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Insect Bioassay

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
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
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...
November 30, 2016: Insect Biochemistry and Molecular Biology
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
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
Amy M Trowbridge, M Deane Bowers, Russell K Monson
Changes in the chemical composition of plant defense compounds during herbivory can impact herbivore resource allocation patterns and thereby herbivore survival, growth, and immune response against endoparasitoid infection. Few studies have investigated folivore responses to changes in plant chemistry that occur under outbreak conditions in mature conifer systems. Using data from an earlier observational field study, we carried out laboratory bioassays to test how variation in monoterpenes in piñon pine trees (Pinus edulis, Pinaceae) during an outbreak affects growth, consumption, and immune response of a specialist herbivore, the Southwestern tiger moth (Lophocampa ingens, Arctiidae)...
December 1, 2016: Journal of Chemical Ecology
Rajendra Prasad Mondal, Goutam Chandra, Subhasis Bandyopadhyay, Anupam Ghosh
Present study was carried out to establish the influence of abiotic factors on foraging activities of a predatory hemipteran insect Anisops sardea against Anopheles stephensi larvae. The functional response of A. sardea was evaluated in variable density of prey items with variation in search area (100, 250, 500 and 1000ml water volume) and temperatures (20, 25 and 30°C). The results of laboratory bioassay revealed that prey consumption rate of predator species was positively related with increasing temperature and inversely related with increasing search area...
November 28, 2016: Acta Tropica
María Claudia Atencia, María De Jesús Pérez, María Cristina Jaramillo, Sandy Milena Caldera, Suljey Cochero, Eduar Elías Bejarano
The main strategy for the control of Aedes aegypti, vector of dengue, chikungunya and Zika viruses, is based on the use of insecticides to reduce its populations. However, their use has led to insect resistance to these chemicals. Objective: To determine the presence of the F1534C mutation associated with cross-resistance to DDT and pyrethroids in A. aegypti in Sincelejo, Colombia. Materials and methods: We studied nine specimens of A. aegypti that showed resistance to lambdacyhalothrin in bioassays developed by the Secretaría de Salud de Sucre...
September 1, 2016: Biomédica: Revista del Instituto Nacional de Salud
Yu-Chen Pu, Tian-Ling Ma, You-Ming Hou, Ming Sun
BACKGROUND: The red palm weevil (RPW), Rhynchophorus ferrugineus, is an invasive wood-boring insect that damages palms and sugarcane. Bacillus thuringiensis (Bt), is an entomopathogenic bacterium which has been modified into various strains, and widely used in pest management. The aim of this study was to evaluate the susceptibility of RPW to the HA strain of Bt. RESULTS: Five concentrations of Bt bioassays were used on RPW eggs, 2(nd) and 4(th) instars. Average egg hatching rates exceeded 85% using Bt suspensions or distilled water...
November 14, 2016: Pest Management Science
Fei Yang, Mao Chen, Anilkumar Gowda, David L Kerns, Fangneng Huang
The sugarcane borer, Diatraea saccharalis (F.), is a major maize borer pest and a target of transgenic maize expressing Bacillus thuringiensis (Bt) proteins in South America and the mid-southern region of the U.S. Evolution of resistance in target pest populations is a great threat to the long-term efficacy of Bt crops. In this study, we compared the genetic basis of resistance to Cry1Ab protein in three resistant colonies of sugarcane borer established from field populations in Louisiana, USA. Responses of larvae to the Cry1Ab protein for the parental and ten other cross colonies were assayed in a diet-incorporated bioassay...
November 8, 2016: Insect Science
Vanessa Karine Schneider, Andrea Soares-Costa, Mohan Chakravarthi, Carolina Ribeiro, Sabrina Moutinho Chabregas, Maria Cristina Falco, Flavio Henrique-Silva
Transgenic sugarcane expressing CaneCPI-1 exhibits resistance to Sphenophorus levis larvae. Transgenic plants have widely been used to improve resistance against insect attack. Sugarcane is an economically important crop; however, great losses are caused by insect attack. Sphenophorus levis is a sugarcane weevil that digs tunnels in the stem base, leading to the destruction of the crop. This insect is controlled inefficiently by chemical insecticides. Transgenic plants expressing peptidase inhibitors represent an important strategy for impairing insect growth and development...
November 11, 2016: Plant Cell Reports
Fei Ling, Fei Zhou, Hao Chen, Yongjun Lin
Agrobacterium-mediated co-transformation is an efficient strategy to generate marker-free transgenic plants. In this study, the vectors pMF-2A(∗) containing a synthetic cry2A(∗) gene driven by maize ubiquitin promoter and pCAMBIA1301 harboring hygromycin phosphotransferase gene (hpt) were introduced into Minghui86 (Oryza sativa L. ssp. indica), an elite indica restorer line. Two independent transformants containing both the cry2A(∗) gene and hpt gene were regenerated. Several homozygous marker-free transgenic progenies were derived from family 2AH2, and three of them were selected for further insect bioassay in the laboratory and field...
2016: Frontiers in Plant Science
Yusuke Sumita, Hitoshi Kawada, Noboru Minakawa
We investigated the mode of entry of pyrethroids into the insect body using adult housefly, Musca domestica L., as an insect model. The wings of adult female houseflies were removed, and empenthrin was applied topically to three different sites: the mesothoracic spiracle, the ventral mesothorax, and the dorsal mesothorax. Among these treatments, the application of the compound to the mesothoracic spiracle led to the quickest knockdown of the flies. To determine the importance of the spiracle as a primary entry site for the pyrethroid, knockdown times were compared between houseflies with blocked and non-blocked spiracles, using two bioassays: a vapor action test using technical grade empenthrin, and a mosquito coil test using empenthrin-impregnated coils...
2016: Applied Entomology and Zoology
Mark A Kartzinel, Barry W Alto, Michael W Deblasio, Nathan D Burkett-Cadena
Three exotic mosquito-borne pathogens-dengue, chikungunya, and Zika viruses-transmitted by Aedes albopictus and Ae. aegypti have undergone dramatic global expansion in recent years. The control of vector populations and minimizing bites from these vectors are the primary methods of reducing risk of transmission of these viruses to humans. However, Ae. albopictus and Ae. aegypti are notoriously challenging to control through conventional chemical means, due primarily to difficulties in applying pesticides to their cryptic larval habitats...
September 2016: Journal of the American Mosquito Control Association
Christopher S Bibbs, Codi Anderson, Rui-De Xue
Recent autodissemination studies have popularly favored pyriproxyfen, but methoprene is already established and widely used in control programs. This study demonstrated that methoprene could also autodisseminate through contaminated gravid females. Arenas of oviposition cups were arranged around methoprene-contaminated bait stations. Gravid female Aedes albopictus were released to allow oviposition. All cups were then removed and tested in an insect growth regulator bioassay. Liquid formulations did not result in adequate autodissemination among treatment groups...
September 2016: Journal of the American Mosquito Control Association
Bing Guo, Yongqiang Zhang, Shili Li, Ting Lai, Liang Yang, Juanni Chen, Wei Ding
Many cereals accumulate hydroxamic acids involved in defense of plant against various fungi, bacteria, and insects. 2,4-dihydroxy-7-methoxy-1,4-benzoxazine-3-one, commonly known as DIMBOA, is one of the principal cyclic hydroxamic acids in aqueous extracts of maize. The aim of this study was to evaluate the antibacterial activity of the isolated DIMBOA and its derivatives 2-benzoxazolinone (BOA), 6-chloro-2-benzoxazolinone (CDHB), and 2-mercaptobenzothiazole (MBT) against Ralstonia solanacearum. MBT showed the strongest antibacterial activity, followed by CDHB and DIMBOA, with minimum inhibitory concentrations (MICs) of 50, 100 and 200 mg/L, respectively, better than the BOA with 300 mg/L...
October 19, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Alemayehu Teressa Negawo, Linda Baranek, Hans-Jörg Jacobsen, Fathi Hassan
Transgenic pea lines transformed with the cry1Ac gene were characterized at molecular (PCR, RT-PCR, qRT-PCR and immunostrip assay) and functional levels (leaf paint and insect feeding bioassays). The results showed the presence, expression, inheritance and functionality of the introduced transgene at different progeny levels. Variation in the expression of the cry1Ac gene was observed among the different transgenic lines. In the insect bioassay studies using the larvae of Heliothis virescens, both larval survival and plant damage were highly affected on the different transgenic plants...
October 20, 2016: GM Crops & Food
Rebecca A Schmidt-Jeffris, Brian A Nault
Many vegetable insect pests are managed using neonicotinoid and pyrethroid insecticides. Unfortunately, these insecticides are toxic to many bees and natural enemies and no longer control some pests that have developed resistance. Anthranilic diamide insecticides provide systemic control of many herbivorous arthropod pests, but exhibit low toxicity to beneficial arthropods and mammals, and may be a promising alternative to neonicotinoids and pyrethroids. Anthranilic diamides may be delivered to vegetable crops via seed, in-furrow, or foliar treatments; therefore, it would be desirable to identify which application method provides high levels of pest control while minimizing the amount of active ingredient...
October 19, 2016: Journal of Economic Entomology
Gillian Hertlein, Marlene Seiffert, Sebastian Gensel, Eva Garcia-Gonzalez, Julia Ebeling, Ranko Skobalj, Anja Kuthning, Roderich D Süssmuth, Elke Genersch
The Gram-positive bacterium Paenibacillus larvae (P. larvae) is the causative agent of a deadly honey bee brood disease called American Foulbrood (AFB). AFB is a notifiable epizootic in most countries and, hence, P. larvae is of considerable relevance for veterinarians and apiculturists alike. Over the last decade, much progress has been made in the understanding of the (patho)biology of P. larvae. Recently, several non-ribosomally produced peptides (NRP) and peptide/polyketide (NRP/PK) hybrids produced by P...
2016: PloS One
Madeleine Berger, Alin Mirel Puinean, Emma Randall, Christoph T Zimmer, Wellington M Silva, Pablo Bielza, Linda M Field, David Hughes, Ian Mellor, Keywan Hassani-Pak, Herbert A A Siqueira, Martin S Williamson, Chris Bass
Many genes increase coding capacity by alternate exon usage. The gene encoding the insect nicotinic acetylcholine receptor (nAChR) α6 subunit, target of the bio-insecticide spinosad, is one example of this and expands protein diversity via alternative splicing of mutually exclusive exons. Here, we show that spinosad resistance in the tomato leaf miner, Tuta absoluta is associated with aberrant regulation of splicing of Taα6 resulting in a novel form of insecticide resistance mediated by exon skipping. Sequencing of the α6 subunit cDNA from spinosad selected and unselected strains of T...
November 2016: Molecular Ecology
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