Insects 2014, 5(1), 62-91; doi:10.3390/insects5010062
Review

Bacillus thuringiensis Is an Environmental Pathogen and Host-Specificity Has Developed as an Adaptation to Human-Generated Ecological Niches

* email and email
Received: 18 November 2013; in revised form: 3 December 2013 / Accepted: 13 December 2013 / Published: 24 December 2013
(This article belongs to the Special Issue Insect Pathology)
View Full-Text   |   Download PDF [504 KB, uploaded 24 December 2013]
Abstract: Bacillus thuringiensis (Bt) has been used successfully as a biopesticide for more than 60 years. More recently, genes encoding their toxins have been used to transform plants and other organisms. Despite the large amount of research on this bacterium, its true ecology is still a matter of debate, with two major viewpoints dominating: while some understand Bt as an insect pathogen, others see it as a saprophytic bacteria from soil. In this context, Bt’s pathogenicity to other taxa and the possibility that insects may not be the primary targets of Bt are also ideas that further complicate this scenario. The existence of conflicting research results, the difficulty in developing broader ecological and genetics studies, and the great genetic plasticity of this species has cluttered a definitive concept. In this review, we gathered information on the aspects of Bt ecology that are often ignored, in the attempt to clarify the lifestyle, mechanisms of transmission and target host range of this bacterial species. As a result, we propose an integrated view to account for Bt ecology. Although Bt is indeed a pathogenic bacterium that possesses a broad arsenal for virulence and defense mechanisms, as well as a wide range of target hosts, this seems to be an adaptation to specific ecological changes acting on a versatile and cosmopolitan environmental bacterium. Bt pathogenicity and host-specificity was favored evolutionarily by increased populations of certain insect species (or other host animals), whose availability for colonization were mostly caused by anthropogenic activities. These have generated the conditions for ecological imbalances that favored dominance of specific populations of insects, arachnids, nematodes, etc., in certain areas, with narrower genetic backgrounds. These conditions provided the selective pressure for development of new hosts for pathogenic interactions, and so, host specificity of certain strains.
Keywords: Bacillus ecology; multiple hosts; virulence factors; pathogenicity
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Export to BibTeX |
EndNote


MDPI and ACS Style

Argôlo-Filho, R.C.; Loguercio, L.L. Bacillus thuringiensis Is an Environmental Pathogen and Host-Specificity Has Developed as an Adaptation to Human-Generated Ecological Niches. Insects 2014, 5, 62-91.

AMA Style

Argôlo-Filho RC, Loguercio LL. Bacillus thuringiensis Is an Environmental Pathogen and Host-Specificity Has Developed as an Adaptation to Human-Generated Ecological Niches. Insects. 2014; 5(1):62-91.

Chicago/Turabian Style

Argôlo-Filho, Ronaldo C.; Loguercio, Leandro L. 2014. "Bacillus thuringiensis Is an Environmental Pathogen and Host-Specificity Has Developed as an Adaptation to Human-Generated Ecological Niches." Insects 5, no. 1: 62-91.

Insects EISSN 2075-4450 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert