Scientific-technological analysis and biological aspects of entomopathogenic fungus Aschersonia

Entomopathogenic fungus belonging to the genus Aschersonia [Sordariomycetes: Hypocreales: Clavicipitaceae] is known for its high virulence against Aleyrodidae and Coccoidea. Its first use as a biological control agent date back to 1921 in Florida, when it was reported to be active against citrus whiteflies. Despite its recognized effectiveness, after a century no formulations based on Aschersonia are available for use as a biopesticide. The main aim of this study was to analyze the available patents and scientific articles involving this genus to understand the current scenario with respect to the scientific and technological development. To accomplish this objective, scientific and patent databases were surveyed, firstly using the terms ‘Entomopathogenic fungi, ‘Aschersonia’, ‘Beauveria’ and ‘Metarhizium’ to understand the overall scenario of scientific and technological production for entomopathogenic fungi. This was followed by a more detailed analysis for the genus Aschersonia. Our study demonstrates that there is little advancement with respect to research and technological development with this fungus. A total of 83 articles and 110 patents were found with the term “Aschersonia” in titles or abstracts. After the exclusion of articles and patents in duplicates, and without Aschersonia as the focus, 18 articles and 21 patents remained. Most of the scientific and technological production obtained described the production of enzymes and mycotoxins, focusing on other biotechnological applications rather than its use as an insecticidal agent. We elucidate possible difficulties for the use of this fungus as a biological control agent and provide a future perspective on its use in biotechnological products.     

Formulation and characterization of the microencapsulated entomopathogenic fungus Metarhizium anisopliae MA126

Abstract

Bioinsecticides are expected to be used for controlling major species of aphids. The present study explored a liquid phase coating technique for the formulation of microencapsulated conidia of the entomopathogenic fungus Metarhizium anisopliae MA126. Various parameters for microencapsulation were investigated. The biopolymers sodium alginate, hydroxypropyl methyl cellulose (HPMC) and chitosan were tested as coating materials. Calcium chloride was used as the cross-linking agent for converting soluble sodium alginate into an insoluble form. To improve the efficiency of microencapsulation, the additives of HPMC, dextrin, chitosan or HPMC/chitosan in various ratios (1 : 1, 1 : 3 and 3 : 1) were used as the coating materials. The particle size of a bare microcapsule was less than 30 µm. Larger size microcapsules were produced using vortex method by comparison with that using homogenization method. The latter method, however, was easy to scale up. The effect of coating materials on the morphology and encapsulation efficiency of the microcapsules was also studied. The best encapsulation efficiency (78%) was using HPMC as the additive of the coating material. The next was dextrin (70%). By measuring the germination rate, the results showed that the activity was ～80% of the initial after 6 months of storage at 4°C, while that of the bare conidia was less than 50% stored in identical conditions.     

Histopathological,cytotoxicological, and genotoxic effects of the semi-synthetic compound dillapiole n-butyl ether in Balb/C mice

ABSTRACT

Dillapiole n-butyl ether is a substance derived from dillapiole, which exhibits potential insecticidal effects on Aedes aegypti, the principal vector of the Dengue fever, Zika, and Chikungunya viruses, as well as Aedes albopictus, a vector of Dengue fever. As these mosquitoes are resistant to synthetic insecticides, dillapiole n-butyl ether may represent a valuable, plant-based alternative for their control. Dillapiole n-butyl ether has insecticidal and genotoxic effects on A. aegypti and A. albopictus, as shown by the reduction in clutch size and egg viability, and increased mortality rates, as well as a high frequency of micronuclei and chromosomal aberrations. However, the potential cytotoxic and genotoxic effects of this substance in mammals are still unknown. In Balb/C mice, structural changes were detected in hepatic, renal, and cardiac tissues, which were directly proportional to the concentration of the dose applied, in both genders. The induction of genotoxic, mutagenic, and cytotoxic effects was also observed at the highest concentrations (150 and 328 mg/kg). Further research will be necessary to better characterize the potential genotoxicity of this substance at lower concentrations, for the evaluation of the potential health risks related to its presence in environmental features, such as drinking water.     

Bioactivity of seagrass against the dengue fever mosquito Aedes aegypti larvae

Objective

To identify the larvicidal activity of the seagrass extracts.

Methods

Seagrass extracts, Syringodium isoetifolium (S. isoetifolium), Cymodocea serrulata and Halophila beccarii, were dissolved in DMSO to prepare a graded series of concentration. Batches of 25 early 4th instars larvae of Aedes aegypti (Ae. aegypti) were transferred to 250 mL enamel bowl containing 199 mL of distilled water and 1 mL of plant extracts (0.01 mg – 0.1 mg). After 24 h the mortality rate was identified with the formulae [(% of test mortality – % of control mortality)/(100 – % of control mortality)] × 100. Each experiment was conducted with three replicates and a concurrent control group. A control group consisted of 1 mL of DMSO and 199 mL of distilled water only.

Results

: The root extract of S. isoetifolium showed maximum larvicidal activity with minimum concentration of extract of LC₅₀= 0.0 604 ± 0.0 040)µg/mL with lower confidence limit (LCL) – upper confidence limit (UCL) = (0.051–0.071) and LC₉₀=0.0 972µg/mL followed by leaf extract of S. isoetifolium showed LC₅₀= (0.062 ± 0.005)µg/mL. The regression equation of root and leaf extract of S. isoetifolium for 4th instar larvae were Y= 4.909 + 1.32x (R²= 0.909) and Y= 2.066 + 1.21x (R² =0.897) respectively. The results of the preliminary phytochemical constituents shows the presence of saponin, steroids, terpenoid, phenols, protein and sugars.

Conclusions

From the present study the ethanolic extracts of seagrass of S. isoetifolium possesses lead compound for development of larvicidal activity.