Food Consumption and Survival of Trichoplusia ni (Lepidoptera: Noctuidae) Larvae Following Intoxication by Bacillus thuringiensis var. kurstaki and Thuringiensin

1991 ◽  
Vol 84 (2) ◽  
pp. 436-439 ◽  
Author(s):  
A. H. Gharib ◽  
J. A. Wyman
Keyword(s):  
Bacillus Thuringiensis ◽  
Food Consumption ◽  
Trichoplusia Ni ◽  
Lepidoptera Noctuidae

Positive association between resistance to Bacillus thuringiensis and overwintering survival of cabbage loopers, Trichoplusia ni (Lepidoptera: Noctuidae)

2008 ◽  
Vol 98 (3) ◽  
pp. 317-322 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Positive Association ◽  
Pest Species ◽  
Development Of Resistance ◽  
Trade Offs ◽  
Major Pest ◽  
Selection For ◽  
Overwintering Survival ◽  
Lepidoptera Noctuidae

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

scholarly journals SELEÇÃO E CARACTERIZAÇÃO MOLECULAR DE BACILLUS THURINGIENSIS BERLINER COM ATIVIDADE TÓXICA PARA TRICHOPLUSIA NI HUEBNER (LEPIDOPTERA: NOCTUIDAE)

2010 ◽  
Vol 77 (4) ◽  
pp. 685-692
Author(s):  
E.D. Grecco ◽  
R.A. Polanczyk ◽  
D. Pratissoli
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Lepidoptera Noctuidae

RESUMO Trichoplusia ni é uma praga polífaga importante em plantios de crucíferas, soja e algodão. O presente estudo objetivou selecionar e caracterizar por método molecular isolados de Bacillus thuringiensis (Bt) com potencial para atuar com agentes de controle biológico de T. ni. Para os bioensaios de patogenicidade, uma alíquota com 3 x 108 esporos/mL de suspensão de Bt de cada isolado foi aplicada na superfície do disco de dieta artificial, previamente distribuída em placas de acrílico com 50 lagartas, distribuídas em 5 repetições. Nos bioensaios para a obtenção da CL50, apenas os isolados com 100% de mortalidade foram pré-selecionados, sendo testadas as seguintes concentrações: 102, 5 x 102, 103, 2 x 103, 4 x 103, 6 x 103, 8 x 103 esporos/mL, sendo os tratamentos compostos por 120 lagartas, distribuídas em 3 repetições. Foi feita caracterização molecular para detectar os genes cry1, cry2 e Vip para os isolados que obtiveram mortalidade acima de 95%. Os isolados HD-1 (Padrão), Bt-1043N-V, Bt-1034F, Bt-1009K, Bt-1000, Bt-969A causaram 100% de mortalidade nos testes de patogenicidade e CL50 de 1,17 x 103, 1,45 x 103, 1,46 x 103, 1,01 x 103, 9,43 x 102, 1,22 x 103, respectivamente. Não foram encontrados genes cry1, cry2 e Vip nos isolados testados, podendo outras toxinas Cry estar causando a mortalidade de T. ni, visto que os isolados testados são específicos para a ordem Lepidoptera. Estes isolados mostraram potencial para o controle de T. ni, sendo virulentos a este inseto, com potencial para serem utilizados em programa de manejo desta praga.

Tobacco Budworm, Heliothis virescens (Lepidoptera: Noctuidae): Larval Location and Mortality on Bacillus thuringiensis-Treated Cotton

1999 ◽  
Vol 34 (4) ◽  
pp. 426-434 ◽  
Author(s):  
J. L. Jyoti ◽  
S. Y. Young ◽  
D. T. Johnson ◽  
R. W. McNew
Keyword(s):  
Bacillus Thuringiensis ◽  
Leaf Area ◽  
Food Consumption ◽  
Heliothis Virescens ◽  
Untreated Control ◽  
Larval Mortality ◽  
Tobacco Budworm ◽  
Lepidoptera Noctuidae ◽  
Larval Movement

One-d-old Heliothis virescens (F.) larvae were placed on Bacillus thuringiensis var. kurstaki Berliner-treated cotton leaves and terminals in the laboratory. Larval movement, food consumption and mortality were examined at 3, 6, 12, 24 and 48 h. Untreated leaves had a greater percentage of larvae on their under side than on their upper side; this location was not influenced by treatment with B. thuringiensis. When B. thuringiensis was applied to cotton terminals, first instars moved from B. thuringiensis-treated meristems; this movement increased with an increase in rate. Bacillus thuringiensis treatment also resulted in increased movement of larvae from the leaves and terminals onto the inner cup surface, although this movement was significantly greater than the untreated control only during the first 12 h after treatment. The leaf area consumed decreased with an increase in B. thuringiensis rate, but was not significantly correlated with larval mortality.

scholarly journals Bacillus thuringiensis Bel Protein Enhances the Toxicity of Cry1Ac Protein to Helicoverpa armigera Larvae by Degrading Insect Intestinal Mucin

2009 ◽  
Vol 75 (16) ◽  
pp. 5237-5243 ◽  
Author(s):  
Shangling Fang ◽  
Li Wang ◽  
Wei Guo ◽  
Xia Zhang ◽  
Donghai Peng ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Trichoplusia Ni ◽  
Knockout Mutant ◽  
Gene Encoding ◽  
In Vitro Degradation ◽  
Intestinal Mucin ◽  
Helicoverpa Armígera ◽  
Cry1ac Protein

ABSTRACT Bacillus thuringiensis has been used as a bioinsecticide to control agricultural insects. Bacillus cereus group genomes were found to have a Bacillus enhancin-like (bel) gene, encoding a peptide with 20 to 30% identity to viral enhancin protein, which can enhance viral infection by degradation of the peritrophic matrix (PM) of the insect midgut. In this study, the bel gene was found to have an activity similar to that of the viral enhancin gene. A bel knockout mutant was constructed by using a plasmid-free B. thuringiensis derivative, BMB171. The 50% lethal concentrations of this mutant plus the cry1Ac insecticidal protein gene were about 5.8-fold higher than those of the BMB171 strain. When purified Bel was mixed with the Cry1Ac protein and fed to Helicoverpa armigera larvae, 3 μg/ml Cry1Ac alone induced 34.2% mortality. Meanwhile, the mortality rate rose to 74.4% when the same amount of Cry1Ac was mixed with 0.8 μg/ml of Bel. Microscopic observation showed a significant disruption detected on the midgut PM of H. armigera larvae after they were fed Bel. In vitro degradation assays showed that Bel digested the intestinal mucin (IIM) of Trichoplusia ni and H. armigera larvae to various degrading products, similar to findings for viral enhancin. These results imply Bel toxicity enhancement depends on the destruction of midgut PM and IIM, similar to the case with viral enhancin. This discovery showed that Bel has the potential to enhance insecticidal activity of B. thuringiensis-based biopesticides and transgenic crops.

Effects of host plant,Gossypium hirsutum L., on sexual attraction of cabbage looper moths,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae)

1994 ◽  
Vol 20 (11) ◽  
pp. 2959-2974 ◽  
Author(s):  
P. J. Landolt ◽  
R. R. Heath ◽  
J. G. Millar ◽  
K. M. Davis-Hernandez ◽  
B. D. Dueben ◽  
...  
Keyword(s):  
Gossypium Hirsutum ◽  
Host Plant ◽  
Trichoplusia Ni ◽  
Sexual Attraction ◽  
Cabbage Looper ◽  
Gossypium Hirsutum L ◽  
Lepidoptera Noctuidae
Sign in / Sign up

Export Citation Format

Share Document