caryophyllene in a South American maize landrace Braz1006 possessing stemborer Chilo partellus egg inducible defense trait, in comparison with the European maize line Delprim and North American inbred line B73...
April 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28424845/the-regulatory-role-of-the-transcription-factor-crz1-in-stress-tolerance-pathogenicity-and-its-target-gene-expression-in-metarhizium-acridum
#2
Xing Chen, Yuanze Liu, Nemat O Keyhani, Yuxian Xia, Yueqing Cao
In fungi, the Ca(2+)/calcineurin signaling pathway is critical in mediating growth, morphology, stress responses, and pathogenicity. Crz1 is a calcineurin-responsive zinc finger transcription factor. Here, MaCrz1 was identified and functionally characterized in the entomopathogenic fungus Metarhizium acridum by characterization of a targeted gene knockout strain. Conidia of the ΔMacrz1 mutant were aberrant in cell surface features and lacked the characteristic hydrophobic rodlet layer, and the mutant displayed increased sensitivity to oxidative stress, cell wall perturbing agents, heat stress, and ultraviolet irradiation as compared to the wild-type and complemented strains...
April 19, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28423427/influence-of-temperature-and-relative-humidity-on-the-insecticidal-efficacy-of-metarhizium-anisopliae-against-larvae-of-ephestia-kuehniella-lepidoptera-pyralidae-on-wheat
#3
Christos G Athanassiou, Nickolas G Kavallieratos, Christos I Rumbos, Demetrius C Kontodimas
A series of laboratory bioassays were conducted for the evaluation of the insecticidal efficacy of an isolate of Metarhizium anisopliae (Metschnikoff) Sorokin (Ascomycota: Hypocreales) against larvae of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), under various temperature-relative humidity (r.h.) conditions. The fungus was applied at four doses (0, 8 × 106, 8 × 108, and 8 × 1010 conidia ml-1) on wheat and insect mortality was assessed after exposure of 1, 2, 7, and 14 d...
January 1, 2017: Journal of Insect Science
https://www.readbyqxmd.com/read/28417946/essential-oils-of-hyptis-pectinata-chemotypes-isolation-binary-mixtures-and-acute-toxicity-on-leaf-cutting-ants
#4
Rosana B Feitosa-Alcantara, Leandro Bacci, Arie F Blank, Péricles B Alves, Indira Morgana de A Silva, Caroline A Soares, Taís S Sampaio, Paulo Cesar de L Nogueira, Maria de Fátima Arrigoni-Blank
Leaf-cutting ants are pests of great economic importance due to the damage they cause to agricultural and forest crops. The use of organosynthetic insecticides is the main form of control of these insects. In order to develop safer technology, the objective of this work was to evaluate the formicidal activity of the essential oils of two Hyptis pectinata genotypes (chemotypes) and their major compounds on the leaf-cutting ants Acromyrmex balzani Emery and Atta sexdens rubropilosa Forel. Bioassays of exposure pathways (contact and fumigation) and binary mixtures of the major compounds were performed...
April 12, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28398263/efficacy-of-ozone-against-phosphine-susceptible-and-resistant-strains-of-four-stored-product-insect-species
#5
Xinyi E, Bhadriraju Subramanyam, Beibei Li
The efficacy of ozone was evaluated against four economically-important stored-product insect species at 27.2 C and 20.4% r.h. Adults of phosphine-susceptible laboratory strains and phosphine-resistant field strains of the red flour beetle, Tribolium castaneum (Herbst), saw-toothed grain beetle, Oryzaephilus surinamensis (Linnaeus), maize weevil, Sitophilus zeamais Motschulsky, and rice weevil, Sitophilusoryzae (Linnaeus), were exposed in vials to an ozone concentration of 0.42 g/m³ (200 ppm) for 1, 2, 3, 5, 6, 8, 10 and 12 h with 0 and 10 g of wheat...
April 11, 2017: Insects
https://www.readbyqxmd.com/read/28383719/phosphine-resistance-in-cryptolestes-ferrugineus-coleoptera-laemophloeidae-collected-from-grain-storage-facilities-in-oklahoma-usa
#6
C E Konemann, Z Hubhachen, G P Opit, S Gautam, N S Bajracharya
Phosphine gas (PH3) is one of the most commonly used fumigants for controlling stored-grain pests worldwide. We estimated the discriminating dose for Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) adult insects using a laboratory susceptible strain. This discriminating dose was then used to determine presence or absence of PH3 resistance (resistance frequencies) in 19 field-collected populations of C. ferrugineus from Oklahoma, United States. The discriminating dose was estimated as 56.2 ppm of PH3 over a 20-h exposure period at 25 °C...
April 5, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28369429/geographic-variation-in-phosphine-resistance-among-north-american-populations-of-the-red-flour-beetle-coleoptera-tenebrionidae
#7
A J Cato, Brent Elliott, Manoj K Nayak, Thomas W Phillips
The red flour beetle, Tribolium castaneum (Herbst), is a common stored-product pest found worldwide. Phosphine, hydrogen phosphide (PH3), is the most commonly used fumigant for stored grains, for which genetically based resistance has been recorded for several pest species. This study assessed phosphine resistance in 25 T. castaneum populations from across the United States and Canada using a discriminating dose bioassay. Dose-mortality assays were conducted with adults from seven of these populations to categorize weak and strong resistance phenotypes...
March 25, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28369319/thiamethoxam-toxicity-and-effects-on-consumption-behavior-in-orius-insidiosus-hemiptera-anthocoridae-on-soybean
#8
Carolina Camargo, Thomas E Hunt, Loren J Giesler, Blair D Siegfried
Neonicotinoid residues can be present in soybean vegetative tissue, prey insects, and flower tissues, possibly making them toxic to pollinators and natural enemies. Baseline information on the toxicity of neonicotinoids to beneficial insects other than pollinators through multiple routes of insecticide exposure is limited. The objectives of this study were 1) to evaluate the toxicity of thiamethoxam to the hemipteran predator, Orius insidiosus Say, exposed to residues through treated vegetative tissue and insect prey, and 2) to evaluate the effect of thiamethoxam on the abundance of this predator species in soybean fields...
March 20, 2017: Environmental Entomology
https://www.readbyqxmd.com/read/28363958/toxicity-and-binding-studies-of-bacillus-thuringiensis-cry1ac-cry1f-cry1c-and-cry2a-proteins-in-the-soybean-pests-anticarsia-gemmatalis-and-chrysodeixis-pseudoplusia-includens
#9
Yolanda Bel, Joel J Sheets, Sek Yee Tan, Kenneth E Narva, Baltasar Escriche
Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybean. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins can be used and are increasingly being adopted. Studies on the insect susceptibility and mode of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance...
March 31, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28362364/a-method-for-evaluating-insecticide-efficacy-against-bed-bug-cimex-lectularius-eggs-and-first-instars
#10
Brittany E Campbell, Dini M Miller
Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or concentration-response curve, where mortality increases as the dose or concentration of an insecticide is increased. Standard lethal concentration (LC50) and lethal dose (LD50) tests that result in 50% mortality of a test population can be challenging for evaluating toxicity of insecticides against non-adult insect life stages, such as eggs and early instar or nymphal stages...
March 15, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28353149/toxicity-of-an-annonin-based-commercial-bioinsecticide-against-three-primary-pest-species-of-stored-products
#11
L P Ribeiro, O Z Zanardi, G L P Gonçalves, T F Ansante, P T Yamamoto, J D Vendramim
The effects of a bioinsecticide formulation based on extract of Annona squamosa L. (Annonaceae) containing 10,000 mg L(-1) of acetogenin annonin as the main active ingredient were investigated against three primary pest species of stored grains in Brazil [maize weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), Mexican bean weevil Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae: Bruchinae), and cowpea weevil Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae: Bruchinae)] by means of residual contact bioassays...
March 28, 2017: Neotropical Entomology
https://www.readbyqxmd.com/read/28352969/transgenic-pigeonpea-events-expressing-cry1ac-and-cry2aa-exhibit-resistance-to-helicoverpa-armigera
#12
Gourab Ghosh, Shreeparna Ganguly, Arnab Purohit, Rituparna Kundu Chaudhuri, Sampa Das, Dipankar Chakraborti
Independent transgenic pigeonpea events were developed using two cry genes. Transgenic Cry2Aa-pigeonpea was established for the first time. Selected transgenic events demonstrated 100% mortality of Helicoverpa armigera in successive generations. Lepidopteran insect Helicoverpa armigera is the major yield constraint of food legume pigeonpea. The present study was aimed to develop H. armigera-resistant transgenic pigeonpea, selected on the basis of transgene expression and phenotyping. Agrobacterium tumefaciens-mediated transformation of embryonic axis explants of pigeonpea cv UPAS 120 was performed using two separate binary vectors carrying synthetic Bacillus thuringiensis insecticidal crystal protein genes, cry1Ac and cry2Aa...
March 28, 2017: Plant Cell Reports
https://www.readbyqxmd.com/read/28330080/transgenic-rice-plants-expressing-synthetic-cry2ax1-gene-exhibits-resistance-to-rice-leaffolder-cnaphalocrosis-medinalis
#13
R Manikandan, N Balakrishnan, D Sudhakar, V Udayasuriyan
Bacillus thuringiensis is a major source of insecticidal genes imparting insect resistance in transgenic plants. Level of expression of transgenes in transgenic plants is important to achieve desirable level of resistance against target insects. In order to achieve desirable level of expression, rice chloroplast transit peptide sequence was fused with synthetic cry2AX1 gene to target its protein in chloroplasts. Sixteen PCR positive lines of rice were generated by Agrobacterium mediated transformation using immature embryos...
June 2016: 3 Biotech
https://www.readbyqxmd.com/read/28321527/effects-of-site-mutations-within-the-22%C3%A2-kda-no-core-fragment-of-the-vip3aa11-insecticidal-toxin-of-bacillus-thuringiensis
#14
Ming Liu, Rongmei Liu, Guoxing Luo, Haitao Li, Jiguo Gao
Bacillus thuringiensis vegetative insecticidal proteins (VIPs) are not homologous to other known Cry proteins, and they act against lepidopteran larvae via a unique process. All reported studies on the mode of action of Vip3 proteins have been performed on the Vip3A family, mostly on the Vip3Aa subfamily. Vip3Aa proteins are activated by midgut proteases, and they cross the peritrophic membrane and bind specific proteins in apical membrane epithelial midgut cells, which results in pore formation and, eventually, death to the insects...
May 2017: Current Microbiology
https://www.readbyqxmd.com/read/28316131/evaluation-of-potential-rna-interference-target-genes-to-control-cotton-mealybug-phenacoccus-solenopsis-hemiptera-pseudococcuidae
#15
Arif M Khan, Muhammad Ashfaq, Azhar A Khan, Muhammad T Naseem, Shahid Mansoor
RNA interference (RNAi) of vital insect genes is a potential tool for targeted pest control. However, selection of the right target genes is a challenge because the RNAi efficacy is known to vary among insect species. Cotton mealybug, Phenacoccus solenopsis, is a phloem-feeding economically important crop pest. We evaluated the RNAi of two vital genes, Bursicon (PsBur) and V-ATPase (PsV-ATPase) as potential targets in P. solenopsis for its control. PCR fragments of PsBur and PsV-ATPase were amplified using cDNA synthesized from the total RNA...
March 18, 2017: Insect Science
https://www.readbyqxmd.com/read/28303034/searching-for-wheat-resistance-to-aphids-and-wheat-bulb-fly-in-the-historical-watkins-and-gediflux-wheat-collections
#16
G I Aradottir, J L Martin, S J Clark, J A Pickett, L E Smart
Insect pests can reduce wheat yield by direct feeding and transmission of plant viruses. Here we report results from laboratory and field phenotyping studies on a wide range of wheat, including landraces from the Watkins collection deriving from before the green revolution, more modern cultivars from the Gediflux collection (north-western Europe) and modern UK Elite varieties, for resistance to the bird cherry-oat aphid, Rhopalosiphum padi (Homoptera: Aphididae) and the English grain aphid, Sitobion avenae (Homoptera: Aphididae)...
March 2017: Annals of Applied Biology
https://www.readbyqxmd.com/read/28279191/effectiveness-of-autodissemination-stations-containing-pyriproxyfen-in-reducing-immature-aedes-albopictus-populations
#17
Isik Unlu, Devi S Suman, Yi Wang, Kim Klingler, Ary Faraji, Randy Gaugler
BACKGROUND: Aedes albopictus, the Asian tiger mosquito, is an aggressive, highly anthropophilic, day-biting mosquito with an expanding geographic range. Suppression of Ae. albopictus is difficult because of the abundance and prevalence of larval habitats within peridomestic environments, particularly cryptic habitats such as corrugated extension spouts, fence post openings, discarded food containers, etc. Because of the challenges of eliminating or treating larval habitats of this species, we tested an autodissemination concept to contaminate these habitats with the insect growth regulator pyriproxyfen...
March 9, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28266104/larvicidal-activity-of-synthetic-tropane-alkaloids-against-ascia-monuste-orseis-lepidoptera-pieridae
#18
Simone Z Mairink, Luiz Ca Barbosa, Eduardo Vv Varejão, Elizeu S Farias, Márcio Lm Santos, Marcelo C Picanço
BACKGROUND: Tropane alkaloids are well known to play a role in plant defense. By blocking acetylcholine receptors, they exert insecticidal and deterrent effects against herbivore insects. Carbamates are an important class of chemical insecticides that also inhibit acetyl cholinesterase. The objective of this work was to synthesize a series of tropane alkaloids bearing a carbamate group, and to evaluate their effects against the pest Ascia monuste. The effects of the most active compounds were evaluated on the A...
March 6, 2017: Pest Management Science
https://www.readbyqxmd.com/read/28258772/insect-deterrent-and-nematicidal-screening-of-microfungi-from-mexico-and-anti-aphid-compounds-from-gliomastix-masseei
#19
Ana L Ruiz-Jiménez, Azucena González-Coloma, Mari Fe Andrés-Yeves, Esaú Ruiz-Sánchez, Gabriela Heredia, Sergio R Peraza-Sánchez, Irma L Medina-Baizabal, Manuela Reyes-Estebanez, Blondy Canto-Canché, Marcela Gamboa-Angulo
Fungal metabolites are promising alternatives for the development of biorational pesticides. In this sense, microfungi from tropical regions are valuable sources of natural compounds for pest management. With the aim of broadening the search for new eco-friendly products to manage plant pests, this study was carried out to evaluate the biological activity of 23 tropical fungal extracts on three species of phytophagous insects and a plant parasitic nematode. In addition, the active principles of the most effective extract were identified...
February 28, 2017: Revista Argentina de Microbiología
https://www.readbyqxmd.com/read/28247562/design-synthesis-and-insecticidal-activity-of-novel-hydrocarbylidene-nitrohydrazinecarboximidamides
#20
Yong Xu, Dong-Yan Yang, Xiang-Gao Zou, Chang-Hui Rui, Zi-Yuan Zhou, Yong-Qiang Ma, Zhao-Hai Qin
BACKGROUND: Neonicotinoids, among the most important pesticides in recent decades, have played pivotal roles in controlling agricultural pests. However, the toxicity to some environmentally beneficial insects is a cause of concern. The development of novel insecticides safer to these insects is increasingly urgent. RESULTS: A novel series of hydrocarbylidene nitrohydrazinecarboximidamides were designed and synthesised, starting from S-methylisothiourea sulphate...
March 1, 2017: Pest Management Science
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