Abiotic factors affecting the larvicidal activity of the Bacillus thuringiensis Vip3Aa16 toxin against the lepidopteran pest Ephestia kuehniella

2016 ◽  
Vol 123 (2) ◽  
pp. 59-64 ◽  
Author(s):  
Hanen Boukedi ◽  
Slim Tounsi ◽  
Lobna Abdelkefi-Mesrati
Keyword(s):  
Bacillus Thuringiensis ◽  
Larvicidal Activity ◽  
Abiotic Factors ◽  
Ephestia Kuehniella ◽  
Factors Affecting ◽  
Lepidopteran Pest

scholarly journals Isolation of Bacillus thuringiensis strains from Saudi Arabia soil and study of their potential efficiency against the lepidopteran pest Ephestia kuehniella

2021 ◽  
Vol 12 (2) ◽  
pp. 238-245
Author(s):  
Fidaa Ibrahim Kallaf ◽  
Hanen Boukedi ◽  
Dalel Daâssi ◽  
Lobna Abdelkefi-Mesrati
Keyword(s):  
Saudi Arabia ◽  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Ephestia Kuehniella ◽  
Environment Friendly ◽  
Insecticidal Proteins ◽  
Insect Pathogens ◽  
Bacterium Bacillus ◽  
Parasporal Crystals ◽  
Lepidopteran Pest

Insect pests represent a major threat to food crops and human health, and therefore have to be combated in several ways, including chemical methods. However, researchers demonstrated that these molecules are dangerous for the farmers, consumers and the environment in general. For this reason, scientists permanently searched environment friendly alternatives such as the use of the bacterium Bacillus thuringiensis classified as one of the best insect pathogens. This microorganism is known by its ability to produce two types of insecticidal proteins, Vegetative insecticidal proteins (Vip) and delta-endotoxins produced during vegetative and sporulation stages of growth, respectively. In the present study, 15 B. thuringiensis strains were isolated from soil collected from different regions in Saudi Arabia (Al Baha, Jeddah, Khulis and Yanbu). B. thuringiensis isolates were then classified according to the shape of their parasporal crystals identified under microscope and proteins content of these crystals. Delta-endotoxins efficiency of the different isolates was investigated and promising strains were identified as very active. After 5 days-treatment, B. thuringiensis isolates 14 and 7 killed Ephestia kuehniella larvae with low LC50 of about 59.18 and 65.67 mg/cm2, respectively. The results described in the present study proved that the new B. thuringiensis isolates could be of a great interest in the control of lepidopteran pests by using their delta-endotoxins in bioinsecticide formulations.

A STANDARDIZED BIOASSAY FOR LARVICIDAL ACTIVITY OF BACILLUS THURINGIENSIS IN SUNFLOWER MOTH HOMOEOSOMA ELECTELLUM (LEPIDOPTERA: PHYCITIDAE)

1985 ◽  
Vol 117 (1) ◽  
pp. 15-22 ◽  
Author(s):  
R. G. Lidstone ◽  
D. W. Goerzen ◽  
G. G. Khachatourians
Keyword(s):  
Bacillus Thuringiensis ◽  
Larvicidal Activity ◽  
Standard Test ◽  
Mortality Curve ◽  
Bioassay Technique ◽  
Sunflower Moth ◽  
Homoeosoma Electellum ◽  
Third Instar Larvae

AbstractA standard test for the larvicidal activity of Bacillus thuringiensis (B.t.) against the larvae of the sunflower moth Homoeosoma electellum (Hulst) has been developed. Bioassay parameters investigated include diet preparation, concentration of B.t., effect of formaldehyde, and method of pathogen incorporation in diet. The LC50 for seconded third-instar larvae is 1.24 μg of Dipel® WP ml−1 or 19.8 IU B.t. ml−1 pathogen-incorporated diet. Layering of a pathogen-suspension upon the surface of the diet was not a reliable bioassay technique for H. electellum. The addition of formaldehyde in the diet reduced the slope of the dose–mortality curve but did not change the LC50.

scholarly journals Abiotic factors affecting habitat selection by two invasive gammarids Dikerogammarus villosus and Pontogammarus robustoides

Hydrobiologia ◽  
2017 ◽  
Vol 797 (1) ◽  
pp. 247-263 ◽  
Author(s):  
Jarosław Kobak ◽  
Łukasz Jermacz ◽  
Joanna Marcińczyk ◽  
Ewa Bartoszyńska ◽  
Daria Rutkowska ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Abiotic Factors ◽  
Factors Affecting ◽  
Dikerogammarus Villosus ◽  
Pontogammarus Robustoides

scholarly journals ASSESSMENT OF THE INFLUENCE OF ABIOTIC FACTORS ON THE ENZYMATIVE ACTIVITY OF THE SOIL

ÈKOBIOTEH ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 128-134
Author(s):  
E.V. Tovstik ◽  
◽  
A.S. Olkova ◽  
Keyword(s):  
Enzymatic Activity ◽  
Soil Solution ◽  
Ph Value ◽  
Abiotic Factors ◽  
Inverse Correlation ◽  
Invertase Activity ◽  
Soil Environment ◽  
Factors Affecting ◽  
Activity Of Enzymes ◽  
Made In

Аn attempt is made in this work to establish correlations between the level of enzymatic activity of the soil and factors of an abiotic nature. It was found that the activity of invertase and urease in the soils of more southern territories is higher than that of northern ones. In soils with a pH value of the soil environment close to neutral reaction, the level of enzymatic activity is higher than in more acidic ones. The most sensitive to soil acidity among the studied urease enzymes. In relation to zinc, an inverse correlation was established between its content in the soil and the level of invertase activity. According to the degree of resistance to salinity, the enzymes are arranged in the following order: catalase> invertase> urease. An increase in the mineralization of the soil solution leads to an increase in the activity of urease. Of the studied enzymes, the most labile are representatives of the class of hydrolases (invertase and urease), less labile are oxidoreductases (catalase). Thus, when diagnosing the state of the soil by the level of enzymatic activity, it is necessary to take into account the main abiotic factors affecting the activity of enzymes: the average annual air temperature; pH and mineralization of the soil solution; the content of substances that inhibit microorganisms and block exozymes.

scholarly journals Quantifying the Influence of Larval Density on Disease Transmission Indices in Culex quinquefasciatus, the Major African Vector of Filariasis

2019 ◽  
Vol 11 ◽  
pp. 117954331985602 ◽  
Author(s):  
Azubuike Christian Ukubuiwe ◽  
Chioma Cynthia Ojianwuna ◽  
Israel Kayode Olayemi ◽  
Francis Ofurum Arimoro ◽  
Innocent Chukwuemeka James Omalu ◽  
...  
Keyword(s):  
Culex Quinquefasciatus ◽  
Disease Transmission ◽  
Abiotic Factors ◽  
Larval Density ◽  
Field Trials ◽  
Negative Effects ◽  
Laboratory Findings ◽  
Factors Affecting ◽  
Adult Fitness ◽  
Larval Crowding

Larval crowding is one of the abiotic factors affecting biological fitness in mosquitoes. This study aims at elucidating, quantitatively, the influence of more larval crowding on aspects of fitness in Culex quinquefasciatus mosquito. To this end, day-old larvae of the species were reared in 4 density regimens equivalent to 1 larva in 1.25, 2.5, 5, and 10 mL of distilled water. Developmental indices, adult fitness indices, and accumulation and utilisation of teneral reserves for metamorphosis were determined at these density regimens. The results revealed varying significant negative effects of larval density on all fitness indices measured for the species. The study also revealed high utilisation of teneral reserves for metamorphosis at high larval densities. The information generated will be useful in making informed-decisions in allocating scare resources for vector control, although field trials are advocated to establish these laboratory findings.

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