{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/39942"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/39942","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Impact of the microbial pesticide Bacillus thruingiensis Berliner subsp. kurstaki on Hymenopterous parasites of the imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae)","abstract":"Three formulations of Bacillus thuringiensis Berliner subsp. kurstaki (Dipel 4L, Dipel 2X, and ABG-6167) were compared with the synthetic pyrethroid perrnethrin ( common name Pounce 3. 2 EC) for insecticidal activity and impact upon parasitism of the imported cabbageworrn, Pieris rapae (L.) (Lepidoptera: Pieridae) in field broccoli (CV Packrnan) from fall 1986 to spring 1988. Perrnethrin, Dipel 4L, and ABG-6167 were not significantly different in their efficacy towards imported cabbageworm larvae. Parasitization of P. rapae by the larval parasite Cotesia glomerata (L.) (Hymenoptera: Braconidae) and the pupal parasite Pteromalus puparum (L.) (Hyrnenoptera: Pteromalidae) continued after spraying in the B. thuringiensis plots, but was not significantly different from perrnethrin. However, 100% of the P. rapae chrysalids recovered were parasitized by P. puparum. The impact of seasonal hyperparasitism was compared between .Q. glomerata, and a Yugoslavian strain of Cotesia rubecula (Marshall), an exotic larval parasite of the imported cabbageworm. Four hyperparasites, two of them attacking both~. glomerata and~. rubecula, were found in field plots from 1986-1988. The level of hyperparasitization for the two primary parasites was significantly different. Hyperparasitization averaged only 8.1% for C. glomerata from 1986-1988, but was 37. 9% for C. rubecula from 1987-1988. During the early- to mid-season of 1988, hyperparasite activity was not detectable and C. rubecula outcompeted C. glomerata for hosts; but by mid-season, hyperparasite activity against C. rubecula increased to 100%, causing its populations to crash. C. glomerata then became the dominant parasite of P. rapae. C. rubecula was not recovered in 1989. Hyperparasites may be a limiting factor in establishing C. rubecula in southwestern Virginia. Mortality and successful pupation of P rapae fourth instars parasitized by C. rubecula to B. thuringiensis endotoxin at dosages of 850, 85, and 8.5 I.U./ml was examined. After day two, the LC<sub>50</sub>'s of parasitized fourth instars were approximately thirty times higher than that of unparasitized larvae and by day four, the LC<sub>50</sub> response of parasitized fourth instars was 180 times higher than unparasitized larvae. Twenty-five percent of parasitized fourth instars exposed to a concentration of 850 I.U./ml successfully pupated, compared to 76% at 85 I.U./ml and 69% at 8.5 I.U./ml. Parasitized fourth instar P. rapae consume less food and are therefore less susceptible to B. thuringiensis than unparasitized larvae at the same dosages.","abstract_html":"Three formulations of Bacillus thuringiensis Berliner subsp. kurstaki (Dipel 4L, Dipel 2X, and ABG-6167) were compared with the synthetic pyrethroid perrnethrin ( common name Pounce 3. 2 EC) for insecticidal activity and impact upon parasitism of the imported cabbageworrn, Pieris rapae (L.) (Lepidoptera: Pieridae) in field broccoli (CV Packrnan) from fall 1986 to spring 1988. Perrnethrin, Dipel 4L, and ABG-6167 were not significantly different in their efficacy towards imported cabbageworm larvae. Parasitization of P. rapae by the larval parasite Cotesia glomerata (L.) (Hymenoptera: Braconidae) and the pupal parasite Pteromalus puparum (L.) (Hyrnenoptera: Pteromalidae) continued after spraying in the B. thuringiensis plots, but was not significantly different from perrnethrin. However, 100% of the P. rapae chrysalids recovered were parasitized by P. puparum. The impact of seasonal hyperparasitism was compared between .Q. glomerata, and a Yugoslavian strain of Cotesia rubecula (Marshall), an exotic larval parasite of the imported cabbageworm. Four hyperparasites, two of them attacking both~. glomerata and~. rubecula, were found in field plots from 1986-1988. The level of hyperparasitization for the two primary parasites was significantly different. Hyperparasitization averaged only 8.1% for C. glomerata from 1986-1988, but was 37. 9% for C. rubecula from 1987-1988. During the early- to mid-season of 1988, hyperparasite activity was not detectable and C. rubecula outcompeted C. glomerata for hosts; but by mid-season, hyperparasite activity against C. rubecula increased to 100%, causing its populations to crash. C. glomerata then became the dominant parasite of P. rapae. C. rubecula was not recovered in 1989. Hyperparasites may be a limiting factor in establishing C. rubecula in southwestern Virginia. Mortality and successful pupation of P rapae fourth instars parasitized by C. rubecula to B. thuringiensis endotoxin at dosages of 850, 85, and 8.5 I.U./ml was examined. After day two, the LC&lt;sub&gt;50&lt;/sub&gt;&#x27;s of parasitized fourth instars were approximately thirty times higher than that of unparasitized larvae and by day four, the LC&lt;sub&gt;50&lt;/sub&gt; response of parasitized fourth instars was 180 times higher than unparasitized larvae. Twenty-five percent of parasitized fourth instars exposed to a concentration of 850 I.U./ml successfully pupated, compared to 76% at 85 I.U./ml and 69% at 8.5 I.U./ml. Parasitized fourth instar P. rapae consume less food and are therefore less susceptible to B. thuringiensis than unparasitized larvae at the same dosages.","abstract_has_math":false,"creators":["McDonald, Richard C."],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Entomology","degree_department":"Entomology","school":null,"contributors":[],"advisors":[],"committee_chairs":["Kok, Loke T."],"committee_members":["Eaton, Judith L.","O’Dell, Charles R.","Pienkowski, Robert L.","Ravlin, F. William","Yousten, Al A."],"year":1990,"date_issued":"1990","date_published":"1990","updated_at":"2026-07-22T22:19:33Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-10192005-113246"],"render_values":[{"text":"etd-10192005-113246","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/39942","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Kok, Loke T."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Eaton, Judith L.","O’Dell, Charles R.","Pienkowski, Robert L.","Ravlin, F. 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(Lepidoptera: Pieridae) in field broccoli (CV Packrnan) from fall 1986 to spring 1988. Perrnethrin, Dipel 4L, and ABG-6167 were not significantly different in their efficacy towards imported cabbageworm larvae. Parasitization of P. rapae by the larval parasite Cotesia glomerata (L.) (Hymenoptera: Braconidae) and the pupal parasite Pteromalus puparum (L.) (Hyrnenoptera: Pteromalidae) continued after spraying in the B. thuringiensis plots, but was not significantly different from perrnethrin. However, 100% of the P. rapae chrysalids recovered were parasitized by P. puparum. The impact of seasonal hyperparasitism was compared between .Q. glomerata, and a Yugoslavian strain of Cotesia rubecula (Marshall), an exotic larval parasite of the imported cabbageworm. Four hyperparasites, two of them attacking both~. glomerata and~. rubecula, were found in field plots from 1986-1988. The level of hyperparasitization for the two primary parasites was significantly different. Hyperparasitization averaged only 8.1% for C. glomerata from 1986-1988, but was 37. 9% for C. rubecula from 1987-1988. During the early- to mid-season of 1988, hyperparasite activity was not detectable and C. rubecula outcompeted C. glomerata for hosts; but by mid-season, hyperparasite activity against C. rubecula increased to 100%, causing its populations to crash. C. glomerata then became the dominant parasite of P. rapae. C. rubecula was not recovered in 1989. Hyperparasites may be a limiting factor in establishing C. rubecula in southwestern Virginia. Mortality and successful pupation of P rapae fourth instars parasitized by C. rubecula to B. thuringiensis endotoxin at dosages of 850, 85, and 8.5 I.U./ml was examined. After day two, the LC<sub>50</sub>'s of parasitized fourth instars were approximately thirty times higher than that of unparasitized larvae and by day four, the LC<sub>50</sub> response of parasitized fourth instars was 180 times higher than unparasitized larvae. Twenty-five percent of parasitized fourth instars exposed to a concentration of 850 I.U./ml successfully pupated, compared to 76% at 85 I.U./ml and 69% at 8.5 I.U./ml. Parasitized fourth instar P. rapae consume less food and are therefore less susceptible to B. thuringiensis than unparasitized larvae at the same dosages."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Impact of the microbial pesticide Bacillus thruingiensis Berliner subsp. kurstaki on Hymenopterous parasites of the imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae)"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Kok, Loke T."],"dc:contributor.committeemember":["Eaton, Judith L.","O’Dell, Charles R.","Pienkowski, Robert L.","Ravlin, F. William","Yousten, Al A."],"dc:contributor.department":["Entomology"],"dc:creator":["McDonald, Richard C."],"dc:date.accessioned":["2014-03-14T21:21:27Z"],"dc:date.available":["2014-03-14T21:21:27Z","2005-10-19"],"dc:date.issued":["1990"],"dc:description.abstract":["Three formulations of Bacillus thuringiensis Berliner subsp. kurstaki (Dipel 4L, Dipel 2X, and ABG-6167) were compared with the synthetic pyrethroid perrnethrin ( common name Pounce 3. 2 EC) for insecticidal activity and impact upon parasitism of the imported cabbageworrn, Pieris rapae (L.) (Lepidoptera: Pieridae) in field broccoli (CV Packrnan) from fall 1986 to spring 1988. Perrnethrin, Dipel 4L, and ABG-6167 were not significantly different in their efficacy towards imported cabbageworm larvae. Parasitization of P. rapae by the larval parasite Cotesia glomerata (L.) (Hymenoptera: Braconidae) and the pupal parasite Pteromalus puparum (L.) (Hyrnenoptera: Pteromalidae) continued after spraying in the B. thuringiensis plots, but was not significantly different from perrnethrin. However, 100% of the P. rapae chrysalids recovered were parasitized by P. puparum. The impact of seasonal hyperparasitism was compared between .Q. glomerata, and a Yugoslavian strain of Cotesia rubecula (Marshall), an exotic larval parasite of the imported cabbageworm. Four hyperparasites, two of them attacking both~. glomerata and~. rubecula, were found in field plots from 1986-1988. The level of hyperparasitization for the two primary parasites was significantly different. Hyperparasitization averaged only 8.1% for C. glomerata from 1986-1988, but was 37. 9% for C. rubecula from 1987-1988. During the early- to mid-season of 1988, hyperparasite activity was not detectable and C. rubecula outcompeted C. glomerata for hosts; but by mid-season, hyperparasite activity against C. rubecula increased to 100%, causing its populations to crash. C. glomerata then became the dominant parasite of P. rapae. C. rubecula was not recovered in 1989. Hyperparasites may be a limiting factor in establishing C. rubecula in southwestern Virginia. Mortality and successful pupation of P rapae fourth instars parasitized by C. rubecula to B. thuringiensis endotoxin at dosages of 850, 85, and 8.5 I.U./ml was examined. After day two, the LC<sub>50</sub>'s of parasitized fourth instars were approximately thirty times higher than that of unparasitized larvae and by day four, the LC<sub>50</sub> response of parasitized fourth instars was 180 times higher than unparasitized larvae. Twenty-five percent of parasitized fourth instars exposed to a concentration of 850 I.U./ml successfully pupated, compared to 76% at 85 I.U./ml and 69% at 8.5 I.U./ml. Parasitized fourth instar P. rapae consume less food and are therefore less susceptible to B. thuringiensis than unparasitized larvae at the same dosages."],"dc:description.degree":["Ph. D."],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-10192005-113246"],"dc:identifier.uri":["http://hdl.handle.net/10919/39942"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Impact of the microbial pesticide Bacillus thruingiensis Berliner subsp. kurstaki on Hymenopterous parasites of the imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae)"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Entomology"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:33Z"}