Distinct Impact of Processing on Cross-Order Cry1I Insecticidal Activity.

The insecticidal Cry proteins from are used in biopesticides or transgenic crops for pest control. The Cry1I protein family has unique characteristics of being produced during the vegetative rather than sporulation phase, its protoxins forming dimers in solution, and exhibiting dual toxicity against lepidopteran and coleopteran pests. The Cry1Ia protoxin undergoes sequential proteolysis from the N- and C-terminal ends, producing intermediate forms with insecticidal activity, while in some cases, the fully processed toxin is inactive.

Insecticide resistance management scenarios differ for RNA-based sprays and traits.

RNA-based bioinsecticides that comprise a dsRNA active ingredient and function by RNA interference (RNAi) are being commercialised as insecticidal traits in transgenic crops and as sprayable biopesticides. These RNAi insecticidal technologies are valuable alternatives to conventional chemical insecticides due to their efficacy, high degree of specificity and favourable human and environmental safety profiles. As with all pesticides, appropriate insect resistance management (IRM) programmes are required to mitigate the selection for resistance in target insect populations and extend product durability in the field.

Evaluation of GS-omega/kappa-Hxtx-Hv1a and Bt toxins against Bt-resistant and -susceptible strains of Helicoverpa zea (Boddie) and Spodoptera frugiperda (J.E. Smith).

Background: Helicoverpa zea and Spodoptera frugiperda are destructive insect pests of cotton and corn. Both have evolved practical resistance to transgenic crops producing Bacillus thuringiensis (Bt) toxins in the United States. GS-omega/kappa-Hxtx-Hv1a (ω/κ-Hv1a) is a novel biopesticide derived from spider venom with activity against lepidopteran pests.

Effects of Treatment on Expression of Detoxification Genes in Chlorantraniliprole-Resistant .

Detoxification genes are crucial to insect resistance against chemical pesticides, yet their expression may be altered by exposure to biopesticides such as spores and insecticidal proteins of (Bt). Increased enzymatic levels of selected detoxification genes, including glutathione S-transferase (GST), cytochrome P450 (CYP450), and carboxylesterase (CarE), were detected in chlorantraniliprole (CAP)-resistant strains of the diamondback moth (DBM, ) from China when compared to a reference susceptible strain. These CAP-resistant DBM strains displayed distinct expression patterns of GST 1, CYP6B7, and CarE-6 after treatment with CAP and a Bt pesticide (Bt-G033).

Proactive resistance management for sustaining the efficacy of RNA interference for pest control.

Biopesticides based on RNA interference (RNAi) took a major step forward with the first registration of a sprayable RNAi product, which targets the world's most damaging potato pest. Proactive resistance management is needed to delay the evolution of resistance by pests and sustain the efficacy of RNAi biopesticides.

Individual transmembrane domains of SfABCC2 from Spodoptera frugiperda do not serve as functional Cry1F receptors.

The fall armyworm (Spodoptera frugiperda) is a major global pest causing severe damage to various crops, especially corn. Transgenic corn producing the Cry1F pesticidal protein from the bacterium Bacillus thuringiensis (Cry1F corn) showed effectiveness in controlling this pest until S. frugiperda populations at locations in North and South America evolved practical resistance.

Diverse genetic basis of Vip3Aa resistance in five independent field-derived strains of Helicoverpa zea in the US.

Background: Practical resistance of Helicoverpa zea to Cry proteins has become widespread in the US, making Vip3Aa the only effective Bacillus thuringiensis (Bt) protein for controlling this pest. Understanding the genetic basis of Vip3Aa resistance in H. zea is essential in sustaining the long-term efficacy of Vip3Aa.

Exposure to Cry1 Toxins Increases Long Flight Tendency in Susceptible but Not in Cry1F-Resistant Female (Lepidoptera: Noctuidae).

The fall armyworm (JE Smith) () is a polyphagous pest targeted by selected Cry and Vip3A insecticidal proteins from the bacterium (Bt) that are produced in transgenic Bt corn and cotton. Available evidence suggests that sublethal larval exposure to Cry1Ac increases flight activity in adult spp. However, it is not known whether this effect is also observed in survivors from generally lethal exposure to Cry1Ac.

Synergism of Cry1Ca toxicity by gut resident Enterococcus spp. in the rice stem borer, Chilo suppressalis.

The bacterium Bacillus thuringiensis (Bt) is the most economically successful biopesticide to date, and Bt insecticidal proteins are produced in transgenic crops for pest control. However, relevant details in the Bt-mediated killing process remain undefined. In our previous research, we observed reduced larval susceptibility to Bt Cry1Ca in Chilo suppressalis, a major rice pest in China, after gut microbiota elimination.

Draft genome of neotropical Bacillus thuringiensis UFT038 and its potential against lepidopteran soybean pests.

Bacillus thuringiensis (Bt) is known for its Cry and Vip3A pesticidal proteins with high selectivity to target pests. Here, we assessed the potential of a novel neotropical Bt strain (UFT038) against six lepidopteran pests, including two Cry-resistant populations of fall armyworm, Spodoptera frugiperda. We also sequenced and analyzed the genome of Bt UFT038 to identify genes involved in insecticidal activities or encoding other virulence factors.

Reduced toxin binding associated with resistance to Vip3Aa in the corn earworm ().

is a major crop pest in the United States that is managed with transgenic corn and cotton that produce insecticidal proteins from the bacterium, (Bt). However, has evolved widespread resistance to the Cry proteins produced in Bt corn and cotton, leaving Vip3Aa as the only plant-incorporated protectant in Bt crops that consistently provides excellent control of . The benefits provided by Bt crops will be substantially reduced if widespread Vip3Aa resistance develops in field populations.

Larvae of Colorado potato beetle (Leptinotarsa decemlineata Say) resistant to double-stranded RNA (dsRNA) remain susceptible to small-molecule pesticides.

Background: Implementation of resistance management tools is crucial for the continued efficacy of insect control technologies. An important aspect of insect resistance management (IRM) is the combined or sequential use of different modes-of-action to reduce selection pressure and delay evolution of resistance. This is especially important for insect pests with established ability to develop resistance to insecticides, such as the Colorado potato beetle (Leptinotarsa decemlineata, CPB).

An Extended Investigation of Unexpected (Boddie) Survival and Ear Injury on a Transgenic Maize Hybrid Expressing Cry1A/Cry2A/Vip3A Toxins.

The wide occurrence of resistance to Cry1A and Cry2A insecticidal toxins from () in the corn earworm/bollworm (Boddie) leaves the Vip3A toxin produced during the vegetative stage of as the only fully active toxin expressed in transgenic crops to control in the U.S.A.

Screening for resistance alleles to Cry1 proteins through targeted sequencing in the native and invasive range of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The fall armyworm, Spodoptera frugiperda (J. E. Smith), is a highly polyphagous pest native to the tropical Americas that has recently spread to become a global super-pest threatening food and fiber production.

Lack of fitness costs in dsRNA-resistant Leptinotarsa decemlineata ([Coleoptera]: [Chrysomelidae]).

The Colorado potato beetle, Leptinotarsa decemlineata (Say) ([Coleoptera]: [Chrysomelidae]), is the most important defoliator of solanaceous plants worldwide. This insect displays a notorious ability in adapting to biological and synthetic insecticides, although in some cases this adaptation carries relevant fitness costs. Insecticidal gene silencing by RNA interference is a novel mode of action pesticide against L.

Overexpression of soybean trypsin inhibitor genes decreases defoliation by corn earworm () in soybean () and .

Trypsin inhibitors (TIs) are widely distributed in plants and are known to play a protective role against herbivores. TIs reduce the biological activity of trypsin, an enzyme involved in the breakdown of many different proteins, by inhibiting the activation and catalytic reactions of proteins. Soybean () contains two major TI classes: Kunitz trypsin inhibitor (KTI) and Bowman-Birk inhibitor (BBI).

Hemocyte response to treatment of susceptible and resistant Asian corn borer () larvae with Cry1F toxin from .

Midgut receptors have been recognized as the major mechanism of resistance to Cry proteins in lepidopteran larvae, while there is a dearth of data on the role of hemocyte's response to Cry intoxication and resistance development. We aimed at investigating the role of circulating hemocytes in the intoxication of Cry1F toxin in larvae from susceptible (ACB-BtS) and resistant (ACB-FR) strains of the Asian corn borer (ACB), . Transcriptome and proteome profiling identified genes and proteins involved in immune-related (tetraspanin and C-type lectins) and detoxification pathways as significantly up-regulated in the hemocytes of Cry1F treated ACB-FR.

Evidence of a shared binding site for Bacillus thuringiensis Cry1Ac and Cry2Aa toxins in Cnaphalocrocis medinalis cadherin.

Insect midgut cadherins function as receptors and play critical roles as protein receptors of insecticidal Bacillus thuringiensis (Bt) toxins used as biopesticides and in Bt transgenic crops worldwide. Here, we cloned and characterized the full-length midgut cadherin (CmCad) cDNA from the rice leaffolder (Cnaphalocrocis medinalis), a destructive pest of rice in many Asian countries. Expression of recombinant proteins corresponding to the extracellular domain of CmCad allowed testing binding of Cry proteins.

Novel real-time PCR based assays for differentiating fall armyworm strains using four single nucleotide polymorphisms.

The fall armyworm, is a polyphagous global pest with a preference for gramineous crops such as corn, sorghum and pasture grasses. This species is comprised of two morphologically identical but genetically distinct host strains known as the corn and rice strains, which can complicate pest management approaches. Two molecular markers are commonly used to differentiate between strains, however, discordance between these markers can lead to inconclusive strain identification.

Docking-based generation of antibodies mimicking Cry1A/1B protein binding sites as potential insecticidal agents against diamondback moth (Plutella xylostella).

Background: Broad use of insecticidal Cry proteins from Bacillus thuringiensis in biopesticides and transgenic crops has resulted in cases of practical field resistance, highlighting the need for novel approaches to insect control. Previously we described an anti-Cry1Ab idiotypic-antibody (B12-scFv) displaying toxicity against rice leafroller (Cnaphalocrocis medinalis) larvae, supporting the potential of antibodies for pest control. The goal of the present study was to generate insecticidal antibodies against diamondback moth (Plutella xylostella) larvae.