Aedes aegypti bacillus thuringiensis

As a part of the search for environment-friendly biocontrol of mosquito-borne diseases, mosquito larvicidal potential of Bacillus thuringiensis subsp. jegathesan (Btj) Cry toxins is explored for toxins with increased toxicity. Safe delivery of the Cry toxins to mosquito larvae in aquatic habitats is a major concern. This is because in water bodies Bacillus thuringiensis (Bt) protein formulations degrade by sunlight, can sink down and get adsorbed by the silt. So, because of its short persistence the toxin requires repeated applications at the given site...

Chemical control of vectors depends on the effective application of formulated insecticides. In this study we evaluated formulated larvicides using a larval bioassay against susceptible Aedes aegypti. The estimated larvicide lethal concentrations for 50% mortality (LC50s) were 25.7 μg/liter (Natular 2EC), 3.13 μg/liter (Abate 4E), 0.43 μg/liter (Altosid), 0.03 μg/liter (Nyguard), and 500.6 ITU/liter (VectoBac12AS containing Bacillus thuringiensis israelensis). Sublethal effects were identified and documented from adults that survived exposure to these estimated LC50s (body size and sex proportion)...

Wide-Area Larviciding techniques (WALS™) using aqueous suspensions of Bacillus thuringiensis israelensis and various types of mist sprayers have typically been employed against container-inhabiting species of mosquitoes such as Aedes albopictus and Ae. aegypti in urban peridomestic environments. However, relatively little work has been done to examine the use of WALS-applied aqueous suspensions of Lysinibacillus sphaericus (Ls) against susceptible species of mosquitoes in larger natural habitats such as forest pools, floodwaters, and marshes...

The three-domain Cry4Aa toxin produced from Bacillus thuringiensis subsp. israelensis was previously shown to be much more toxic to Culex mosquito larvae than its closely related toxin-Cry4Ba. The interaction of these two individual toxins with target receptors on susceptible larval midgut cells is likely to be the critical determinant in their differential toxicity. Here, two full-length membrane-bound alkaline phosphatase (mALP) isoforms from Culex quinquefasciatus larvae, Cq- mALP1263and Cq- mALP1264, predicted to be GPI-linked was cloned and functionally expressed in Spodoptera frugiperda ( Sf 9) cells as 57- and 61-kDa membrane-bound proteins, respectively...

The current investigation describes the isolation and characterization of toxic Bt . local isolates harboring 99% homology with Bti. prototoxin Bacillus thuringiensis (AXJ97553.1 and novel OUB27301.1) which contains full length cry11 gene (1.9 kb). Initially, it was cloned in pTZ57R/T and then sub-cloned in pET30a(+) for expression. The optimized conditions for good expression were found 1 mM IPTG, 3.5-4 h incubation time, and 37 °C. Toxicological assays were determined against 3rd instar larvae of Aedes aegypti with expressed partially purified and crude recombinant protein using recombinant E...

Bacillus thuringiensis (Bt) isolates native to Maranhão (BtMA) that are highly toxic to Aedes aegypti larvae and seven standard subspecies of Bt were analyzed for genetic diversity using the rep-PRC technique with BOX, ERIC, REP, MB1, and GTG5 markers. The rep-PCR technique is considered an extremely reliable, reproducible, fast and highly discriminatory technique that may be used even among populations of the same species. These five markers revealed a total of 38 polymorphic DNA fragments for 30 BtMA isolates...

Mist sprayers (MS) are being rapidly adopted nationwide for applying larvicides to control peridomestic Aedes aegypti. Because MS can loft large quantities of larvicide over relatively long distances, we examined its efficacy in a tidal marsh habitat for controlling Ae. dorsalis. Liquid Vectobac 12AS larvicide, containing Bacillus thuringiensis israelensis, was applied at 1.16 liter/ha using a MS. Cards that change color when exposed to liquid were placed perpendicular to the path of the MS showed that the larvicide mist traveled up to 60 m from the MS and did not extend to 90 m...

Silver/silver chloride nanoparticles (Ag/AgCl NPs) are an alternative approach to control the larvae of Aedes aegypti , a vector of mosquito-borne diseases. However, the molecular mechanisms of Ag/AgCl NPs to A. aegypti have not been reported. In this work, Ag/AgCl NPs were synthesized using supernatant, mixed toxins from Bacillus thuringiensis subsp. israelensis ( Bti ), and heterologously expressed Cry4Aa and Cry4Ba toxins. The images from scanning electron microscopy revealed that the Ag/AgCl NPs were spherical in shape with a size range of 25-100 nm...

Aedes aegypti is a crucial vector for many arboviral diseases that cause millions of deaths worldwide and thus is of major public health concern. Crystal (Cry) proteins, which are toxins produced by Bacillus thuringiensis , are structurally organized into three-domains, of which domain II is the most variable in terms of binding towards various toxin receptors. The binding of Cry11Aa to putative receptor such as aminopeptidase-N (APN) is explicitly inhibited by midgut C-type lectins (CTLs). The similarity between the domain II fold of Cry11Aa toxin and the carbohydrate recognition domain in the CTLs is a possible structural basis for the involvement of Cry domain II in the recognition of carbohydrates on toxin receptors...

High-level expression of transgenes in the chloroplast of wild-type Chlamydomonas reinhardtii ( C. reinhardtii ) remains challenging for many genes (e.g., the cry toxin genes from Bacillus thuringiensis israelensis ). The bottleneck is presumed to be post-transcriptional and mediated by the 5' element and the coding region. Using 5' elements from highly expressed photosynthesis genes such as atpA did not improve the outcome with cry11A regardless of the promoter. However, when we employed the 5' UTR from mature   rps4 mRNA with clean fusions to promoters, production of the rCry11A protein became largely promoter-dependent...

Bacterial larvicides Bacillus thuringiensis var. israelensis ( Bti ) and Bacillus sphaericus ( Bs ) have been used extensively for mosquito control. However, their efficacy varies greatly mainly due to factors related to target mosquitoes, larval habitat conditions, and inherent larvicide properties. We evaluated the efficacy of Bti (Bactivec®) and Bs (Griselesf®) for control of Anopheles gambiae complex, Culex quinquefasciatus and Aedes aegypti larvae under laboratory and semi-field conditions in northeastern Tanzania...

Aedes aegypti is one of the world's most dangerous mosquitoes, and a vector of diseases such as dengue fever, chikungunya virus, yellow fever, and Zika virus disease. Currently, a major global challenge is the scarcity of antiviral medicine and vaccine for arboviruses. Bacillus thuringiensis var israelensis ( Bti ) toxins are used as biological mosquito control agents. Endotoxins, including Cry4Aa, Cry4Ba, Cry10Aa, Cry11Aa, and Cyt1Aa, are toxic to mosquitoes. Insect eradication by Cry toxin relies primarily on the interaction of cry toxins with key toxin receptors, such as aminopeptidase (APN), alkaline phosphatase (ALP), cadherin (CAD), and ATP-binding cassette transporters...

Insect immune responses to multiple pathogen groups including viruses, bacteria, fungi, and entomopathogenic nematodes have traditionally been documented in model insects such as Drosophila melanogaster, or medically important insects such as Aedes aegypti. Despite their potential importance in understanding the efficacy of pathogens as biological control agents, these responses are infrequently studied in agriculturally important pests. Additionally, studies that investigate responses of a host species to different pathogen groups are uncommon, and typically focus on only a single time point during infection...

BACKGROUND: Dengue fever is a major public health concern in Cambodia, with thousands of cases every year in urban, suburban and rural areas of the country. The main vector of dengue fever in Cambodia is Aedes aegypti. The organophosphate larvicide temephos and adulticides belonging to the pyrethroid family have been widely used for decades by public health authorities to fight dengue vectors, but resistance of Ae. aegypti to these insecticides has been previously described for Cambodia...

Since 2011, the Florida Keys Mosquito Control District (FKMCD) has used the WALS® application strategy with VectoBac® WDG containing Bacillus thuringiensis israelensis via helicopter in Key West for the control of Aedes aegypti larval populations. In 2018, FKMCD conducted a study to determine the effectiveness of using a trailer-mounted A1 Super Duty Mist Sprayer® (A1 Mist Sprayers) with a Micronair® AU5000 (Micron Group) atomizer to apply VectoBac WDG by ground at the rate of 0.5 lb/acre (0.56 kg/ha). Bioassay cups were placed in a residential area encompassing open, moderate, and heavy cover scenarios between 0 and 300 ft (0-91...

Bacillus thuringiensis subsp. israelensis (Bti) spherical parasporal crystal contains several insecticidal proteins used as environmentally safe alternative to toxic chemical pesticides. The exploration of a Bti strain isolated from Qatar QBT220 genes encoding the δ-endotoxins responsible of the insecticidal activities revealed the alteration of a 14-kb DNA region including the δ-endotoxins cry10A and cyt1C genes of pBtoxis plasmid. The presence of all the insecticidal genes except cry10A and cyt1C was explained by a structural instability of the plasmid pBtoxis...

Bacillus thuringiensis is the most successful microbial insecticide against different pests in agriculture and vectors of diseases. Its activity is mostly attributed to the Cry proteins expressed during its sporulation phase. However, these proteins are not exclusive to B. thuringiensis. Some cry genes have been found in other Bacillus species, or even in other genera. In this work, cry genes were searched in 223 acrystalliferous bacillaceous strains. From these strains 13 amplicons were obtained, cloned, and sequenced; however, only 6 amplicons tested positive for cry-like genes, and the 6 isolates showed to be the same strain...

In addition to the receptor-binding domain (DII), the C-terminal domain (DIII) of three-domain Cry insecticidal δ-endotoxins from Bacillus thuringiensis has been implicated in target insect specificity, yet its precise mechanistic role remains unclear. Here, the 21 kDa high-purity isolated DIII fragment derived from the Cry4Ba mosquito-specific toxin was achieved via optimized preparative FPLC, allowing direct rendering analyses for binding characteristics toward its target receptor- Aedes aegypti membrane-bound alkaline phosphatase (Aa-mALP)...

Some Bacillus thuringiensis (Bt) strains produce dipteran-active toxins and can control larval mosquitoes. We identified a novel mosquitocidal toxin named Xpp81Aa1 with the thioredoxin domain from Bt strain HSY204. This toxin has very little sequence similarity to the three-domain Cry toxin and Cyt toxins and has significant toxicity to Aedes aegypti larvae. A safety assessment indicated that the Xpp81Aa1 toxin has no cytocidal activity against red blood cells and did not induce allergic reactions. The Xpp81Aa1 toxin exhibited a synergistic effect in combination with Cry2Aa and Cry4Aa protein toxins...

BACKGROUND: Aedes aegypti can transmit arboviruses worldwide, and Bacillus thuringiensis svar. israelensis (Bti)-based larvicides represent an effective tool for controlling this species. The safety of Bti and lack of resistance have been widely reported; however, little is known regarding the impact of the extensive use of these larvicides on the life traits of mosquitoes. Therefore, this study investigated biological parameters, including susceptibility to arbovirus, of an Ae. aegypti strain (RecBti) subjected to 29 generations of exposure to Bti compared with the RecL reference strain...