Beyond the spore – past and future developments of Bacillus thuringiensis as a biopesticide

Abstract

Formulated and sporulated cultures of Bacillus thuringiensis (Bt) are widely used as foliar sprays as part of integrated pest management strategies against insect pests of agricultural crops. Although in several cases the presence of the spore has been shown to improve the activity of the product, other Bt‐based insecticides have been developed in which the spore is absent. The most notable of these are transgenic plants expressing just the insect toxin gene from the bacterium. This paper will discuss these developments, and the advantages and disadvantages of having the spore present.

Bioactivities of cry gene positive Bacillus thuringiensis (Berliner) (Bacillales: Bacillaceae) strains on Ephestia kuehniella Zeller, 1879 and Plodia interpunctella (Hübner, 1813) (Lepidoptera: Pyralidae)

“…Here, we applied spore and crystal mixtures to stored product pests during bioassays because the mixture is more effective on mortality compared to crystals or spores alone (Crickmore, 2006). The highest toxicity value of four strains changed between 30-42% for E. kuehniella larvae while two strains exhibited 53-63% toxicity to P. interpunctella larvae at a spore-crystal concentration of 500 ppm.…”

Induced-feeding bioassays for detection of Bacillus thuringiensis insecticidal activity against Epilachna paenulata (Coleoptera)

“…This bacterium is characterized by the production, during sporulation, of parasporal crystals composed of insecticidal proteins (Cry), which are biodegradable, highly specific to target insects, and safe for humans, other vertebrates, and for plants (Crickmore, 2006;Sauka & Benintende, 2008). Additionally, the proteinaceous toxins produced by this bacterium are widely used in genetically modification of plants in order to obtain insect-resistant varieties (Sauka & Benintende, 2008).…”

Quick isolation and characterization of novel Bacillus<br>thuringiensis strains from mosquito breeding sites in Malaysia

“…Endotoxins produced by Bacillus species are often species specific and they do not contaminate the environment as the toxins have lesser residual efficacy and are generally safe for non-target organisms (Lacey and Undeen, 1986;Siegel, 2001;Moraga et al, 2004;Crickmore, 2006). This is due to the presence of insecticidal crystal proteins (ICP) which are biodegradable and environmental friendly (Ibarra et al, 2003).…”

“…This includes natural enemies such as parasites and pollinators like honey bees Federici, 2005). Thus, B. thuringiensis integrates well with other biological controls (Crickmore, 2006). Since B. thuringiensis is host specific, it is non toxic to humans and animals if they happened to be exposed to it (Siegel, 2001).…”