Cruciferous crops comprise one of the major crop divisions and contribute significantly to global crop production. Insect pests associated with cruciferous crops have the potential to destroy harvests. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) and cabbage aphids, Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae) are considered the most important cabbage pests in South Africa. Pest control in cabbage is still heavily reliant on use of insecticides even though insecticide application usually result in increased pest status of P. xylostella. Use of integrated pest management (IPM) strategies may yet prove invaluable as a means of suppressing the more serious cabbage pests. Global interest in cultural control strategies, that includes intercropping of unrelated crop plants, has been rekindled because of problems experienced with pesticide use. A study that involved the planting of two field trials with cabbage and carrot plants in different ratios, as a substitutive intercropping system, was undertaken during the 2002/03 and 2003/04 planting seasons. Field trials had five treatments viz. control (cabbage monoculture sprayed with mercaptothion), cabbage monoculture (without chemical application), 1:1 intercropping (cabbage:carrots), 1:3 intercropping and 1:5 intercropping, replicated six times in a randomized block design. Insects were sampled weekly by removing the third-youngest open leaf, from one plant per plot (six plants per treatment). Feeding damage to cabbage leaves was assessed visually by rating 14 plants per plot according to a numeric scale based on damage severity. P. xylostella and aphid parasitism levels were determined. Prominence values were calculated for P. xylostella larvae and aphids for each treatment per sampling date. P. xylostella infestations and parasitism levels were significantly (P ≤ 0.05) lower in control treatments. Intercropping ratio did not have a significant impact on pest infestations. P. xylostella infestations and parasitism on intercropping treatments did not differ significantly (P > 0.05) from that on monoculture plots (except for 1:5 intercropping during the 2003/04 season). Cotesia plutellae (Hymenoptera: Braconidae) was the dominant parasitoid and parasitism levels were significantly correlated with P. xylostella infestation levels. Prominence values showed a decline in P. xylostella infestations on intercropping treatments towards the last sampling date during both seasons. Feeding damage severity was lowest on the control treatment but similar for other treatments for both seasons. Aphid infestations were significantly (P ≤ 0.05) lower on the control treatment, but did not differ significantly between intercropping treatments. Aphid prominence values indicated possible suppression of infestations at low population levels during the early part of the season. Aphid parasitism was low during both seasons. It seems more likely that the reduction in insect infestation levels reported from the literature are related more to spatial arrangement of plants than cropping ratios. The observed suppression of aphid infestation levels on intercropped plots early in the season may be valuable in reducing the need for early chemical applications. The limiting of early insecticide application against aphids may result in a reduced pest status of P. xylostella, due to the conservation of C. plutellae populations. / Thesis (M. Environmental Science))--North-West University, Potchefstroom Campus, 2007.

Cruciferous crops comprise one of the major crop divisions and contribute significantly to global crop production. Insect pests associated with cruciferous crops have the potential to destroy harvests. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) and cabbage aphids, Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae) are considered the most important cabbage pests in South Africa. Pest control in cabbage is still heavily reliant on use of insecticides even though insecticide application usually result in increased pest status of P. xylostella. Use of integrated pest management (IPM) strategies may yet prove invaluable as a means of suppressing the more serious cabbage pests. Global interest in cultural control strategies, that includes intercropping of unrelated crop plants, has been rekindled because of problems experienced with pesticide use. A study that involved the planting of two field trials with cabbage and carrot plants in different ratios, as a substitutive intercropping system, was undertaken during the 2002/03 and 2003/04 planting seasons. Field trials had five treatments viz. control (cabbage monoculture sprayed with mercaptothion), cabbage monoculture (without chemical application), 1:1 intercropping (cabbage:carrots), 1:3 intercropping and 1:5 intercropping, replicated six times in a randomized block design. Insects were sampled weekly by removing the third-youngest open leaf, from one plant per plot (six plants per treatment). Feeding damage to cabbage leaves was assessed visually by rating 14 plants per plot according to a numeric scale based on damage severity. P. xylostella and aphid parasitism levels were determined. Prominence values were calculated for P. xylostella larvae and aphids for each treatment per sampling date. P. xylostella infestations and parasitism levels were significantly (P ≤ 0.05) lower in control treatments. Intercropping ratio did not have a significant impact on pest infestations. P. xylostella infestations and parasitism on intercropping treatments did not differ significantly (P > 0.05) from that on monoculture plots (except for 1:5 intercropping during the 2003/04 season). Cotesia plutellae (Hymenoptera: Braconidae) was the dominant parasitoid and parasitism levels were significantly correlated with P. xylostella infestation levels. Prominence values showed a decline in P. xylostella infestations on intercropping treatments towards the last sampling date during both seasons. Feeding damage severity was lowest on the control treatment but similar for other treatments for both seasons. Aphid infestations were significantly (P ≤ 0.05) lower on the control treatment, but did not differ significantly between intercropping treatments. Aphid prominence values indicated possible suppression of infestations at low population levels during the early part of the season. Aphid parasitism was low during both seasons. It seems more likely that the reduction in insect infestation levels reported from the literature are related more to spatial arrangement of plants than cropping ratios. The observed suppression of aphid infestation levels on intercropped plots early in the season may be valuable in reducing the need for early chemical applications. The limiting of early insecticide application against aphids may result in a reduced pest status of P. xylostella, due to the conservation of C. plutellae populations. / Thesis (M. Environmental Science))--North-West University, Potchefstroom Campus, 2007.

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 115-117). Also available via the Internet.

Thesis (M. Sc. (Zoology & Entomology))--Rhodes University, 2004.

Thesis--Cornell University, 1962. / Includes bibliographical references (leaves 75-94).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-03Bitstream added on 2014-06-13T19:37:24Z : No. of bitstreams: 1 schlicksouza_ec_me_botfca.pdf: 597062 bytes, checksum: 5c66dcaf6b112711ef4eb09b3fdc515a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A couve-de-folha, Brassica oleracea (L.) var. acephala, é atacada por diversas pragas, e o curuquerê, Ascia monuste orseis (Godart) (Lepidoptera: Pieridae), destaca-se como uma das mais importantes, causando intensas desfolhas às plantas. O principal método de controle deste inseto é feito através da aplicação de inseticidas sintéticos, com reconhecidos prejuízos ao meio ambiente. Considerando-se a importância desse inseto para a cultura da couve-de-folha e também os efeitos indesejáveis decorrentes de aplicações de inseticidas para seu controle, a presente pesquisa teve como objetivo avaliar a resistência de genótipos de couve-de-folha frente A. monuste orseis e estudar os tipos de resistência envolvidos através da realização de ensaios com adultos (atratividade e preferência para oviposição) e lagartas (preferência alimentar e antibiose), sob condições de laboratório e casade- vegetação. Para a instalação dos bioensaios, foi mantida uma criação de A. monuste orseis em casa-de-vegetação. Foram avaliados 29 genótipos de couve-de-folha: Manteiga de Ribeirão Pires I-2620 (MRP I-2620), Manteiga I-1811 (M I-1811), Roxa I-919 (R I-919), Manteiga de São Roque I-1812 (MSR I-1812), Gigante I-915 (G I-915), Manteiga I-916 (M I- 916), Crespa I-918 (C I-918), Manteiga de Ribeirão Pires I-2446 (MRP I-2446), Crespa de Capão Bonito (CCB), Manteiga de Tupi (MT), Couve de Leguminosas (CL), Manteiga de Jundiaí (MJ), Manteiga de Mococa (MM), Manteiga São José (MSJ), Verde-escura (VE), Pires 1 de Campinas (P1C), Pires 2 de Campinas (P2C), Japonesa (J), Hortolândia (H), Orelha de Elefante (OE), Vale das Garças (VG), Comum (C), Introduções do município de Arthur Nogueira: variedades Y (IMAN Y); W (IMAN W); Z (IMAN Z) e comerciais: Cabocla (CS);Couve de folhas Manteiga 900 Legítima Pé Alto (CFMLPA), Couve de folhas Manteiga Tronchuda Portuguesa (CFMTP) Couve Manteiga... / Cabagge (Brassica oleracea L. var. acephala), is attacked by several pests, being the caterpillar Ascia monuste orseis (Godart) (Lepidoptera: Pieridae), pointed as one of the most important, causing severe defoliation on plants. The main method of controlling this insect was done by the application of synthetic insecticides with recognized damage to the environment. Considering the importance of the insect for the cabagge culture and the undesirable effects arising of the insecticides application for their control, the present research had as objective to evaluate the resistance of cabagge genotypes against A. monuste orseis, and verify the types of resistance involved through the accomplishment of assays with adults (attractiveness and oviposition preference) and caterpillars (feeding preference and antibiosis), in laboratory and greenhouse conditions. A rearing of A. monuste orseis was maintained in the greenhouse in order to instal the bioassays. 29 genotypes of cabagge were evaluated: Manteiga de Ribeirão Pires I-2620 (MRP I-2620), Manteiga I-1811 (M I-1811), Roxa I-919 (R I-919), Manteiga de São Roque I-1812 (MSR I-1812), Gigante I-915 (G I-915), Manteiga I-916 (M I-916), Crespa I-918 (C I-918), Manteiga de Ribeirão Pires I-2446 (MRP I-2446), Crespa de Capão Bonito (CCB), Manteiga de Tupi (MT), Couve de Leguminosas (CL), Manteiga de Jundiaí (MJ), Manteiga de Mococa (MM), Manteiga São José (MSJ), Verde-escura (VE), Pires 1 de Campinas (P1C), Pires 2 de Campinas (P2C), Japonesa (J), Hortolândia (H), Orelha de Elefante (OE), Vale das Garças (VG), Comum (C), Introduções do município de Arthur Nogueira: variedades... (Complete abstract click electronic access below)

The efficiency of the carabid beetle, Bembidion lampros (Herbst) as a predator of the eggs of Hylemya brassicae (Bouché) and the effects of the insecticides Dipel, methomyl and chlorfenvinphos on the beetle were studied by introducing some B. lampros into experimental plots of Brussels sprouts and restricting their movements by surrounding the plots with polythene barriers. More eggs were laid in the first than in the second generation of the cabbage root fly. There was progressive decrease in the number of root fly eggs and the number of B. lampros as the plants matured. During the first generation the untreated control had significantly more eggs than the other treatments. Egg predation by B. lampros resulted in a 45% reduction. In plots containing B. lampros and treated with methomyl, Dipel or chlorfenvinphos, the numbers of eggs were reduced by 35, 44 and 66% respectively. Laboratory toxicity studies showed that methomyl at 1 g/ litre produced 100% mortality of B. lampros one day after treatment. When the rate was reduced to 1/2, 1/4 and 1/8, the mortality of B. lampros dropped to 70, 40 and 20% respectively. Dipel [Bacillus thurinqiensis Berliner (16000 IU/mg)] at 1 g/litre and 5 g/litre and chlorfenvinphos at 10 ppm and 40 ppm; produced no mortality three days after treatment. Foliar application of methomyl for aphid control in the field significantly reduced the B. lampros population. There was no significant effect on B. lampros when Dipel was applied as a foliar spray to control lepidopterous larvae. Chlorfenvinphos granules applied once early in the season as a subsurface treatment prevented damage by cabbage maggot and was not toxic to B. lampros. Cabbage maggot damage was not severe enough to cause significant reduction in yield at harvest but examination of roots showed that untreated plots had significantly more maggot damage than other treatments. The damage index ranged from 2.5 for untreated plants to 0.0 in plants from plots treated with chlorfenvinphos and containing B. lampros. Although differences were not significant, the numbers of overwintering root fly puparia were highest in untreated plots. Significantly more empty puparia, indicating second generation fly emergence, were also found in the untreated plots. Besides B. lampros, other carabids removed from the experimental plots included: Harpalus affinis Schr., Amara spp., Calathus fuscipes Goeze, Pterostichus melanarius 111. and other Bembidion spp., in decreasing order of abundance. B. lampros alone does not give complete protection against root maggot, especially if fly oviposition is very heavy during the first generation when the beetle is most effective. But the beetle will go a long way to suppress part of the population. The use of non-selective insecticides for control of pests of Brassica may lead to reduction of B. lampros populations and a consequent increase in cabbage maggot attack. / Land and Food Systems, Faculty of / Graduate

No description available.