Loss of <i>Bacillus thuringiensis</i> var. <i>israelensis</i> Larvicidal Activity and Its Distribution in Benthic Substrates and Hyporheic Zone of Streams

Tousignant, M. E.; Boisvert, Jonathan; Chalifour, Alain

doi:10.1139/f93-050

Cited by 19 publications

(18 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results indicated that the Bti crystals had been adsorbed by the algae growing on rocks. This interaction was later con® rmed by Tousignant et al (1993) who found that periphyton collected after a Bti treatment (overdosage) was highly toxic to mosquito larvae, but they could not detect any toxic activity associated with sedimented matter.…”

Section: Fate Of Bti Toxic Activity In the Environmentmentioning

confidence: 94%

“…Back et al (1985) showed that two chironomid genera (Diptera) that normally feed on organic debris, and blepharicerid larvae (Diptera) which feed by scraping periphyton growing on rocks, were adversely aVected after a Bti treatment thereby suggesting that Bti toxic crystals were attached to these substrates. Tousignant et al (1993) found that, after treating a small stream with Bti, high percentages of mortality were obtained when periphyton samples were tested against mosquito larvae, indicatin g that Bti toxic particles were associated with this substrate.…”

Section: Factors Avecting Bti Activity Against Black Fliesmentioning

confidence: 99%

“…In a study performed by Tousignant et al (1993) where two streams were treated with Bti, experiments were conducted to monitor the transfer of Bti toxicity from the openchannel water to the underlyin g hyporheic zone. Results showed that Bti toxic crystals were found as deep as 65 cm under the streambed, thus con® rming the exchange of particulate material between the open-channel water and the hyporheic zone, another factor explainin g the loss of Bti in open-channel water.…”

Section: Factors Avecting Bti Activity Against Black Fliesmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Bacillus thuringiensis var. israelensis on Target and Nontarget Organisms: A Review of Laboratory and Field Experiments

Boisvert

2000

Biocontrol Science and Technology

153

145

View full text Add to dashboard Cite

Since the discovery of Bacillus thuringiensi s var. israelensis (Bti) in 1976, extensive literature has proved its eYcacy to control mosquitoes and black Xies, of which many species are known as important vectors of diseases or simply as pests of humans and animals. Since 1978, Bti has been used in many countries on all continents and numerous studies have been made on target mosquitoes and black Xies, as well as nontarget organisms (NTO). This review analyses the results of 75 studies on these organism s covering approximatel y 125 families, 300 genera and 400 species. DiVerent factors such as species, instar, feeding behaviour and environmental parameters (larval density, water temperature, suspended matter etc.) may drastically aVect the eYcacy of the Bti products. This is addressed in detail by reviewing the main factors aVecting mosquitoes as well as black Xies. The results of a wide range of laboratory and Weld experiments using diVerent target and nontarget species, various preparation s and formulations of Bti and diVerent biotic or abiotic factors are present in the literature, making the data diYcult to compare on a common basis. Our analysis shows that, under diVerent application conditions, the eVects of Bti on target and nontarget organism s may be hard to predict. Although Bti has been proclaimed to be relatively highly speciWc, some studies show that some NTO are aVected either by single or repeated Bti treatments. Present use against black Xies seems ecologically acceptable. High frequencies of applicatio n and/or overdosages against mosquitoes may result in some persistence of the toxin crystals and ultimately this may have adverse eVects on the food web. A long-term study (publishe d in 1998) in mosquito habitats has shown that intensive Bti treatments over three years did in fact produce an impact on the food web in wetlands. This raises questions, for the Wrst time, on Bti environmental speciWcity. The importance of this impact is discussed and the alternatives for practical pest control are considered. Some modiWcations of Bti use against mosquitoes, guided by research, is probably the best of these alternatives.

show abstract

Section: Fate Of Bti Toxic Activity In the Environmentmentioning

confidence: 94%

Section: Factors Avecting Bti Activity Against Black Fliesmentioning

confidence: 99%

Section: Factors Avecting Bti Activity Against Black Fliesmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Bacillus thuringiensis var. israelensis on Target and Nontarget Organisms: A Review of Laboratory and Field Experiments

Boisvert

2000

Biocontrol Science and Technology

153

145

View full text Add to dashboard Cite

show abstract

“…First, its insecticidal activity can be tested by performing bioassays using environmental samples (i.e., water, soil, or leaf litter samples, etc.) (9,38,44). Unfortunately, the sensitivity of this approach is often too low to detect slight modifications of toxicity, as B. thuringiensis usually does not exhibit a high level of residual activity (36).…”

mentioning

confidence: 99%

Fate of Bacillus thuringiensis subsp. israelensis in the Field: Evidence for Spore Recycling and Differential Persistence of Toxins in Leaf Litter

Tetreau

Alessi

Veyrenc

et al. 2012

Appl Environ Microbiol

View full text Add to dashboard Cite

Bacillus thuringiensis subsp. israelensis is a bioinsecticide increasingly used worldwide for mosquito control. Despite its apparent low level of persistence in the field due to the rapid loss of its insecticidal activity, an increasing number of studies suggested that the recycling of B. thuringiensis subsp. israelensis can occur under specific, unknown conditions. Decaying leaf litters sampled in mosquito breeding sites in the French Rhône-Alpes region several months after a treatment were shown to exhibit a high level of larval toxicity and contained large amounts of spores. In the present article, we show that the high concentration of toxins found in these litters is consistent with spore recycling in the field, which gave rise to the production of new crystal toxins. Furthermore, in these toxic leaf litter samples, Cry4Aa and Cry4Ba toxins became the major toxins instead of Cyt1Aa in the commercial mixture. In a microcosm experiment performed in the laboratory, we also demonstrated that the toxins, when added in their crystal form to nontoxic leaf litter, exhibited patterns of differential persistence consistent with the proportions of toxins observed in the field-collected toxic leaf litter samples (Cry4 > Cry11 > Cyt). These results give strong evidence that B. thuringiensis subsp. israelensis recycled in specific breeding sites containing leaf litters, and one would be justified in asking whether mosquitoes can become resistant when exposed to field-persistent B. thuringiensis subsp. israelensis for several generations.

show abstract

“…There are several possible explanations, including entrapment of B.t.i. particles by moss (Tousignant et al 1993), or stagnation in slower pools with a gradual release over time.…”

Section: Resultsmentioning

confidence: 99%

Effects of Bacillus thuringiensis subsp. israelensis ( B.t.i. ) Applications on Invertebrates from Two Streams on Prince Edward Island

1997

Bulletin of Environmental Contamination and Toxicology

View full text Add to dashboard Cite

Efforts to control black fly populations stem from their adverse effects, which include reductions in livestock productivity, pathogen transmittal, and severe restrictions in outdoor recreation and tourist activities. Although chemical larvicides such as DDT, methoxychlor and temephos were used initially (Fredeen 1975, Thompson 1975, Back et al. 1979, the mortality of non-target organisms (Mohsen and Mulla 1982, Fredeen 1983) and the loss of efficacy of through the development of larval resistance (Kurtak 1986) prompted the search for a more suitable agent. Several studies have confirmed the efficacy of Bacillus thuringiensis subsp. israelensis (B.t.i.), serotype H-14, against various species of blackfly larvae , de Moor and Carr 1986, Gibbs et al. 1986, Merritt et al. 1989, Riley and Fusco 1990. B.t.i. is a gram-positive, spore-forming bacterium highly toxic to certain dipteran larvae upon consumption (Federici et al. 1990). Widespread use of B.t.i. has resulted in concern for the potential effects on non-target organisms, particularly chironomids which constitute an important part of the diet of young salmonids (White 1930). Several studies have reported the sensitivity of chironomids to B.t.i. and high concentrations of B.t.i. are often used to eradicate chironomids from lakes and mesocosms (Mulls et al. 1990, Rodcharoen et al. 1991. As a number of streams on Prince Edward Island are treated, with treatments frequently extending from the headwaters to the mouth of the stream, it was decided to determine the concentrations of B.t.i. in the water following two operational applications of B.t.i., and to monitor the potential impact on aquatic invertebrates. MATERIALS AND METHODSTwo streams were examined in 1992. Elliotts is a second order stream, ranging from 2.7 to 4.2 m wide and 15 to 23 cm deep. The substratum was comprised largely of gravel and rocky areas with flat riffle sections. Less than 50% of the stream was overstoried. Lower Tryon is a first order brook with a width of 0.9 to 1.6 m, and a depth of 22 to 36 cm. It was soft bottomed and contained two riffle areas. Overstory was less than 30%. Each stream was treated twice, and in each case the stream was sampled prior to and after treatments over a three-day period.

show abstract

Loss of Bacillus thuringiensis var. israelensis Larvicidal Activity and Its Distribution in Benthic Substrates and Hyporheic Zone of Streams

Cited by 19 publications

References 3 publications

Effects of Bacillus thuringiensis var. israelensis on Target and Nontarget Organisms: A Review of Laboratory and Field Experiments

Effects of Bacillus thuringiensis var. israelensis on Target and Nontarget Organisms: A Review of Laboratory and Field Experiments

Fate of Bacillus thuringiensis subsp. israelensis in the Field: Evidence for Spore Recycling and Differential Persistence of Toxins in Leaf Litter

Effects of Bacillus thuringiensis subsp. israelensis ( B.t.i. ) Applications on Invertebrates from Two Streams on Prince Edward Island

Contact Info

Product

Resources

About