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Phosphine (PH3) and ethyl formate (EF), the two popular fumigant disinfectants of stored product insect pests, are primarily evaluated for their knock down effects without considering their post-fumigation sub-lethal activities. The sub-lethal activities (adult survivorship, fecundity, sterility and female sex pheromone production) of the fumigants were evaluated on a field-to-storage insect pest adzuki bean beetle, Callosobruchus chinensis (L.). The adults' survivorship and female fecundity, both were dose-dependently affected by sub-lethal PH3 and EF fumigation exposures. Hatchability of the eggs laid by fumigated female adults were also significantly affected. Gas-chromatography mass-spectrometry analysis of solid-phase micro-extraction from virgin fumigated C. cinensis females revealed that the PH3 LC25 (the lethal concentration required to kill the 25% of the population) fumigated female C. chinensis released significantly less amount of the pheromone components. In contrast, EF LC25 exposure did not affect the pheromone release. This study unveils the facts that the EF and PH3 fumigation have detrimental bioactivities against C. chinensis. Notably, this suggests to consider the sub-lethal EF and PH3 fumigation rather than the dose required to instantly kill all the C. chinensis individuals for disinfestation of stored adzuki bean. [ABSTRACT FROM AUTHOR]

Endophytic bacteria, a rich source of bioactive secondary metabolites, are ideal candidates for environmentally benign agents. In this study, an endophytic strain, Streptomyces sp. AE170020, was isolated and selected for the purification of nematicidal substances based on its high nematicidal activity. Two highly active components, aureothin and alloaureothin, were identified, and their chemical structures were determined using spectroscopic analysis. Both compounds suppressed the growth, reproduction, and behavior of Bursaphelenchus xylophilus. In in vivo experiments, the extracts of strain Streptomyces sp. AE170020 effectively suppressed the development of pine wilt disease in 4-year-old plants of Pinus densiflora. The potency of secondary metabolites isolated from endophytic strains suggests applications in controlling Bursaphelenchus xylophilus and opens an avenue for further research on exploring bioactive substances against the pine wood nematode. [ABSTRACT FROM AUTHOR]

Metarhizium anisopliae is a promising alternative to chemical pesticides against pine wilt disease caused by Bursaphelenchus xylophilus. Herein, we investigated the efficacy of modified atmosphere packaging (MAP) to prolong the shelf-life of the M. anisopliae conidia. The effects of various conditions on its stability were also examined. M. anisopliae-inoculated millet grains were treated in a MAP system with different packaging materials (polypropylene, PP; polyethylene terephthalate, PET; ethylene vinyl alcohol, EVOH), gas compositions (high CO2 atmosphere, ≈ 90%; high O2 atmosphere, > 95%; high N2 atmosphere, > 95%; 30% CO2 + 70% N2; 50% CO2 + 50% N2; 70% CO2 + 30% N2), and storage temperatures (4 and 25 °C). Results revealed EVOH film as the best for the preservation of gases at all concentrations for 28 days. MAP treatment in the high-barrier EVOH film under an atmosphere of 30% CO2 + 70% N2 achieved 80.5% viability of dried conidia (7.4% moisture content), with 44.2–64.9% viability recorded with the other treatments. Cold storage for technical concentrates formulation promoted extension of shelf-life of MAP-treated conidia. These results imply that MAP under optimized conditions could enhance the shelf-life of fungus-based biopesticides in fungus-colonized substrates formulations. [ABSTRACT FROM AUTHOR]

Avermectin, produced by Streptomyces avermitilis, is an active compound protective against nematodes, insects, and mites. However, its potential usage is limited by its low aqueous solubility. The uridine diphosphate (UDP)-glycosyltransferase (BLC) from Bacillus licheniformis synthesizes avermectin glycosides with improved water solubility and in vitro antinematodal activity. However, enzymatic glycosylation of avermectin by BLC is limited due to the low conversion rate of this reaction. Thus, improving BLC enzyme activity is necessary for mass production of avermectin glycosides for field application. In this study, the catalytic activity of BLC toward avermectin was enhanced via directed evolution. Three mutants from the BLC mutant library (R57H, V227A, and D252V) had specific glucosylation activity for avermectin 2.0-, 1.8-, and 1.5-fold higher, respectively, than wild-type BLC. Generation of combined mutations via site-directed mutagenesis led to even further enhancement of activity. The triple mutant, R57H/V227A/D252V, had the highest activity, 2.8-fold higher than that of wild-type BLC. The catalytic efficiencies (Kcat/Km) of the best mutant (R57H/V227A/D252V) toward the substrates avermectin and UDP-glucose were improved by 2.71- and 2.29-fold, respectively, compared to those of wild-type BLC. Structural modeling analysis revealed that the free energy of the mutants was − 1.1 to − 7.1 kcal/mol lower than that of wild-type BLC, which was correlated with their improved activity. Key points: • Directed evolution improved the glucosylation activity of BLC toward avermectin. • Combinatorial site-directed mutagenesis led to further enhanced activity. • The mutants exhibited lower free energy values than wild-type BLC. [ABSTRACT FROM AUTHOR]

Schisandra chinensis, Lycium chinense, and Cornus officinalis are cultivated in South Korea, China and Japan. Because of their beneficial biological effectiveness, the consumption of these herbs is increasing. The objective of this study was to analyze the pesticide residue levels on these herbal fruits produced in Korea. A short- and long-term risk assessment of the pesticides in herbal fruits was conducted. Pesticides were detected in most samples, and all samples with multiple residues were also noted. The average numbers of pesticides detected in the S. chinensis, L. chinense, and C. officinalis samples were 1.84, 10.28, and 5.87, respectively. The short-term and highest long-term risks, and the cumulative risk (cHI) were 0.633%, 1.14%, and 7.56% (S. chinensis), 1.0 × 10−1%, 1.1 × 10−5%, and 4.0 × 10−5% (L. chinense), and 2.2 × 10−5%, 1.6 × 10−5%, and 8.9 × 10−5% (C. officinalis). No significant health risk for consumers via herbal fruit consumption was detected. [ABSTRACT FROM AUTHOR]

Long-range sex pheromones are generally considered to be a main cue for mate recognition in the order Hymenoptera. Although considerable attention has been given to the identification of semiochemicals in the superfamily Chalcidoidea, which comprises 19 families, no study has identified active components in a field bioassay. We herein report the sensitive and selective pheromone communication system of the Korean apricot wasp, Eurytoma maslovskii (Eurytomidae), whose larvae feed on Prunus mume seeds. Using gas chromatography coupled with electroantennographic detection (GC-EAD) and mass spectrometry (GC-MS), we detected 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate in thoracic extracts of female E. maslovskii at a ratio of 8:2 as the active pheromone components. Field experiments showed that the attractive effect of the two compounds is highly enantioselective. Racemic 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate were not attractive to E. maslovskii males. In bioassays with single enantiomers, the (2 S,10 R)-enantiomer was highly attractive to male wasps, and the (2 S,8 S)-enantiomer was also attractive, although to a lesser degree. No synergistic effect between (2 S,10 R)- and (2 S,8 S)-enantiomers was identified, and the (2 S,10 R)-enantiomer alone caught significantly more males than the natural pheromone extracts. The addition of other enantiomers to the (2 S,10 R)-isomer significantly decreased the attraction of conspecific males. In addition, a very low dose of synthetic pheromone attracted conspecific males, showing that both female signaling and male response traits may have evolved to contribute to species-specific sexual communication in this species. [ABSTRACT FROM AUTHOR]

Control efficacy of sandalwood oil ( Santalum austrocaledonicum Vieill) and its main components, α- and β-santalol, which have not been tested before against Aphis gossypii Glover (Hemiptera:Aphididae), was investigated in the laboratory, greenhouse and field bioassays. The main constituents of the commercial sandalwood oil were found to be α-santalol (47.5 %), β-santalol (18.7 %), bergamotol (7.2 %) and lanceol (9.1 %) according to GC and GC-MS analyses. The sandalwood oil was fractionated into an α-santalol-rich fraction (RF), β-santalol RF, and a mixture of α- and β-santalols by silica gel column chromatography. The purity of α-santalol RF was 75.4 % (ratio of α-:β-santalol was 94:6) and that of β-santalol RF was 34.6 % (ratio of α-:β-santalol was 16:84). Laboratory bioassay showed that sandalwood oil, α- and β-santalol RFs had the same and significantly higher repellency and control efficacy against A. gossypii than the two control treatments and that a mixture of α- and β-santalols was toxic to the aphid. Santalol was comparable to imidacloprid (a neonicotinoid insecticide) in its efficacy against A. gossypii infesting Rose of Sharon, Hibiscus syriacus L., with 98.8 % mortality. The control efficacies of sandalwood oil (94.0 %), α-santalol RF (84.2 %), β-santalol RF (90.6 %) and a mixture of α- and β-santalols (88.7 %) against the A. gossypii infesting hot peppers were also comparable to each other in the greenhouse bioassay. Considering its control efficacy against A. gossypii, the application of sandalwood oil and its components may open the possibility of environmentally friendly management of A. gossypii. [ABSTRACT FROM AUTHOR]

The sex pheromone of Stathmopoda masinissa Meyrick, an important pest of persimmon fruit in East Asia such as Korea, China, and Japan, was investigated. A lure using ( E4, Z6)-4,6-hexadecadienyl acetate (E4,Z6-16Ac), which was identified as a sex pheromone compound of Japanese population, did not work at all for Korean population. Therefore, components in the abdominal extract of the moth were identified and their attractiveness was evaluated in the field. Two components, E4,Z6-16Ac and ( E4, Z6)-4,6-hexadecadien-1-ol (E4,Z6-16OH) were identified from the extract of female abdominal extract in a ratio of 10-15:90-85 by GC-MS analysis with synthetic standards. E4,Z6-16Ac and E4,Z6-16OH were previously identified as EAG-active components of this moth in Japanese population. However, ( E4, Z6)-4,6-hexadecadienal (E4,Z6-16Ald), which is one of the abdominal extract components and EAG-active component in Japanese population, was not detected in our samples. In the persimmon orchard, single component of E4,Z6-16Ac or E4,Z6-16OH was not attractive. However, the 1:1 mixture of the two components significantly increased the captures of male S. masinissa. Interestingly, traps baited with E4,Z6-16Ac captured significantly higher number of Oedematopoda ignipicta (Lepidoptera: Stathmopodidae) than the traps baited with E4,Z6-16OH or blend of the two components. The attractiveness of E4,Z6-16Ac to O. ignipicta is a new finding. [ABSTRACT FROM AUTHOR]

Apolygus spinolae (Meyer-Dür) (Heteroptera: Miridae) is an important pest of fruit and tea trees in Korea and Japan. Analyses of extracts of metathoracic scent glands revealed that those of female bugs contained hexyl butyrate, ( E)-2-hexenyl butyrate, and ( E)-4-oxo-2-hexenal in a ratio of 20:100:7. The glands of males contained the same three compounds, but the ratio of the components was quite different, with hexyl butyrate being the most abundant. Field trapping tests with various blends of the synthetic compounds dispensed from high-density polyethylene tubes showed that ( E)-2-hexenyl butyrate and ( E)-4-oxo-2-hexenal were essential for attraction of male A. spinolae, and catches with a wide range of ratios of these two compounds did not differ significantly. However, adding hexyl butyrate at 50 % or more of the ( E)-2-hexenyl butyrate to the binary blend strongly inhibited attraction of males. Trap catches increased with increasing amounts of a 10:1 blend of ( E)-2-hexenyl butyrate and ( E)-4-oxo-2-hexenal from 0.011 to 11 mg loaded into the tube. Catches of males in traps baited with lures containing 1.1 mg of the binary blend were not significantly different from catches in traps baited with live virgin females. [ABSTRACT FROM AUTHOR]

Riptortus pedestris F. [= R. clavatus (Thunberg)] is one of the most serious pests affecting the cultivation of sweet persimmon, which is one of the most important export fruits in Korea. A pheromone-baited trap has been used in attempts to control this pest. In this study, the development of a more efficient pheromone-baited trap for R. pedestris was pursued by investigating three different shapes of traps: the fish trap, the pyramidal trap, and the symmetry trap. The fish trap, which is the only one commercially available, captured the lowest number of R. pedestris, and the pyramidal trap showed moderate capture efficacy. The symmetry trap captured significantly greater numbers of R. pedestris adults (ca. 6 and 28 times more than the pyramidal and fish trap, respectively). Significantly increased trapping efficacy of the symmetry trap would be useful for mass trapping of R. pedestris. [ABSTRACT FROM AUTHOR]