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

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          Abstract

          BACKGROUND

          The pine weevil ( Hylobius abietis) is a major forest regeneration pest causing high levels of seedling mortality and economic losses. Current management relies on silviculture, stem coatings and insecticides. Here we evaluated for the first time the effects of Bacillus thuringiensis ( Bt) strains on H. abietis adults: two producing the Coleoptera‐targeted toxins Cry3Aa ( Bt tenebrionis NB‐176) and Cry8Da ( Bt galleriae SDS‐502), and one producing the Diptera‐targeted Cry10A ( Bt israelensis AM65‐52). Choice and nonchoice assays using individual and mixtures of Bt formulations, containing these strains respectively, were conducted.

          RESULTS

          We found that Bt had toxic and lethal effects on H. abietis, but effects varied with strain and formulation concentration. The Diptera‐targeted Bt israelensis had the most negative effects on weevil weight, feeding and mortality (70–82% feeding reduction, 65–82% greater mortality than control), whereas the effect was lower for the Coleoptera‐specific Bt tenebrionis (38–42%; 37–42%) and Bt galleriae (11–30%; 15–32%). Reduced weevil feeding was observed after 3 days, and the highest mortality occurred 7–14 days following Bt exposure. However, we found no synergistic toxic effects, and no formulation combination was better than Bt israelensis alone at reducing consumption and survival. Also, pine weevils were not deterred by Bt, feeding equally on Bt‐treated and non‐ Bt treated food.

          CONCLUSION

          There is potential to develop forest pest management measures against H. abietis that include Bt, but only the Diptera‐targeted Bt israelensis would provide effective seedling protection. Its Diptera‐specificity may need reconsideration, and evaluation of other Bt strains/toxins against H. abietis would be of interest. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

          Abstract

          Effects of Bacillus thuringiensis on the pine weevil Hylobius abietis were evaluated for the first time. A Diptera‐targeted strain was most toxic and could enhance forest protection against H. abietis.

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          Most cited references54

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          Fitting Linear Mixed-Effects Models Using lme4

          Maximum likelihood or restricted maximum likelihood (REML) estimates of the parameters in linear mixed-effects models can be determined using the lmer function in the lme4 package for R. As for most model-fitting functions in R, the model is described in an lmer call by a formula, in this case including both fixed- and random-effects terms. The formula and data together determine a numerical representation of the model from which the profiled deviance or the profiled REML criterion can be evaluated as a function of some of the model parameters. The appropriate criterion is optimized, using one of the constrained optimization functions in R, to provide the parameter estimates. We describe the structure of the model, the steps in evaluating the profiled deviance or REML criterion, and the structure of classes or types that represents such a model. Sufficient detail is included to allow specialization of these structures by users who wish to write functions to fit specialized linear mixed models, such as models incorporating pedigrees or smoothing splines, that are not easily expressible in the formula language used by lmer. Journal of Statistical Software, 67 (1) ISSN:1548-7660
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            glmmTMB balances speed and flexibility among packages for zero-inflated generalized linear mixed modeling

            Count data can be analyzed using generalized linear mixed models when observations are correlated in ways that require random effects. However, count data are often zero-inflated, containing more zeros than would be expected from the typical error distributions. We present a new package, glmmTMB, and compare it to other R packages that fit zero-inflated mixed models. The glmmTMB package fits many types of GLMMs and extensions, including models with continuously distributed responses, but here we focus on count responses. glmmTMB is faster than glmmADMB, MCMCglmm, and brms, and more flexible than INLA and mgcv for zero-inflated modeling. One unique feature of glmmTMB (among packages that fit zero-inflated mixed models) is its ability to estimate the Conway-Maxwell-Poisson distribution parameterized by the mean. Overall, its most appealing features for new users may be the combination of speed, flexibility, and its interface’s similarity to lme4. The R journal, 9 (2) ISSN:2073-4859
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              Bacillus thuringiensis Toxins: An Overview of Their Biocidal Activity

              Bacillus thuringiensis (Bt) is a Gram positive, spore-forming bacterium that synthesizes parasporal crystalline inclusions containing Cry and Cyt proteins, some of which are toxic against a wide range of insect orders, nematodes and human-cancer cells. These toxins have been successfully used as bioinsecticides against caterpillars, beetles, and flies, including mosquitoes and blackflies. Bt also synthesizes insecticidal proteins during the vegetative growth phase, which are subsequently secreted into the growth medium. These proteins are commonly known as vegetative insecticidal proteins (Vips) and hold insecticidal activity against lepidopteran, coleopteran and some homopteran pests. A less well characterized secretory protein with no amino acid similarity to Vip proteins has shown insecticidal activity against coleopteran pests and is termed Sip (secreted insecticidal protein). Bin-like and ETX_MTX2-family proteins (Pfam PF03318), which share amino acid similarities with mosquitocidal binary (Bin) and Mtx2 toxins, respectively, from Lysinibacillus sphaericus, are also produced by some Bt strains. In addition, vast numbers of Bt isolates naturally present in the soil and the phylloplane also synthesize crystal proteins whose biological activity is still unknown. In this review, we provide an updated overview of the known active Bt toxins to date and discuss their activities.
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                Author and article information

                Contributors
                adriana.puentes@slu.se
                Journal
                Pest Manag Sci
                Pest Manag Sci
                10.1002/(ISSN)1526-4998
                PS
                Pest Management Science
                John Wiley & Sons, Ltd. (Chichester, UK )
                1526-498X
                1526-4998
                02 November 2020
                March 2021
                : 77
                : 3 ( doiID: 10.1002/ps.v77.3 )
                : 1303-1315
                Affiliations
                [ 1 ] Department of Ecology Swedish University of Agricultural Sciences (SLU) Uppsala Sweden
                [ 2 ] Department of Plant Protection University of Agricultural Sciences and Veterinary Medicine of Cluj‐Napoca (USAMV Cluj Napoca) Cluj‐Napoca Romania
                [ 3 ] SweTree Technologies AB Umeå Sweden
                Author notes
                [*] [* ] Correspondence to: A Puentes, Department of Ecology, Swedish University of Agricultural Sciences (SLU), Box 7044, SE‐75007 Uppsala, Sweden. E‐mail: adriana.puentes@ 123456slu.se

                Author information
                https://orcid.org/0000-0001-9393-7449
                Article
                PS6144
                10.1002/ps.6144
                7894551
                33078548
                d782bef4-f813-4479-90a6-09c31bb2a1fb
                © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

                This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

                History
                : 22 July 2020
                : 05 October 2020
                : 19 October 2020
                Page count
                Figures: 6, Tables: 6, Pages: 13, Words: 10524
                Funding
                Funded by: Stora Enso Oyj , open-funder-registry 10.13039/501100009236;
                Categories
                Research Article
                Research Articles
                Custom metadata
                2.0
                March 2021
                Converter:WILEY_ML3GV2_TO_JATSPMC version:5.9.7 mode:remove_FC converted:19.02.2021

                Pests, Diseases & Weeds
                biopesticides,forest pest,forest regeneration,insecticidal toxins,pest management,plant protection

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