Insect killing fungus Beauveria bassiana has been widely studied as a biological control agent. However, many studies have been focused on lab or field-based management. Herein this work, comparison of three B. bassiana strains was investigated under a molecular level. The whole genome sequences of ERL836, JEF-007 were analyzed by PacBio (35.5 Mb of ERL836 and 36.5 Mb of JEF-007) and ARSEF2860 referenced from GenBank (33.7 Mb). To compare the three strains, virulence, thermotolerance and chemical resistance were assayed. The transcriptomes of non-infecting B. bassiana and infecting B. bassiana against western flower thrips were analyzed using RNA-seq. This work can provide that genome features, functions, morphology and gene expression could be different under the molecular level, even if in the same species.

Trialeurodes vaporariorum is an important greenhouse pest worldwide. We compared the efficacy of a new strain of Beauveria bassiana (ARP14) with a commercialized one (GHA) against 2nd instar and 4th instar of T. vaporarioum. Those nymphs were exposed to the fungus in a concentration of 1×108 conidia/mL by leaf dipping method. There was no difference in mycosis rates at any observation time between the two strains in both 2nd (100.0%) and 4th instar (100.0%). Lethal median time (LT50) wasn't different between the two strains in both 2nd and 4th instar. In conclusion, the new B. bassiana strain (ARP14) would be a good candidate of mycoinsecticide for whitefly management.

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is a major pest of apple, peach, and plum in Korea. As a series of experiment we assessed effect of combined application of an entomopathogenic fungi (Beauveria bassiana ARP-14) and a botanical insecticide (azadirachtin) against male and female of adult G. molesta (<5 days old) in glass scintillation vials. LT50 value of combined application of ARP-14 and azadirachtin (51.9 h) was larger than that of positive control λ-cyhalothrin (34.4 h) in adult female G. molesta. But, adult male G. molesta didn't show any statistical difference between the combined application (34.2 h) and λ-cyhalothrin (44.1). Thus, combined application of ARP-14 and azadirachtin can be an optional management tactic against G. molesta.

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.

A species of Beauveria bassiana is widely used for biological pest management in many countries. Many efforts have been given to figure out the clear fungal mode of action to enhance the insecticidal activity. Homologous recombination (knock-out) or hairpin RNA (knock-down) is popularly used in fungal gene function study, but gene cloning and generation of knock-out or -down mutants takes long time or temporarily knock-downed. Here in this work, we used previously generated egfp-expressing B. bassiana strain (Bb-egfp #3) and integrated dsegfp to the Bb-egfp #3 using a protoplast integration method. This work suggests that protoplast integration with dsRNA possibly generate significantly reduced gene expression in B. bassiana and the reduction is quite stable over generations which provide easy of functional study for fungal mode of action.

Insect-killing fungi have high potential in pest management. A deeper insight into the fungal genes at the whole genome level is necessary to understand the inter-species or intra-species genetic diversity of fungal genes, and to select excellent isolates. In this work, we conducted a whole genome sequencing of Beauveria bassiana (Bb) JEF-007 and characterized pathogenesis-related features and compared with other isolates including Bb ARSEF2860. A large number of Bb JEF-007 genes showed high identity with Bb ARSEF2860, but some genes showed moderate or low identity. The two Bb isolates showed a significant difference in vegetative growth, antibiotic-susceptibility, and virulence against Tenebrio molitor larvae. When highly identical genes between the two Bb isolates were subjected to real-time PCR, their transcription levels were different, particularly in heat shock protein 30 (hsp30) gene which is related to conidial thermotolerance. In several B. bassiana isolates, chitinases and trypsin-like protease genes involved in pathogenesis were highly conserved, but other genes showed noticeable sequence variation within the same species. Given the transcriptional and genetic diversity in B. bassiana, a selection of virulent isolates with industrial advantages is a pre-requisite, and this genetic approach could support the development of excellent biopesticides with intellectual property protection.

Bemisia tabaci (Gennadius) is an important polyphagous pest and transmits plant pathogenic virus to numerous agriculture crops. We compared the efficacy of Beauveria bassiana ARP14 strain with commercialized GHA strain against 2nd instar and 4th instar of B. tabaci. The nymphs were exposed in 1×108 conidia/mL by dipping method. There was no difference in mycosis rate between the two strains in both 2nd and 4th instar. After 72 h, mycosis rate of 2nd instar was 100.0% in B. bassiana ARP14 strain followed by 97.4% in B. bassiana GHA strain. In 4th instar, B. bassiana ARP14 strain caused 100.0% while B. bassiana GHA strain caused 93.3%.

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.

To find best humidity condition for the use of Beauveria ARP14 against Grapholita molesta (Busck), first instar of G. molesta was treated with three conidial concentrations (1×107, 1×108, and 1×109 conidia/ml) in three different relative humidities (RH; 55, 75, and 95%). Mortality varied depending on concentration and humidity. Mortality in 95% RH was 1.5 and 2.7 times higher than 75 and 52% humidity at 1×109 conidia/ml and 16 hours after the exposure. However, the mycosis rates after 14 days were all not different among the treatments. In conclusion B. bassiana ARP14 could be most effective when applied higher at RH condition.

Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is an important pest of pome and stone fruits, i.e., apple, peach, and plum. We evaluated single or combined application of an entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin. ARP14 (1×108 conidia/mL) and a botanical insecticide of azadirachtin (Azatrol, PBI/Gordon Cooperation) (10 mL/L) against first instar larvae (<5 h old) of G. molesta in glass scintillation vial bioassay. Combined use of B. bassiana ARP-14 and azadirachtin showed higher corrected morality of 100% at 8 h than 71.4% in λ-cyhalothrin used as a positive control.

Beauveria bassiana (Bb) is a potential biopesticide against western flower thrips. To understand molecular characteristics of two Bb isolates (ERL836 and JEF-007), whole genome sequencing and RNA-seq were performed. The whole genome of Bb ERL836 was sequenced (3,934,801,443 bp) using Pacbio sequencing and 15 contigs were analyzed. To understand the molecular mechanisms of pathogenicity in two Bb genome (before infection and after infection), next generation sequencing (NGS) was analyzed to compare transcriptomes. A result of differentially expressed gene (DEG) showed that 2,689 contigs were up-regulated and 2,619 contigs were down-regulated. Randomly selected five genes were validated to be highly up-regulated. This work can provide an understanding of the interaction between Bb and westetn flower thrips.

The hawthorn spider mite, Amphitetranychus viennensis (Zacher), is an important tetranychid causing damage on fruittrees and woody ornamental plants. We investigated the effect of a mycoinsecticide BotaniGard® ES at different humiditylevels on the eggs and adults mortality of A. viennensis. In a laboratory condition, egg mortality was significantly influencedby the conidial concentration and RHs. Highest mortality of eggs was observed at 1×108 conidia/ml with 95% RH thanother conditions. In 1×108 conidia/ml, LT50 at 95 and 75% RH were significantly different from 55% RH. In BotaniGard®spray in cherry plants, mites decreased on day 6 at all the concentrations, but the mite populations rebounded exceptin 1×109 conidia/ml where it maintained 0 until 9 days after spraying. It is therefore concluded that B. bassiana hasa potential to be used against A. viennensis

총채벌레 2종(꽃노랑총채벌레, 대만총채벌레)에 대한 Beauverai bassiana ERL 836 상업화 제품 원제의 약효를반수치사포자수(LS50-1 cm2)를 기준으로 평가하였다. 전반적으로 처리 2일차부터 약효가 나타났으며 번데기와 성충의LS50 값의 범위로 평가 시 번데기에 대한 효과가 성충보다 높은 것으로 관찰되었다. 특히, 4종의 살충제(Acrinathrin,Chlorfenapyr, Spinosad, Thiamethoxam)에 복합저항성을 나타내는 꽃노랑총채벌레 2개 지역 계통에 대해서도 약효를나타내어, 향후 B. bassiana ERL 836 상업화 제품을 활용한 저항성 총채벌레 관리의 정밀 연구가 필요할 것으로판단된다.