Insecticidal Activity of Bacillus thuringiensis Proteins against Coleopteran Pests

Abstract

Bacillus thuringiensis is the most successful microbial insecticide agent and its proteins have been studied for many years due to its toxicity against insects mainly belonging to the orders Lepidoptera, Diptera and Coleoptera, which are pests of agro-forestry and medical-veterinary interest. However, studies on the interactions between this bacterium and the insect species classified in the order Coleoptera are more limited when compared to other insect orders. To date, 45 Cry proteins, 2 Cyt proteins, 11 Vip proteins, and 2 Sip proteins have been reported with activity against coleopteran species. A number of these proteins have been successfully used in some insecticidal formulations and in the construction of transgenic crops to provide protection against main beetle pests. In this review, we provide an update on the activity of Bt toxins against coleopteran insects, as well as specific information about the structure and mode of action of coleopteran Bt proteins.

Restoration of susceptibility following removal of selection for Cry34/35Ab1 resistance documents fitness costs in resistant population of western corn rootworm, Diabrotica virgifera virgifera

“…Mortality caused by Cry34/35Ab1 is more likely chronic in nature and relies on a myriad of secondary factors (disease, predation, abiotic stress) 36 . These differences seen in larval susceptibility and the development of resistance to Cry34/35Ab1 could be due to the differences in structure of the binary Cry34/35Ab1 δ‐endotoxin 62 compared to the ternary structure of Cry3Bb1, eCry3.1Ab and mCry3A δ‐endotoxins 63 . The latter three proteins have distinct binding sites, 64–67 and previous studies have shown a lack of cross resistance between Cry34/35Ab1 and other proteins 23 .…”

A major forest insect pest, the pine weevil Hylobius abietis, is more susceptible to Diptera‐ than Coleoptera‐targeted Bacillus thuringiensis strains

“…Although Coleopteran pests are numerous in forest ecosystems, relatively few have been tested for their susceptibility to Bt toxins. Moreover, among studies examining Bt effectiveness against Coleopteran insects, beetles in the family Chrysomelidae are overrepresented while Curculionidae (weevil) species have been less examined 15,16 . A moderate proportion of those Curculionidae species investigated have shown susceptibility to Bt , but few toxins have been tested 15,16 .…”

“…Moreover, among studies examining Bt effectiveness against Coleopteran insects, beetles in the family Chrysomelidae are overrepresented while Curculionidae (weevil) species have been less examined. 15,16 A moderate proportion of those Curculionidae species investigated have shown susceptibility to Bt, but few toxins have been tested. 15,16 The most commonly tested Cry proteins include Cry3Aa (Bt ssp.…”

“…15,16 A moderate proportion of those Curculionidae species investigated have shown susceptibility to Bt, but few toxins have been tested. 15,16 The most commonly tested Cry proteins include Cry3Aa (Bt ssp. tenebrionis) and Cry8Da (Bt ssp.…”

Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action

“…The current knowledge about Vip proteins has also been reviewed [ 2 ], as has the contribution that the use of toxin mutants has made to the knowledge of the mode of action of the three-domain Cry proteins [ 3 ]. On the other hand, two more review papers recapitulate the information on the cytocidal activity of Bt proteins [ 4 ] or the insecticidal activity of Bt proteins against coleopteran pests [ 5 ]. All these review papers are of high value, allowing readers to stay updated on the different aspects of the Bt field described here.…”