A reliable bioassay procedure to evaluate Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae)
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| Format: | Artículo científico |
| Sprache: | en |
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Universidad de Costa Rica
2007
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| _version_ | 1876428114429476864 |
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| author | Jorge E. Ibarra |
| author_facet | Jorge E. Ibarra |
| contents | A reliable bioassay procedure to evaluate Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae) Jorge E. Ibarra Rebeca Mora Ana M. Espinoza Biología δ rearing bioassay Homoptera sugar diet A reliable bioassay procedure was developed to test ingested Bacillus thuringiensis (Bt) toxins on therice delphacid Tagosodes orizicolus. Initially, several colonies were established under greenhouse conditions,using rice plants to nurture the insect. For the bioassay, an in vitro feeding system was developed for third tofourth instar nymphs. Insects were fed through Parafilm membranes on sugar (10 % sucrose) and honey bee(1:48 vol/vol) solutions, observing a natural mortality of 10-15 % and 0-5 %, respectively. Results were reproducibleunder controlled conditions during the assay (18±0.1 °C at night and 28±0.1 °C during the day, 80 %RH and a 12:12 day:light photoperiod). In addition, natural mortality was quantified on insect colonies, collectedfrom three different geographic areas of Costa Rica, with no significant differences between colonies under controlledconditions. Finally, bioassays were performed to evaluate the toxicity of a Bt collection on T. orizicolus. Apreliminary sample of twenty-seven Bt strains was evaluated on coarse bioassays using three loops of sporulatedcolonies in 9 ml of liquid diet, the strains that exhibited higher percentages of T. orizicolus mortality were furtheranalyzed in bioassays using lyophilized spores and crystals (1 mg/ml). As a result, strains 26-O-to, 40-X-m, 43-S-d and 23-O-to isolated from homopteran insects showed mortalities of 74, 96, 44 and 82 % respectively whileHD-137, HD-1 and Bti showed 19, 83 and 95 % mortalities. Controls showed mortalities between 0 and 10 % inall bioassays. This is the first report of a reliable bioassay procedure to evaluate per os toxicity for a homopteranspecies using Bacillus thuringiensis strains. Rev. Biol. Trop. 55 (2): 373-383. Epub 2007 June, 29. 2007 artículo científico 0034-7744 https://www.redalyc.org/articulo.oa?id=44955203 en http://www.redalyc.org/revista.oa?id=449 Revista de Biología Tropical application/pdf Universidad de Costa Rica Revista de Biología Tropical (Costa Rica) Num.2 Vol.55 |
| format | Artículo científico |
| id | redalyc_44955203 |
| institution | Redalyc |
| language | en |
| publishDate | 2007 |
| publisher | Universidad de Costa Rica |
| spellingShingle | A reliable bioassay procedure to evaluate Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae) Jorge E. Ibarra Biología δ rearing bioassay Homoptera sugar diet A reliable bioassay procedure to evaluate Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae) Jorge E. Ibarra Rebeca Mora Ana M. Espinoza Biología δ rearing bioassay Homoptera sugar diet A reliable bioassay procedure was developed to test ingested Bacillus thuringiensis (Bt) toxins on therice delphacid Tagosodes orizicolus. Initially, several colonies were established under greenhouse conditions,using rice plants to nurture the insect. For the bioassay, an in vitro feeding system was developed for third tofourth instar nymphs. Insects were fed through Parafilm membranes on sugar (10 % sucrose) and honey bee(1:48 vol/vol) solutions, observing a natural mortality of 10-15 % and 0-5 %, respectively. Results were reproducibleunder controlled conditions during the assay (18±0.1 °C at night and 28±0.1 °C during the day, 80 %RH and a 12:12 day:light photoperiod). In addition, natural mortality was quantified on insect colonies, collectedfrom three different geographic areas of Costa Rica, with no significant differences between colonies under controlledconditions. Finally, bioassays were performed to evaluate the toxicity of a Bt collection on T. orizicolus. Apreliminary sample of twenty-seven Bt strains was evaluated on coarse bioassays using three loops of sporulatedcolonies in 9 ml of liquid diet, the strains that exhibited higher percentages of T. orizicolus mortality were furtheranalyzed in bioassays using lyophilized spores and crystals (1 mg/ml). As a result, strains 26-O-to, 40-X-m, 43-S-d and 23-O-to isolated from homopteran insects showed mortalities of 74, 96, 44 and 82 % respectively whileHD-137, HD-1 and Bti showed 19, 83 and 95 % mortalities. Controls showed mortalities between 0 and 10 % inall bioassays. This is the first report of a reliable bioassay procedure to evaluate per os toxicity for a homopteranspecies using Bacillus thuringiensis strains. Rev. Biol. Trop. 55 (2): 373-383. Epub 2007 June, 29. 2007 artículo científico 0034-7744 https://www.redalyc.org/articulo.oa?id=44955203 en http://www.redalyc.org/revista.oa?id=449 Revista de Biología Tropical application/pdf Universidad de Costa Rica Revista de Biología Tropical (Costa Rica) Num.2 Vol.55 |
| title | A reliable bioassay procedure to evaluate Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae) |
| topic | Biología δ rearing bioassay Homoptera sugar diet |
| url | https://www.redalyc.org/articulo.oa?id=44955203 |