Insect toxin

BACKGROUND: Despite their known negative effects on ecosystems and human health, synthetic pesticides are still largely used to control crop insect pests. Actually, the biopesticide market for insect biocontrol mainly relies on the entomopathogenic bacterium Bacillus thuringiensis (Bt). New biocontrol tools for crop protection might derive from fungi, in particular from Trichoderma spp., which are known producers of chitinases and other bioactive compounds able to negatively affect insect survival...

In their natural habitat, insects may bioaccumulate toxins from plants for defence against predators. When insects are accidently raised on feed that is contaminated with toxins from co-harvested herbs, this may pose a health risk when used for human or animal consumption. Plant toxins of particular relevance are the pyrrolizidine alkaloids (PAs), which are genotoxic carcinogens produced by a wide variety of plant species and the tropane alkaloids (TAs) which are produced by a number of Solanaceae species. This study aimed to investigate the transfer of these plant toxins from substrates to black soldier fly larvae (BSFL) and lesser mealworm (LMW)...

Entomopathogenic nematodes from the genus Steinernema (Nematoda: Steinernematidae) are capable of causing the rapid killing of insect hosts, facilitated by their association with symbiotic Gram-negative bacteria in the genus Xenorhabdus (Enterobacterales: Morganellaceae), positioning them as interesting candidate tools for the control of insect pests. In spite of this, only a limited number of species from this bacterial genus have been identified from their nematode hosts and their insecticidal properties documented...

Paralipsa gularis (Zeller) is a storage pest; however, in recent years it has evolved into a considerable maize pest during the late growth stage in the border region between China and other Southeast Asian countries. Bt transgenic insect-resistant maize is an effective measure in controlling a wide range of lepidopteran pests, but there is a lack of research on the toxic effects of storage pests. We tested the toxicity of Bt-Cry1Ab, Vip3Aa, and their complex proteins against P. gularis via bioassay and investigated the efficiency of Bt-(Cry1Ab+Vip3Aa) maize in controlling P...

Fusarium fungi produce a diverse array of mycotoxic metabolites during the pathogenesis of cereals. Some, such as the trichothecenes and fumonisins, are phytotoxic, acting as non-proteinaceous effectors that facilitate disease development in cereals. Over the last few decades, we have gained some depth of understanding as to how trichothecenes and fumonisins interact with plant cells and how plants deploy mycotoxin detoxification and resistance strategies to defend themselves against the producer fungi. The cereal-mycotoxin interaction is part of a co-evolutionary dance between Fusarium and cereals, as evidenced by a trichothecene-responsive, taxonomically restricted, cereal gene competing with a fungal effector protein and enhancing tolerance to the trichothecene and resistance to DON-producing F...

Plants store chemical defenses that act as toxins against herbivores, such as toxic isothiocyanates (ITCs) in Brassica plants, hydrolyzed from glucosinolate (GLS) precursors. The fitness of herbivorous larvae can be strongly affected by these toxins, causing immature death. We modeled this phenomenon using a set of ordinary differential equations and established a direct relationship between feeding, toxin exposure, and the net energy of a larva, where the fitness of an organism is proportional to its net energy according to optimal foraging theory...

Understanding the often antagonistic plant-herbivore interactions and how host defenses can influence herbivore dietary breadth is an area of ongoing study in ecology and evolutionary biology. Typically, host plants/fungi that produce highly noxious chemical defenses are only fed on by specialists. We know very little about generalist species that can feed and develop on a noxious host. One such example of generalists feeding on toxic host occurs in the mushroom-feeding Drosophila found in the immigrans-tripunctata radiation...

BACKGROUND: With the increasing incidence of pest resistance to transgenic crops producing Bacillus thuringiensis (Bt) proteins in the field, elucidating the molecular basis of resistance is important for monitoring, delaying, and countering pest resistance. Previous work revealed that mutation or downregulated expression of the cadherin gene (PgCad1) is associated with pink bollworm (Pectinophora gossypiella) resistance to Cry1Ac, and twenty mutant PgCad1 alleles (r1-r20) were characterized...

Overuse of insecticides has accelerated the evolution of insecticide resistance and created serious environmental concerns worldwide, thus incentivizing development of alternative methods. Bacillus thuringiensis (Bt) is an insecticidal bacterium that has been developed as a biopesticide to successfully control multiple species of pests. It operates by secreting several insect toxins such as Cry1Ac. However, metabolic resistance based on ATP-binding cassette (ABC) transporters may play a crucial role in the development of metabolic resistance to Bt...

Pseudomonas aeruginosa is one of the most versatile bacteria with renowned pathogenicity and extensive drug resistance. The diverse habitats of this bacterium include fresh, saline and drainage waters, soil, moist surfaces, taps, showerheads, pipelines, medical implants, nematodes, insects, plants, animals, birds and humans. The arsenal of virulence factors produced by P. aeruginosa includes pyocyanin, rhamnolipids, siderophores, lytic enzymes, toxins and polysaccharides. All these virulent elements coupled with intrinsic, adaptive and acquired antibiotic resistance facilitate persistent colonization and lethal infections in different hosts...

Chrysomya albiceps (Calliphoridae) is among the earliest successional fauna on human and animal cadavers. Some immature Calliphoridae can be useful for determination of post-mortem interval. Toxins, particularly pesticides, can affect the rate of insect growth. Aluminum phosphide (AlP) is an affordable insecticide that has not been adequately entomotoxicologically evaluated. So, the impact of AlP on the developmental rate of different stages of C. albiceps was investigated. Larvae of C. albiceps were reared on the rabbit carcasses containing AlP as a treated group, and distilled water as a control group...

BACKGROUND: Bacillus thuringiensis (Bt) and its crystal toxin or δ-endotoxins (Cry) offer great potential for the efficient control of crop pests. A vast number of pests can potentially infect the same host plant, either simultaneously or sequentially. However, no effective Bt-Cry protein has been reported to control both aphids and plant parasitic nematodes due to its highly specific activity. RESULTS: Our study indicated that the Cry5Ba2 protein was toxic to the green peach aphid Myzus persicae, which had an LC50 of 9...

The evolutionary dynamics of large gene families can offer important insights into the functions of their individual members. While the ecdysteroid kinase-like (EcKL) gene family has previously been linked to the metabolism of both steroid moulting hormones and xenobiotic toxins, the functions of nearly all EcKL genes are unknown and there is little information on their evolution across all insects. Here, we perform comprehensive phylogenetic analyses on a manually annotated set of EcKL genes from 140 insect genomes, revealing the gene family is comprised of at least 13 subfamilies that differ in retention and stability...

The extracellular signal-regulated kinase (ERK) pathway, a critical genetic determinant, controls diverse physiological functions, including innate immunity, development, and stress response. In the current study, a full-length cDNA (1592bp) encoding the ERK gene (OfERK) was cloned from Ostrinia furnacalis Guenée (GenBank accession number: MF797866). The open reading frame of the OfERK gene encoded 364 amino acids and shared 96.43%-98.08% amino acid identities with other insect mitogen-activated protein kinases...

The endosymbiotic bacteria Wolbachia can invade insect populations by modifying host reproduction through cytoplasmic incompatibility (CI), an effect that results in embryonic lethality when Wolbachia-carrying males mate with Wolbachia-free females. Here we describe a transgenic system for recreating CI in the major arbovirus vector Aedes aegypti using CI factor (cif) genes from wAlbB, a Wolbachia strain currently being deployed to reduce dengue transmission. CI-like sterility is induced when cifA and cifB are co-expressed in testes; this sterility is rescued by maternal cifA expression, thereby reproducing the pattern of Wolbachia-induced CI...

Bacillus thuringiensis is a Gram-positive bacterium known for its insecticidal proteins effective against various insect pests. However, limited strains and proteins target coleopteran pests like Anthonomous grandis Boheman, causing substantial economic losses in the cotton industry. This study focuses on characterizing a Bacillus sp. strain, isolated from Oncativo (Argentina), which exhibits ovoid to amorphous parasporal crystals and was designated Bt_UNVM-84. Its genome encodes genes for the production of two pairs of binary Vpb1/Vpa2 proteins and three Cry-like proteins showing similarity with different Cry8 proteins...

Bt soybean cultivation is increasing worldwide. The Cry1Ac protein expressed in Bt soybean efficiently controls several lepidopteran pests. The stink bug, Piezodorus guildinii (Westwood), a major pest for soybean in the Americas, is not controlled by Bt crops, although possible sub-lethal effects may occur. Even if there were no negative effects for sting bug, ingesting toxins could affect its bio-controllers. We tested through ELISA detection if P. guildinii ingests Cry1Ac from Bt soybean and possible effects on its development, reproduction, survival, and feeding behavior...

BACKGROUND: Hereditary alpha-tryptasemia (HAT) is a genetic predisposition of autosomal dominant inheritance that leads to a high normal (≥ 8-11.4 μg/L) or pathologically elevated (>11.4 μg/L) basal serum tryptase (BST) concentration. Its prevalence in the United Kingdom and France is reportedly 5%-6%; its prevalence in Germany is unknown. Symptomatic persons with HAT suffer from a complex constellation of symptoms. As described in this review, HAT is an important differential diagnosis in interdisciplinary practice...

Xenorhabdus and Photorhabdus, bacterial symbionts of entomopathogenic nematodes Steinernema and Heterorhabditis , respectively, have several biological activities including insecticidal and antimicrobial activities. Thus, XnChi, XhChi, and PtChi, chitinases of X. nematophila , X. hominickii , and P. temperata isolated from Korean indigenous EPNs S. carpocapsae GJ1-2, S. monticolum GJ11-1, and H. megidis GJ1-2 were cloned and expressed in Escherichia coli BL21 to compare their biological activities. Chitinase proteins of these bacterial symbionts purified using the Ni-NTA system showed different chitobiosidase and endochitinase activities, but N-acetylglucosamidinase activities were not shown in the measuring of chitinolytic activity through N-acetyl-D-glucosarmine oligomers...

The fall armyworm (JE Smith) ( Spodoptera frugiperda ) is a polyphagous pest targeted by selected Cry and Vip3A insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) that are produced in transgenic Bt corn and cotton. Available evidence suggests that sublethal larval exposure to Cry1Ac increases flight activity in adult Spodoptera spp. However, it is not known whether this effect is also observed in survivors from generally lethal exposure to Cry1Ac. Moreover, while multiple cases of field-evolved resistance to Bt proteins have been described in the native range of S...