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

Abstract

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.

Microbial larvicides for mosquito control: Impact of long lasting formulations ofBacillus thuringiensisvar.israelensisandBacillus sphaericuson non‐target organisms in western Kenya highlands

“…Of particular relevance, no study has so far reported any direct significant effect of Bti and Bs to the organisms monitored in the current study. Significant adverse effects have been observed in certain dipterans when exposed to Bti, as summarized in a review by Boisvert (Boisvert & Boisvert, 2000). However, in most of these cases, treatments were either overdosed or the adverse effects were linked to other factors such as formulation additives, turbidity or methodological errors (Boisvert & Boisvert, 2000).…”

“…It has previously been reported that lentic organisms are particularly more exposed to Bti and Bs than lotic organisms due to heavier accumulation of toxin in the former than the later ecosystem (Boisvert & Boisvert, 2000). With mosquito larval habitats being of the lentic ecosystem, there may be a possibility of accumulation of Bti and Bs toxins to levels that can impact non‐target organisms.…”

“…However, the observation that Bti toxic crystals may persist in the environment has raised some concern that intensive applications could lead to accumulation of toxins with adverse effect on non‐target organisms (Boisvert & Boisvert, 1999; Dupont & Boisvert, 1986; Paris et al., 2011; Tilquin et al., 2008). An extensive review of the effect Bti on target and non‐target organisms has listed a number of studies indicating some negative effects on non‐target organisms (Boisvert & Boisvert, 2000). Other studies have suggested that by removing the target organisms, an important segment of the food web is removed, thereby possibly reducing ecosystem diversity and potentially altering the overall community structure (Hershey, Lima, Niemi, & Regal, 1998; Merritt, Wipfli, & Wotton, 1991).…”

Corrigendum: Does mosquito control by Bti spraying affect the phytoplankton community? A 5-year study in Camargue temporary wetlands (France)

“…Living near wetlands often entails serious health hazards for humans and animals due to increased risk of mosquito-borne diseases (Russell, 1999;Walton, 2002;Kirkman et al, 2011;Lagadic et al, 2014). To date, Bti represents the best alternative to chemical insecticides for mosquito control (Despre´s et al, 2011) and is described as non-toxic to humans, mammals, birds, fish, plants and most aquatic organisms (Boisvert and Boisvert, 2000;Lacey and Merritt, 2004). Bti is the only larvicide used in Europe following implementation of the EU Biocidal Products Directive 98/8/EC (Lagadic et al, 2014).…”

Ce que le moustique nous apprend sur le dualisme anthropocentrisme/biocentrisme : perspective interdisciplinaire sociologie/biologie

“…Les molécules à large spectre d'action ont ainsi progressivement cédé la place aux insecticides dits biologiques, comme le Bti (Bacillus thuringiensis var. israëlensis), plus sélectifs avec peu ou pas d'effets néfastes démontrés sur l'environnement (Becker et Margalit, 1993 ;Boisvert et Boisvert, 2000 ;Franquet et al, 2002). Ce bacille agit après ingestion, par des larves de Diptères, en libérant des toxines protéiques qui perforent l'épithélium intestinal et conduisent à leur mort.…”