Bacillus thuringiensis var. israelensis (Bti) Provides Residual Control of Aedes aegypti in Small Containers

Ritchie, Scott A.; Rapley, Luke P.; Benjamin, Seleena

doi:10.4269/ajtmh.2010.09-0603

Cited by 51 publications

(39 citation statements)

References 15 publications

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“…After misting, the test cups were left undisturbed for 30 minutes before being fitted with a lid and collected. They were placed in respective treatment crates covered with mosquito-proof mesh similar to that used by Ritchie and others (2010) and transported 17 to a shaded outdoor area that was exposed to rainfall. This placement enabled controlled conditions for rearing, thus, reducing the influence of random environmental effects to the study.…”

Section: Methodsmentioning

confidence: 99%

“…israelensis (Bti) is an established microbial agent that kills mosquito larvae when ingested. 17,18 It is target-specific, free from bacterial contaminants and exotoxins, safe for drinking water, and poses no significant hazards to the environment. 14,19 Furthermore, it is effective against dengue vectors in village, urban, and suburban environs, and it has recently been reported as reducing dengue cases and vector numbers.…”

Section: Introductionmentioning

confidence: 99%

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Bacillus thuringiensis var. israelensis Misting for Control of Aedes in Cryptic Ground Containers in North Queensland, Australia

Jacups

Rapley²,

Johnson³

et al. 2013

The American Society of Tropical Medicine and Hygiene

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Abstract. In Australia, dengue is not endemic, although the vector mosquito Aedes aegypti is established in far north Queensland (FNQ). Aedes albopictus has recently invaded the Torres Strait region, but is not established on mainland Australia. To maintain dengue-free, public health departments in FNQ closely monitor introduced dengue infections and confine outbreaks through rigorous vector control responses. To safeguard mainland Australia from Ae. albopictus establishment, pre-emptive strategies are required to reduce its breeding in difficult to access habitats. We compare the residual efficacy of VectoBac WDG, Bacillus thuringiensis var. israelensis (Bti) formulation, as a residual treatment when misted across a typical FNQ bushland using a backpack mister (Stihl SR 420 Mist Blower) at two dose rates up to 16 m. Semi-field condition results, over 16 weeks, indicate that Bti provided high mortality rates ( 80%) sustained for 11 weeks. Mist application penetrated 16 m of dense bushland without efficacy decline over distance.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bacillus thuringiensis var. israelensis Misting for Control of Aedes in Cryptic Ground Containers in North Queensland, Australia

Jacups

Rapley²,

Johnson³

et al. 2013

The American Society of Tropical Medicine and Hygiene

Self Cite

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“…Therefore, the application of larvicides to kill all immature stages during an outbreak remains an important issue. A study to increase the residual effect of Bti in small temporary containers is warranted and recommended (13). Furthermore, the dengue viruses persist in viremic patients during an outbreak; therefore, it is also critical to decrease the risk of female mosquitoes becoming infectious females by killing the pupae.…”

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confidence: 99%

Efficacy of Various Larvicides against <i>Aedes aegypti</i> Immatures in the Laboratory

et al. 2013

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SUMMARY:We conducted a laboratory study to evaluate the efficacy of control agents against small larvae, large larvae, and pupae of Aedes aegypti to determine an appropriate larvicide regime to employ in emergency dengue control programs. The control agents included Bacillus thuringiensis var. israelensis (Bti), pyriproxyfen (an insect growth regulator), a larvicidal oil, Aquatain AMF (polydimethylsiloxane, a monomolecular film), and temephos at the recommend application dosages and rates. Our results showed that Bti, pyriproxyfen, and temephos were efficacious (100z mortality) against larvae, irrespective of the instar stage, but not against pupae of Ae. aegypti (1.5-7.8z mortality). Aquatain AMF, on the other hand, was very effective at controlling the pupal stage (100z mortality), but had limited efficacy against small larvae (38.0z mortality) and large larvae (78.0z mortality). The larvicidal oil was effective against all immature stages (93.3-100z mortality). Therefore, we concluded that for effectively interrupting the dengue transmission cycle, larvicides that kill the pupal stage (Aquatain AMF or larvicidal oil) should be included in an emergency dengue control program in addition to Bti, pyriproxyfen, or temephos.In Taiwan, dengue fever is considered a travel-related disease because the causative viruses are introduced in the early summer by travelers from dengue-endemic countries (1,2). These viruses are subsequently passed to local dengue vectors and then transmitted to local human populations, resulting in small to medium-sized outbreaks. Proactive and emergency strategies (source reduction and the use of insecticide sprays) to control dengue outbreaks have been launched each year for the past decade in Taiwan. The principal methods include the application of adulticides, removal of small containers, the application of larvicides to stagnant water, and the release of mosquito-eating fish such as Macropodus opercularis Ahl and Poecilia reticulata Peters.The most commonly used larvicides to control Aedes aegypti L. worldwide include Bacillus thuringiensis var. israelensis (Bti), pyriproxyfen (an insect growth regulator), temephos (an organophosphate), larvicidal oils, and Aquatain anti-mosquito film (AMF; a monomolecular film) (3,4). These larvicides kill immature stages of mosquitoes through different mechanisms. For example, one such mechanism is larval poisoning over a short duration, with a toxin, such as Bti and temephos, which kill all Ae. aegypti larvae within 24 h (5). A second mechanism is to delay larval development and prevent the emergence of adults. For example, the sand formulation of pyriproxyfen caused 100z mortality in larvae and pupae at 0.2 ppm (5). A third mechanism is physical, as illustrated by Aquatain AMF and larvicidal oils that spread across the water surface and form a very thin film that suffocates larvae and pupae (6). Aquatain AMF treatment (1 mL/m 2 ) causes 48z mortality of Ae. aegypti larvae after 48 h of exposure and 100z mortality of pupae after 3 h of exposure in the...

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“…israelensis residual activity in many different conditions, including rivers, lotic zones, benthic zones (1, 2, 39), saltmarshes (8), and water tanks and containers (6,34). It was shown that this residual activity ranged from a few days to several months, and many environmental factors (e.g., UV light, temperature, etc.)…”

Section: Discussionmentioning

confidence: 99%

Decreased Toxicity of Bacillus thuringiensis subsp. israelensis to Mosquito Larvae after Contact with Leaf Litter

Tetreau

Stalinski

Kersusan

et al. 2012

Appl Environ Microbiol

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Bacillus thuringiensis subsp. israelensis is a bacterium producing crystals containing Cry and Cyt proteins, which are toxic for mosquito larvae. Nothing is known about the interaction between crystal toxins and decaying leaf litter, which is a major component of several mosquito breeding sites and represents an important food source. In the present work, we investigated the behavior of B. thuringiensis subsp. israelensis toxic crystals sprayed on leaf litter. In the presence of leaf litter, a 60% decrease in the amount of Cyt toxin detectable by immunology (enzyme-linked immunosorbent assays [ELISAs]) was observed, while the respective proportions of Cry toxins were not affected. The toxicity of Cry toxins toward Aedes aegypti larvae was not affected by leaf litter, while the synergistic effect of Cyt toxins on all B. thuringiensis subsp. israelensis Cry toxins was decreased by about 20% when mixed with leaf litter. The toxicity of two commercial B. thuringiensis subsp. israelensis strains (VectoBac WG and VectoBac 12AS) and a laboratory-produced B. thuringiensis subsp. israelensis strain decreased by about 70% when mixed with leaf litter. Taken together, these results suggest that Cyt toxins interact with leaf litter, resulting in a decreased toxicity of B. thuringiensis subsp. israelensis in litter-rich environments and thereby dramatically reducing the efficiency of mosquitocidal treatments.

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Bacillus thuringiensis var. israelensis (Bti) Provides Residual Control of Aedes aegypti in Small Containers

Cited by 51 publications

References 15 publications

Bacillus thuringiensis var. israelensis Misting for Control of Aedes in Cryptic Ground Containers in North Queensland, Australia

Bacillus thuringiensis var. israelensis Misting for Control of Aedes in Cryptic Ground Containers in North Queensland, Australia

Efficacy of Various Larvicides against <i>Aedes aegypti</i> Immatures in the Laboratory

Decreased Toxicity of Bacillus thuringiensis subsp. israelensis to Mosquito Larvae after Contact with Leaf Litter

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