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Development of entomopathogenic fungal library with insecticidal activity against whitefly
Sehyeon Baek,Sihyeon Kim,Jong Cheol Kim,Mi Rong Lee,So Eun Park,Dongwei Li,Tae Young Shin,Jae Su Kim 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.10
Whitefly has a broad host range of more than 600 species, and 40 biotypes have been reported worldwide. Among the various ecological types, B and Q are the most problematic. Especially, Biotype Q, which causes serious damage in the green house, mediates more than 40 kinds of viruses, including Tomato yellow leaf cull virus (TYLCV). The development of resistance to whitefly, adverse effects on non-target organisms, and strengthened legal regulations are making chemical control difficult in application. For these reasons, the use of alternative strategies is needed to suppress the Biotype Q whitefly population. Entomopathogenic fungi were investigated and developed to control hard-control insect pest, such as whitefly. These fungi are natural pathogen of their invertebrate host and contribute to the regulation of their host population in the environment. In addition, these agents are typically harmless to humans and non-targeted organisms and do not adversely impact the environment. Therefore, in this study, we screened pathogenic fungi against whitefly using our entomopathogenic fungal library, and virulence tests were conducted with conoidal suspension (1×107conidia/ml) in laboratory conditions. As a result, 10 isolates showed 80-100% mortality at 5 days after treatment. We will analyze the characteristics of these fungal isolates and evaluate their potential as insecticides against whitefly. The selected isolates against the high mortality of whiteflies can be effectively used in integrated pest management programs for whiteflies.
Insecticidal activity of entomopathogenic fungal species against silverleaf whitefly, Bemisia tabaci
Sehyeon Baek,Sihyeon Kim,Jong Cheol Kim,Mi Rong Lee,So Eun Park,Dongwei Li,Laila Gasmi,Tae Young Shin,Jae Su Kim 한국응용곤충학회 2019 한국응용곤충학회 학술대회논문집 Vol.2019 No.04
Silverleaf whitefly, Bemisia tabaci is a worldwide agricultural pest that cause serious damage to crops. However, since this insect developed resistance to variety of chemicals, alternative control strategy needs to be studied. In this study, we aimed to evaluate the potential of entomopathogenic fungi as biological control tools against this pest. We developed a dipping method in laboratory conditions to screen insecticidal activity of different fungal species and isolates against the nymphal stage of whitefly. The highly virulent isolates were characterized and 2 isolates were further selected based on their high conidial productivity and thermotolerance. Finally, several grain substrates were used to confirm the conidial productivity and thermotolerance of the selected isolates, revealing optimum conidial production when the fungi were cultured on millet grains. Both isolates could be used in further millet grain-based formulations to control the whitefly in fields.
Laila Gasmi,Sehyeon Baek,Jong Cheol Kim,Mi Rong Lee,Jae Su Kim 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.10
Beauveria comprises entomopathogenic fungi frequently isolated from insect cadavers, among which Beauveria bassiana is the most widely studied species of entomopathogenic fungal genus for its high potential as a biological pesticide. Even though it has been reported that B. bassiana is a heterogeneous assemblage of strains, little is known about the factors that might drive the genetic diversity among various isolates. In this work, we ought to study the gene diversity of 33 isolates in order to figure out the relationship between their gene diversity and biological features. First, we analyzed gene sequences that are involved in developmental and immunological processes of the fungal isolates and host. Now we are checking whether the gene diversity is related to the genes function, the isolates geographic localization, thermo-tolerance and virulence of the isolates. The obtained results so far showed no correlation between the genetic diversity and the fungal geographic localization. But interestingly, a positive correlation has been obtained between the virulence and the genetic diversity based on the internal transcribed spacers (ITS). Further analyses are aiming to confirm the obtained data and to analyze possible correlations between the genetic diversity and morphological and transcriptional data of the studied isolates. Based on the obtained results, we could much strongly focus on interesting genes which might be related to improving or screening highly virulent fungal agents as biological control agents.
Gene diversity shapes biological features of entomopathogenic Beauveria bassiana
Laila Gasmi,Sehyeon Baek,Jong Cheol Kim,Mi Rong Lee,Sihyeon Kim,So Eun Park,Dongwei Li,Tae Young Shin,Jae Su Kim 한국응용곤충학회 2019 한국응용곤충학회 학술대회논문집 Vol.2019 No.04
Beauveria bassiana is widely studied for its potential as biopesticide. However, little is known about the factors to influence genetic diversity among isolates. In this work, we aimed to study the gene diversity of 42 isolates to figure out the impact of sequences variability on various biological features. The accumulated data showed no correlation between sequence variability and the fungal geographic localization. Meanwhile, weak to strong correlations have been obtained between the sequence diversity of various genes and the studied biological features. Interestingly, Biotrophy-associated gene 2 gene variability was correlated with all the studied biological features, being an important marker to determine isolates of interest for biological control. Therefore, the obtained data would serve as a database to focus on interesting genes related to improving or screening highly virulent isolates as biological control agents.
김종철,Se Jin Lee,김시현,이미롱,Sehyeon Baek,박소은,김준헌,Tae Young Shin,Jae Su Kim 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.1
Chemical control is widely used to control the Japanese pine sawyer beetle, Monochamus alternatus, but strong chemical regulations require an environmentally sound management strategy. In this work, we investigated the use of entomopathogenic fungi and their application as a means of practical pest management. Thirty-two diverse species of fungal isolates were assayed against adult pine sawyer beetles using a contact method under laboratory conditions, and four isolates showed over 70% virulence consequently. These isolates, two each of Beauveria bassiana and Metarhizium anisopliae were sprayed on the adult beetles at 1 × 10 7 conidia/ml in plastic containers, respectively. The M. anisopliae-treated adult beetles showed 67% mortality. M. anisopliae isolates JEF-197 and JEF-279 demonstrated dosage-dependent insecticidal activity. Following the laboratory experiments, semi-field trials were conducted in young pine trees under high (RH 94%) and low (RH 35%) humidity conditions. In the high humidity conditions, most of the adult beetles stayed on the top of the branches. When the two M. anisopliae isolates were sprayed on the beetles, they showed ca. 50–70% insecticidal activity 11 days after application. In contrast, in low humidity conditions, the adult beetles tried to move off the branches and onto the soil. When the beetles reached the JEF-197 and JEF-279-treated soil, we measured > 90% insecticidal activity. This work suggests that M. anisopliae was the most virulent entomopathogenic fungus against adult Japanese pine sawyer beetles, and this forest insect could be ecologically controlled by the spray and soil application of the M. anisopliae isolates.