scholarly journals Chickpea-mediated effects of Bacillus thuringiensis on Helicoverpa armigera and its larval parasitoid, Campoletis chlorideae

2010 ◽  
Vol 134 (9-10) ◽  
pp. 682-693 ◽  
Author(s):  
M. K. Dhillon ◽  
H. C. Sharma
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Campoletis Chlorideae ◽  
Mediated Effects ◽  
Larval Parasitoid ◽  
Helicoverpa Armígera

Impact of Abiotic Factors and Dates of Sowing on Helicoverpa armigera (Hübner) Parasitoid Campoletis chloridae (Uchida) under Chickpea Cropping System in Tarai Region of Uttarakhand

2021 ◽  
Author(s):  
S.D. Divija ◽  
Meena Agnihotri
Keyword(s):  
Helicoverpa Armigera ◽  
Abiotic Factors ◽  
Cropping System ◽  
Weather Factors ◽  
Campoletis Chlorideae ◽  
Minimum Relative Humidity ◽  
Larval Parasitoid ◽  
Helicoverpa Armígera ◽  
The Impact ◽  
Helicoverpa Armigera Hubner

Background: The solitary endo-larval parasitoid Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important biocontrol agent of H. armigera in chickpea ecosystem. Abiotic factors are likely to affect the insect host and activity of its parasitoid. Therefore, the present study was conducted to understand the impact of weather factors and different dates of sowing on per cent parasitization of Helicoverpa armigera (Hübner) by Campoletis chlorideae (Uchida) in chickpea ecosystem.Methods: In this field-laboratory investigation were carried out at Pantnagar during the cropping season of 2017-18. Twenty-five larvae of H. armigera (first and second instars) were collected randomly at weekly basis from untreated chickpea crop. In the laboratory, the collected larvae were reared till parasitoid emergence and observed for per cent parasitisation. Result: The observation recorded revealed that mean seasonal parasitism by Campoletis on larvae of H. armigera was found to be 21%, 43.5% and 34.5% in early (20th October), normal (11th November) and late sown crop (1st December), respectively. Various abiotic parameters like maximum and minimum temperature, maximum and minimum relative humidity registered high level of significant association with per cent parasitization in early and normal sown crop compared to the low level of association in late sown crop. The multiple regression analysis showed that the combined effect of all the meteorological parameters were responsible for 90%, 57.9% and 30.5% variation in per cent parasitization in early, normal and late sown crop, respectively.

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.

Incidence of Helicoverpa armigera (Lepidoptera: Noctuidae) and its natural enemies on smallholder crops in Kenya

1993 ◽  
Vol 83 (3) ◽  
pp. 321-328 ◽  
Author(s):  
H. van den Berg ◽  
M. J. W. Cock ◽  
G. I. Oduor ◽  
E. K. Onsongo
Keyword(s):  
Helicoverpa Armigera ◽  
Heliothis Armigera ◽  
Population Densities ◽  
Parasitoid Species ◽  
Larval Parasitoid ◽  
Total Percentage ◽  
Four Seasons ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae ◽  
Experimental Plots

AbstractSmallholder crops (sunflower, maize, sorghum and cotton) were grown in experimental plots at seven sites, representing different agricultural zones of Kenya, over four seasons. Helicoverpa armigera (Hübner) (formerly Heliothis armigera) only occasionally achieved population densities sufficient to cause obvious damage to the crops, and was virtually absent from the coastal sites. At the inland sites, infestation and mortality levels varied greatly. Information is presented on the incidence of H. armigera, and the identity, distribution and frequency of its common parasitoids and (potential) predators, sampled in the experimental plots. Trichogrammatoidea spp., egg parasitoids, and Linnaemya longirostris (Macquart), a tachinid late-larval parasitoid, were the most common parasitoid species, but total percentage parasitism was rather low. Of the large complex of predators, only anthocorids and ants (predominantly Pheidole spp., Myrmicaria spp. and Camponotus spp.) were sufficiently common and widespread to be of importance in suppressing H. armigera. The abundance of predators fluctuated widely between sites, but anthocorids were most abundant at the western sites.

Sign in / Sign up

Export Citation Format

Share Document