Characterization of the synergistic interaction between Beauveria bassiana strain GHA and Bacillus thuringiensis morrisoni strain tenebrionis applied against Colorado potato beetle larvae

Abstract

Please cite this article as: Wraight, S.P., Ramos, M.E., Characterization of the synergistic interaction between Beauveria bassiana strain GHA and Bacillus thuringiensis morrisoni strain tenebrionis applied against Colorado potato beetle larvae, Journal of Invertebrate Pathology (2017), doi: http://dx.doi.org/10. 1016/j.jip.2017.01.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. • Results indicated synergism of B. bassiana activity by B. thuringiensis toxinosis.• Speed of kill by the combined pathogens was no greater than that of Bt alone.• Consistent levels of synergism were observed under variable environmental conditions.• Results underscored the strong complementary action of the two biocontrol agents. AbstractStudies were undertaken to further characterize the previously identified synergistic activity of Bacillus thuringiensis-and Beauveria bassiana-based biopesticides against Colorado potato beetle (CPB). A flowable concentrate of B. thuringiensis morrisoni strain tenebrionis (Bt)(Novodor ® FC) and a wettable powder of B. bassiana strain GHA (Bb) (Mycotrol ® 22WP) were applied against CPB larval populations infesting potato in field plots. Novodor FC and an oildispersion formulation of Bb (Mycotrol ES) were applied against second-instar CPB larvae on potted potato plants in greenhouse tests under low relative humidity (RH), variable-temperature conditions. Each pathogen was applied alone and in combination (tank-mixed) with the other pathogen. In the field tests, each biopesticide was also combined with the spray-carrier (formulation without active ingredient) of the other pathogen. Results from the greenhouse tests showed that under warm, dry conditions, low activity of Mycotrol was counterbalanced by high activity of the Novodor, and under cool, somewhat more humid conditions, low Novodor activity was balanced by high activity of Mycotrol, with the result being a constant level of synergism 3 (CPB mortality ca. 20 percentage points higher than predicted by independent action). Similar levels of synergism were observed under the markedly different conditions of the field and greenhouse environments, and the synergism was confirmed as arising from interaction of the two micobes, as the Bt spray carrier had no significant effect on efficacy of the Mycotrol product and the Bb spray carrier had no effect on the efficacy of Novodor. The great capacity of these two control agents to act in concert to control CPB is well documented (the fast-acting, toxic Bt acting to protect potato crops from defoliation and the slow-acting Bb reducing survival to the adult stage). These finding further undersc...

Efficacy of some biorational insecticides against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under laboratory and greenhouse conditions in Kuwait

“…This high efficacy may be due to the additive effects of the biopesticides on the target pest (Srinivasan, ). The high efficacy could also plausibly be due to a synergistic interaction between the biopesticides, by complementarily increasing the sensitivity of the pest (Wraight, & Ramos, ), although this hypothesis has not been tested in the present study. Similar to this study, high efficacy of Azadirachtin when combined with B. thuringiensis against T. absoluta (Abd El‐Ghanny et al, ; Amizadeh et al, ; LO‐Bue, ) or with B. bassiana against T. absolut a (Klieber & Reineke, ; LO‐Bue et al, ) and army worms ( Spodoptera litura ) (Mohan, Reddy, Devi, Kongara, & Sharma, ) has been documented.…”

Endophytic Strain Bacillus subtilis 26DCryChS Producing Cry1Ia Toxin from Bacillus thuringiensis Promotes Multifaceted Potato Defense against Phytophthora infestans (Mont.) de Bary and Pest Leptinotarsa decemlineata Say

“…Thus, the great capacity of Beauveria bassiana strain GHA and B. thuringiensis subsp. morrisoni strain tenebrionis to act in concert to control L. decemlineata was reported (the fast-operating B. thuringiensis δ-endotoxin protects defoliation of potato plants and the slow-operating B. bassiana increases adult mortality) [ 32 ]. The transgenic strain B. bassiana expressing Cyt2Ba had enhanced virulence against larvae and adults of Aedes aegypti and Ae.…”

Integration of Entomopathogenic Fungi into IPM Programs: Studies Involving Weevils (Coleoptera: Curculionoidea) Affecting Horticultural Crops

“…In addition to their direct impact on insect pests, EPF have also been reported to act as endophytes within host plants [ 16 ], can be integrated with attractants for attract-and-kill pest management approaches [ 17 , 18 ], and can be combined with sterile males for integration with the Sterile Insect Technique (SIT) [ 19 , 20 , 21 ]. Entomopathogenic fungi may also have synergistic interactions with some beneficial arthropods (predators, parasitoids, pollinators) [ 22 , 23 , 24 ], other entomopathogens (bacteria and nematodes) [ 25 , 26 ] and synthetic insecticides [ 27 , 28 ] that could be exploited within IPM programs on various crops.…”