Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm
Forest protection against eastern spruce budworm, <i>Choristoneura fumiferana</i> (Clemens), relies on aerial applications of <i>Bacillus thuringiensis</i> (<i>Btk</i>). However, <i>Btk</i> prescriptions have been developed for balsam fir (<i>Abi...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-06-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/14/7/1289 |
| _version_ | 1797589337927319552 |
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| author | Alvaro Fuentealba Émile Pelletier-Beaulieu Alain Dupont Christian Hébert Richard Berthiaume Éric Bauce |
| author_facet | Alvaro Fuentealba Émile Pelletier-Beaulieu Alain Dupont Christian Hébert Richard Berthiaume Éric Bauce |
| author_sort | Alvaro Fuentealba |
| collection | DOAJ |
| description | Forest protection against eastern spruce budworm, <i>Choristoneura fumiferana</i> (Clemens), relies on aerial applications of <i>Bacillus thuringiensis</i> (<i>Btk</i>). However, <i>Btk</i> prescriptions have been developed for balsam fir (<i>Abies balsamea</i> (L.) Mill.) stands, generating uncertainty as to the relevance of this protection approach on white spruce (<i>Picea glauca</i> (Moench) Voss). The main goal of this study was to evaluate the efficacy of three <i>Btk</i> application treatments (early application, late application, and double application) for protecting white spruce and balsam fir in mixed stands. Our results show that all <i>Btk</i> treatments tested kept defoliation under the 50% threshold on balsam fir (27.7 to 38.1% less defoliation than in controls). In contrast, differences in defoliation among treatments were not significant for white spruce. Larval mortality was significantly lower on white spruce than on balsam fir. The low efficacy of <i>Btk</i> treatments on white spruce may be explained by its shoot phenology (most bud caps were still present during the early application), and its foliar chemistry, which could decrease <i>Btk</i> efficacy. Consequently, many larvae may survive simply because <i>Btk</i> spores do not reach them, or because they may consume sublethal doses. We recommend maintaining the current strategy in mixed stands, as it provides a good protection for balsam fir. Further research is needed to determine the causes of the low efficacy of <i>Btk</i> treatments on white spruce. |
| first_indexed | 2024-03-11T01:05:04Z |
| format | Article |
| id | doaj.art-e88ef48bdf7c4bb89498ebaa9d0334a6 |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-11T01:05:04Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Forests |
| spelling | doaj.art-e88ef48bdf7c4bb89498ebaa9d0334a62023-11-18T19:22:05ZengMDPI AGForests1999-49072023-06-01147128910.3390/f14071289Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce BudwormAlvaro Fuentealba0Émile Pelletier-Beaulieu1Alain Dupont2Christian Hébert3Richard Berthiaume4Éric Bauce5Département des Sciences du Bois et de la Forêt, Faculté de Foresterie, de Géographie et de Géomatique, Université Laval, Quebec City, QC G1V 0A6, CanadaDépartement des Sciences du Bois et de la Forêt, Faculté de Foresterie, de Géographie et de Géomatique, Université Laval, Quebec City, QC G1V 0A6, CanadaSociété de Protection des Forêts Contre les Insectes et Maladies (SOPFIM), Quebec City, QC G1N 4B8, CanadaNatural Resources Canada, Canadian Forest Service, 1055 du P.E.P.S., Sainte-Foy, QC G1V 4C7, CanadaSociété de Protection des Forêts Contre les Insectes et Maladies (SOPFIM), Quebec City, QC G1N 4B8, CanadaDépartement des Sciences du Bois et de la Forêt, Faculté de Foresterie, de Géographie et de Géomatique, Université Laval, Quebec City, QC G1V 0A6, CanadaForest protection against eastern spruce budworm, <i>Choristoneura fumiferana</i> (Clemens), relies on aerial applications of <i>Bacillus thuringiensis</i> (<i>Btk</i>). However, <i>Btk</i> prescriptions have been developed for balsam fir (<i>Abies balsamea</i> (L.) Mill.) stands, generating uncertainty as to the relevance of this protection approach on white spruce (<i>Picea glauca</i> (Moench) Voss). The main goal of this study was to evaluate the efficacy of three <i>Btk</i> application treatments (early application, late application, and double application) for protecting white spruce and balsam fir in mixed stands. Our results show that all <i>Btk</i> treatments tested kept defoliation under the 50% threshold on balsam fir (27.7 to 38.1% less defoliation than in controls). In contrast, differences in defoliation among treatments were not significant for white spruce. Larval mortality was significantly lower on white spruce than on balsam fir. The low efficacy of <i>Btk</i> treatments on white spruce may be explained by its shoot phenology (most bud caps were still present during the early application), and its foliar chemistry, which could decrease <i>Btk</i> efficacy. Consequently, many larvae may survive simply because <i>Btk</i> spores do not reach them, or because they may consume sublethal doses. We recommend maintaining the current strategy in mixed stands, as it provides a good protection for balsam fir. Further research is needed to determine the causes of the low efficacy of <i>Btk</i> treatments on white spruce.https://www.mdpi.com/1999-4907/14/7/1289spruce budwormforest protectionspray operations<i>Bacillus thuringiensis</i>balsam firwhite spruce |
| spellingShingle | Alvaro Fuentealba Émile Pelletier-Beaulieu Alain Dupont Christian Hébert Richard Berthiaume Éric Bauce Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm Forests spruce budworm forest protection spray operations <i>Bacillus thuringiensis</i> balsam fir white spruce |
| title | Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm |
| title_full | Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm |
| title_fullStr | Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm |
| title_full_unstemmed | Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm |
| title_short | Optimizing <i>Bacillus thuringiensis</i> (<i>Btk</i>) Aerial Spray Prescriptions in Mixed Balsam Fir-White Spruce Stands against the Eastern Spruce Budworm |
| title_sort | optimizing i bacillus thuringiensis i i btk i aerial spray prescriptions in mixed balsam fir white spruce stands against the eastern spruce budworm |
| topic | spruce budworm forest protection spray operations <i>Bacillus thuringiensis</i> balsam fir white spruce |
| url | https://www.mdpi.com/1999-4907/14/7/1289 |
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