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Insect Bioassay

Shengyan Li, Zeyu Wang, Yiyao Zhou, Changhui Li, Guiping Wang, Hai Wang, Jie Zhang, Gemei Liang, Zhihong Lang
To improve the novel Bacillus thuringiensis insecticidal gene cry2Ah1 toxicity, two mutants cry2Ah1-vp (V354VP) and cry2Ah1-sp (V354SP) were performed. SWISS-MODEL analysis showed two mutants had a longer loop located between β-4 and β-5 of domain II, resulting in higher binding affinity with brush border membrane vesicles (BBMV) of Helicoverpa armigera comparing with Cry2Ah1. The cry2Ah1, cry2Ah1-vp, and cry2Ah1-sp were optimized codon usage according to plant codon bias, and named mcry2Ah1, mcry2Ah1-vp, and mcry2Ah1-sp...
January 11, 2018: Scientific Reports
Muhammad Zeeshan Shabbir, Yudong Quan, Zhenying Wang, Alejandra Bravo, Mario Soberón, Kanglai He
Transgenic crops producing insecticidal proteins are effective to manage lepidopteran pests. Development of insect-resistance is the major threat to Bacillus thuringiensis (Bt) crops such as Cry1Ah-Maize. Laboratory selection with Bt-Cry1Ah toxin incorporated in artificial diet, during 48 generations of Asian corn borer (ACB) Ostrinia furnacalis produced 200-fold resistance. This resistant colony ACB-AhR readily consumed and survived on Cry1Ah-expressing Bt-maize. Cross-resistance analysis showed high cross-resistance to Cry1F (464-fold), moderate cross-resistance to Cry1Ab (28...
January 10, 2018: Scientific Reports
Chengkai Lu, Jinfeng Qi, Christian Hettenhausen, Yunting Lei, Jingxiong Zhang, Mou Zhang, Cuiping Zhang, Juan Song, Jing Li, Guoyan Cao, Saif Ul Malook, Jianqiang Wu
Atmospheric CO2 levels are rapidly increasing due to human activities. However, the effects of elevated CO2 (ECO2 ) on plant defense against insects and the underlying mechanisms remain poorly understood. Here we show that ECO2 increased the photosynthetic rates and the biomass of tobacco and rice plants, and the chewing lepidopteran insects Spodoptera litura and Mythimna separata gained less and more mass on tobacco and rice plants, respectively. Consistently, under ECO2 , the levels of jasmonic acid (JA), the main phytohormone controlling plant defense against these lepidopteran insects, as well as the main defense-related metabolites, were increased and decreased in insect-damaged tobacco and rice plants...
January 10, 2018: Journal of Integrative Plant Biology
Huifang Wang, Zhangjiang He, Linli Luo, Xin Zhao, Zhuoyue Lu, Tingying Luo, Min Li, Yongjun Zhang
The aldo-keto reductases (AKRs) belong to the NADP-dependent oxidoreductase superfamily, which play important roles in various physiological functions in prokaryotic and eukaryotic organisms. However, many AKR superfamily members remain uncharacterized. Here, a downstream target gene of the HOG1 MAPK pathways coding for an aldo-keto reductase, named Bbakr1, was characterized in the insect fungal pathogen, Beauveria bassiana. Bbakr1 expression increased in response to osmotic and salt stressors, and oxidative and heavy metal (chromium) stress...
January 3, 2018: Fungal Genetics and Biology: FG & B
Bharat Nareshkumar, Shaik Mohammad Akbar, Hari Chand Sharma, Senigala K Jayalakshmi, Kuruba Sreeramulu
Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) and are frequently used as insecticides against most devastating lepidopteran insect pests. Imidacloprid influenced dose-dependent decline in the state III and IV respiration, respiration control index (RCI), and P/O ratios, in vitro and in vivo. The bioassay indicated its LD50 value to be 531.24 μM. The insecticide exhibited a dose-dependent inhibition on F0F1-ATPase and complex IV activity. At 600 μM, the insecticide inhibited 83...
January 5, 2018: Journal of Bioenergetics and Biomembranes
Elaine A Backus, Felix A Cervantes, Larry Godfrey, Waseem Akbar, Thomas L Clark, Maria G Rojas
This study is the first to fully evaluate whether electrical signals applied to large insects during electropenetrography (EPG; also called electrical penetration graph) negatively affect insect behavior. During EPG, electrical signals are applied to plants, and thus to the gold-wire-tethered insects feeding on them. The insect completes an electrical circuit whose changes in voltage reflect the insect's stylet probing/penetration behaviors, recorded as waveform output. For nearly 50 years of EPG science, evidence has supported that there are no or negligible effects on tiny insects from applied electricity during EPG...
December 29, 2017: Journal of Insect Physiology
M V Calvo, H F Groba, G Martínez, C Sellanes, C Rossini, A González
The bronze bug, Thaumastocoris peregrinus Carpintero & Dellape (Heteroptera: Thaumastocoridae), is an exotic emerging pest in Eucalyptus commercial forests in South America, Africa and southern Europe. Information on the chemical communication system and reproductive ecology of this insect is scant, and it may be relevant for designing management strategies for eucalypt plantations. Adults and nymphs usually aggregate in the field, possibly by means of chemical signals. Males emit large amounts of 3-methyl-2-butenyl butyrate, which attracts conspecific adult males but not females...
December 23, 2017: Neotropical Entomology
Isik Unlu, Gregory M Williams, Ilia Rochlin, Devi Suman, Yi Wang, Kshitij Chandel, Randy Gaugler
Mosquito control programs in the United States are still searching for best management practices to control the Asian tiger mosquito, Aedes albopictus (Skuse; Diptera: Culicidae). Most intervention methods for this species are either labor intensive (e.g., source reduction) or short-term (e.g., ultra-low-volume adulticiding). We investigated the effectiveness of barrier spray pesticide applications within urban and suburban residential yards in New Jersey as a control strategy using a before-after-control-impact (BACI) approach...
December 13, 2017: Journal of Medical Entomology
David A Ingber, Charles E Mason, Lindsey Flexner
The fall armyworm, Spodoptera frugiperda (Smith; Lepidoptera: Noctuidae), is a highly polyphagous, multivoltine pest of commercial crops including corn (Zea mays L.), cotton (Gossypium spp. L.), rice (Oryza sativa L.), and pasture grasses. Fall armyworm has become a growing concern in agricultural communities across the Americas as field populations in many locales have evolved resistance to several Cry1 toxins derived from the bacterium Bacillus thuringiensis Berliner (Bt). An often overlooked aspect of fall armyworm biology is the existence of two host strains, the 'rice' and 'corn' strains...
December 12, 2017: Journal of Economic Entomology
Suellen Rodrigues Ramalho, Cezar da Silva Bezerra, Daniella Gorete Lourenço de Oliveira, Letícia Souza Lima, Simone Maria Neto, Caio Fernando Ramalho de Oliveira, Newton Valério Verbisck, Maria Lígia Rodrigues Macedo
A novel Kunitz-type inhibitor from Platypodium elegans seeds (PeTI) was purified and characterized. The mass spectrometry analyses of PeTI indicated an intact mass of 19,701 Da, and a partial sequence homologous to Kunitz inhibitors. PeTI was purified by ion exchange and affinity chromatographies. A complex with a 1:1 ratio was obtained only for bovine trypsin, showing a Ki = 0.16 nM. Stability studies showed that PeTI was stable over a wide range of temperature (37-80 °C) and pH (2-10). The inhibitory activity of PeTI was affected by dithiothreitol (DTT)...
December 14, 2017: Journal of Agricultural and Food Chemistry
Thomson M Paris, Sandra A Allan, Bradley J Udell, Philip A Stansly
The Asian citrus psyllid, Diaphorina citri, vectors huanglongbing (HLB), the most serious disease affecting citrus globally. D. citri and HLB have spread to the major citrus growing regions of North America causing billions of dollars of damage in Florida alone. The visual behavior of D. citri is not well characterized and more knowledge is needed to improve attractive traps for monitoring and control of the D. citri. Bioassays were conducted to evaluate attraction to light transmitted through different colored filters...
2017: PloS One
Showkat Ahmad Lone, Abdul Malik, Jasdeep Chatrath Padaria
Vegetative insecticidal proteins represent the second generation of insecticidal trans-genes that will complement the delta endotoxins in future. A new vip3A gene was cloned from the promising native isolate, Bacillus thuringiensis JK37 obtained from the soils of maize field. The entire coding sequence of the gene (2370 bp) was amplified and cloned into pET28a(+) expression vector. The nucleotide sequence analysis revealed that deduced amino acid sequence had a variation of several amino acid residues compared to those of known Vip3A proteins and this gene was designated as vip3Aa61 by the B...
December 9, 2017: Microbial Pathogenesis
Nobuhiko Oki, Akito Kaga, Takehiko Shimizu, Masakazu Takahashi, Yuhi Kono, Motoki Takahashi
The common cutworm (CCW; Spodoptera litura Fabricius) is a serious herbivorous insect pest of soybean (Glycine max) in Asia and Oceania. Previously, we identified quantitative trait loci (QTLs) for CCW-antibiosis-resistance, CCW-1 and CCW-2, and antixenosis-resistance, qRslx1 and qRslx2, in the cultivar 'Himeshirazu'. The effects of these QTLs are useful in the breeding of CCW-resistant cultivars. In this study, we conducted an antixenosis bioassay on CCW using recombinant inbred lines derived from a cross between a wild soybean (Glycine soja) and the leading cultivar 'Fukuyutaka' to identify CCW-resistance genes in G...
2017: PloS One
Stefano Pasquini, Marie Odile Haxaire-Lutun, Jean-Luc Rison, Wilbert G Flier, Luis A Teixeira
The European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), is regarded as the most important insect pest of wine grapes in Europe. If not properly controlled, it can cause significant direct and indirect yield losses due to secondary infections of grape berries by Botrytis cinerea. For these reasons, it is important to preserve the activity of insecticides used against this pest, as the number of insecticidal mode of actions available to control Lepidoptera species on wine grapes in Europe is limited...
December 8, 2017: Journal of Economic Entomology
Yuki Itoh, Yukiko Okumura, Takeshi Fujii, Yukio Ishikawa, Hisashi Ômura
Mating might significantly affect the host selection behaviors of phytophagous insects. Here, we investigated the post-mating changes in behavioral and antennal responses of Pieris rapae (Lepidoptera: Pieridae) females to host plant volatiles. In two-choice bioassays using artificial plant models, mated females visited the model scented with synthetic blends (15-, 9-, or 6-components) of cabbage plant volatiles more frequently than the unscented control, whereas virgin females did not exhibit this preference...
December 1, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
Abolfazl Masoudi, John Lad Koprowski, Upendra Raj Bhattarai, Dun Wang
Entomopathogenic fungi are considered to be a safe microbiological pesticide alternative to chemical control. Efforts are underway to understand precisely their taxonomy and natural distribution through mycological and biodiversity studies based on molecular markers. Here, we present descriptions of the diversity of the entomopathogenic fungi in the genera Metarhizium and Beauveria found along the elevational gradients of the Qinling subtropical and temperate forests of Shaanxi province in China, using morphological aspects and molecular markers...
November 30, 2017: Applied Microbiology and Biotechnology
E Afful, Brent Elliott, Manoj K Nayak, Thomas W Phillips
Phosphine is the most widely used fumigant for stored grain insect pests, and resistance to phosphine has evolved in several species worldwide. This study was designed to determine the presence of phosphine resistance in 34 populations of Rhyzopertha dominica (F.) collected from the United States and Canada. Adult R. dominica were sampled and subjected to a discriminatory dose toxicity assay of exposure to 20 ppm of phosphine for 20 h of exposure to distinguish a susceptible R. dominica adult by death from a resistant beetle that survives the treatment...
November 22, 2017: Journal of Economic Entomology
Diego B Silva, Vanda H P Bueno, Joop J A Van Loon, Maria Fernanda G V Peñaflor, José Maurício S Bento, Joop C Van Lenteren
Plants emit volatile compounds in response to insect herbivory, which may play multiple roles as defensive compounds and mediators of interactions with other plants, microorganisms and animals. Herbivore-induced plant volatiles (HIPVs) may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. We report here the first evidence of the attraction of three Neotropical mirid predators (Macrolophus basicornis, Engytatus varians and Campyloneuropsis infumatus) toward plants emitting volatiles induced upon feeding by two tomato pests, the leaf miner Tuta absoluta and the phloem feeder Bemisia tabaci, in olfactometer bioassays...
November 25, 2017: Journal of Chemical Ecology
Emma N I Weeks, Daniel R Schmehl, Julie Baniszewski, Hudson V V Tomé, James P Cuda, James D Ellis, Bruce R Stevens
Methionine is an essential/indispensible amino acid nutrient required by adult and larval honey bees (Apis mellifera L. [Hymenoptera: Apidae]). Bees are unable to rear broods on pollen deficient in methionine, and reportedly behaviorally avoid collecting pollen or nectar from florets deficient in methioinine. In contrast, it has been demonstrated that methionine is toxic to certain pest insects; thus it has been proposed as an effective biopesticide. As an ecofriendly integrated pest management agent, methionine boasts a novel mode of action differentiating it from conventional pesticides, while providing non-target safety...
November 23, 2017: Ecotoxicology and Environmental Safety
Man P Huynh, Lisa N Meihls, Bruce E Hibbard, Stephen L Lapointe, Randall P Niedz, Dalton C Ludwick, Thomas A Coudron
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is the most serious insect pest of corn (Zea mays L.) in the United States and parts of Europe, and arguably one of the world's most expensive pests to control. Several diet formulations are currently used by industry and public researchers to evaluate WCR larvae in diet-toxicity bioassays. However, a publicly available diet that produces normative insects that are physiologically similar to WCR larvae reared on corn roots will accelerate development of management technologies...
2017: PloS One
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