Evolution and the microbial control of insects

Abstract

Insect pathogens can be utilized in a variety of pest management approaches, from inundative release to augmentation and classical biological control, and microevolution and the consideration of evolutionary principles can potentially influence the success of all these strategies. Considerable diversity exists in natural entomopathogen populations and this diversity can be either beneficial or detrimental for pest suppression, depending on the pathogen and its mode of competition, and this should be considered in the selection of isolates for biological control. Target hosts can exhibit considerable variation in their susceptibility to entomopathogens, and cases of field-evolved resistance have been documented for Bacillus thuringiensis and baculoviruses. Strong selection, limited pathogen diversity, reduced gene flow, and host plant chemistry are linked to cases of resistance and should be considered when developing resistance management strategies. Pre- and post-release monitoring of microbial control programs have received little attention; however, to date there have been no reports of host-range evolution or long-term negative effects on nontarget hosts. Comparative analyses of pathogen population structure, virulence, and host resistance over time are required to elucidate the evolutionary dynamics of microbial control systems.

Identification of Spodoptera exigua nucleopolyhedrovirus genes involved in pathogenicity and virulence

“…Viruses undergo evolution by gene loss or gain, gene exchange and by accumulation of point mutations that can lead to specialization in gene function (Garavaglia et al, 2012). Evolutionary variation in entomopathogenic populations could benefit selection of variants with an enhanced level of a particular trait, that can be useful when these pathogens are used as a microbial control agent (Cory and Franklin, 2012).…”

Ecology and evolution of pathogens in natural populations of Lepidoptera

“…). The mechanism by which this occurs remains to be elucidated; however; it could have major implications for both practical pest management and the evolution of resistance (Cory and Franklin ).…”

Promise for plant pest control: root-associated pseudomonads with insecticidal activities

“…However, the major drawback of this new biotechnology has been the development of resistance against the Cry toxins by pests (Bravo et al, 2011). Due to the relatively simple mode of action of Cry toxins and the absence of complementary virulence factors normally found in the complete microorganism, resistance is much more probable to develop toward the insect toxin in the GM plants than to the entire microorganism (Cory and Franklin, 2012). Infections by microbial pathogens are complex and likely to require more diverse polygenic resistance mechanisms in pest insects.…”