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Abstract Chalcones are intermediate products in the biosynthesis of flavonoids, which possess a wide range of biological properties, including antimicrobial and anticancer activities. The introduction of a chlorine atom and the glucosyl moiety into their structure may increase their bioavailability, bioactivity, and pharmacological use. The combined chemical and biotechnological methods can be applied to obtain such compounds. Therefore, 2-chloro-2′-hydroxychalcone and 3-chloro-2′-hydroxychalcone were synthesized and biotransformed in cultures of two strains of filamentous fungi, i.e. Isaria fumosorosea KCH J2 and Beauveria bassiana KCH J1.5 to obtain their novel glycosylated derivatives. Pharmacokinetics, drug-likeness, and biological activity of them were predicted using cheminformatics tools. 2-Chloro-2′-hydroxychalcone, 3-chloro-2′-hydroxychalcone, their main glycosylation products, and 2′-hydrochychalcone were screened for antimicrobial activity against several microbial strains. The growth of Escherichia coli 10,536 was completely inhibited by chalcones with a chlorine atom and 3-chlorodihydrochalcone 2′-O-β-d-(4″-O-methyl)-glucopyranoside. The strain Pseudomonas aeruginosa DSM 939 was the most resistant to the action of the tested compounds. However, chalcone aglycones and glycosides with a chlorine atom almost completely inhibited the growth of bacteria Staphylococcus aureus DSM 799 and yeast Candida albicans DSM 1386. The tested compounds had different effects on lactic acid bacteria depending on the tested species. In general, chlorinated chalcones were more effective in the inhibition of the tested microbial strains than their unchlorinated counterparts and aglycones were a little more effective than their glycosides.

Chalcones, secondary plant metabolites, exhibit various biological properties. The introduction of a chlorine and a glucosyl substituent to the chalcone could enhance its bioactivity and bioavailability. Such compounds can be obtained through a combination of chemical and biotechnological methods. Therefore, 4-chloro-2′-hydroxychalcone and 5′-chloro-2′-hydroxychalcone were obtained by synthesis and then glycosylated in two filamentous fungi strains cultures, i.e., Isaria fumosorosea KCH J2 and Beauveria bassiana KCH J1.5. The main site of the glycosylation of both compounds by I. fumosorosea KCH J2 was C-2′ and C-3 when the second strain was utilized. The pharmacokinetics of these compounds were predicted using chemoinformatics tools. Furthermore, antimicrobial activity tests were performed. Compounds significantly inhibited the growth of the bacteria strains Escherichia coli 10536, Staphylococcus aureus DSM 799, and yeast Candida albicans DSM 1386. Nevertheless, the bacterial strain Pseudomonas aeruginosa DSM 939 exhibited significant resistance to their effects. The growth of lactic acid bacteria strain Lactococcus acidophilus KBiMZ 01 bacteria was moderately inhibited, but strains Lactococcus rhamnosus GG and Streptococcus thermophilus KBM-1 were completely inhibited. In summary, chalcones substituted with a chlorine demonstrated greater efficacy in inhibiting the microbial strains under examination compared to 2′-hydroxychalcone, while aglycones and their glycosides exhibited similar effectiveness. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Sweet potato whitefly (Bemisia tabaci) is one of the most destructive pests to an extensive range of crops and vegetables. Pesticide‐dependent management programs have led to severe health problems, including pesticide poisoning and cancer in human beings, as well as pesticide resistance in insect pests. Entomopathogenic fungi (EPF) are considered safe and highly effective against many pests. Therefore, identifying the pathogenicity and virulence of EPFs against Bemisia tabaci is a valuable addition to the management of their infestations. In this study, we investigated the efficacy of conidia suspensions of Aschersonia aleyrodis, Isaria fumosorosea, Beauveria bassiana, and Akanthomyces muscarius (= Lecanicillium muscarium) against nymphal stages of Bemisia tabaci in cucumber seedlings under both optimal and suboptimal conditions. RESULTS: All of the EPFs demonstrated significant ovicidal effects, with the highest cumulative mortalities observed in Aschersonia aleyrodis (96.46%) and I. fumosorosea‐treated (94.60%) seedlings against host eggs and crawlers. Similarly, in the L4‐instars experiment, Aschersonia aleyrodis and I. fumosorosea were the most efficient, resulting in cumulative mortalities of 94.82% and 94.75%, respectively. However, Bemisia tabaci cumulative mortalities on seedlings treated with Akanthomyces muscarius (78.36%) and Beauveria bassiana (85.90%) were also significantly different from untreated seedlings (7.10%). Under suboptimal relative humidity (RH) conditions (≤ 45% RH), Aschersonia aleyrodis exhibited greater tolerance to harsh conditions, causing a significantly higher infection rate in L1–L2 nymphs (~92%) compared to the approximately 32% infected young nymphs observed in I. fumosorosea‐treated seedlings. CONCLUSION: All the selected EPF were more effective against the young nymphal instars. Our results also highlight the efficacy of Aschersonia aleyrodis under suboptimal conditions. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Biological control nowadays is rapidly growing to reduce the incessant use of chemical insecticides for control of various insect pests. In the present study, entomopathogenic fungi are used to determine insecticidal activity against walnut blue butterfly under laboratory conditions. The experimental setup was completely randomized design (CRD) with two treatments along with control with different concentrations of entomopathogenic fungi. The bioassay was carried out by spraying second larval instar of Chaetoprocta odata [Hewitson 1865] with 1, 2, 3 & 4 % conidial concentration of Beauveria bassiana (Balsamo) Vuill. (1912) and Isaria fumosorosea Wize (1904). The results of this study showed that all the concentrations showed remarkable pathogenic activity but I. fumosorosea was highly pathogenic and recorded the highest mortality rate of 93.33 % after 144 hours compared to B. bassiana where 73.33 % mortality was reported. LC50 values for B. bassiana (4.15) was higher than that of I. fumosorosea (3.34) which indicates that I. fumosorosea was more effective against C. odata population. Among different concentrations of I. fumosorosea, 4 % concentration was the most effective with lowest LC50 values.

The European grapevine moth (Lobesia botrana) is currently the most damaging pest in many viticultural regions of South and Central Europe and is highly responsible for the development of secondary infections by Botrytis cinerea to both table and wine grapes. Entomopathogenic fungi (EPF) are considered as substantial biological control agents of insect pests. However, they are able to infect their hosts only under a narrow spectrum of environmental conditions. In this study, the effects of temperature on pathogenicity of EPF for the control of L. botrana are reported. Among a collection of 33 EPF isolates, six virulent isolates were selected for the experiments. The bioassays took place at controlled conditions, under the temperature regimes of 20, 22.5, 25, 27.5, 30, and 32.5 °C. A conidial concentration of 1 × 108 conidia/ml was prepared for each isolate, and fungi were applied by spraying them on third-instar larvae (L3) of L. botrana. Both factors, fungal isolate and temperature, significantly affected mortality of L. botrana. Most fungal isolates exhibited their highest larval mortality rates seven days post-treatment at the temperatures of 25 and 27.5 °C. Some isolates caused considerably high larval mortality that exceeded 90% under specific temperature conditions. Overall, EPF showed great potential as bio-control agents for controlling larval populations of L. botrana. [Display omitted] • Entomogenous fungi showed great potential as biocontrol agents of Lobesia botrana. • Temperature significantly influenced all fungi on larval mortality of L. botrana. • An isolate from a cool region (Isaria fumosorosea EBAC01) was the most virulent. • Most fungal isolates demonstrated their highest efficacy at 25 and 27.5 °C. [ABSTRACT FROM AUTHOR]