The effect of 1-pentadecene on Tribolium castaneum behaviour: Repellent or attractant?

BACKGROUND

Movement of the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), in stored products is mediated by food volatiles and other semiochemicals.

RESULTS

In two-way olfactometer assays, T. castaneum was more attracted to wheat bran previously infested with conspecifics than to uninfested bran. Chemical analysis showed that 1-pentadecene was present in the headspace of T. castaneum-infested wheat bran, but not detectable in the headspace of uninfested bran. An olfactometer was used to test the effect on T. castaneum behaviour of 1-pentadecene, and of volatiles from wheat bran with and without 1-pentadecene. The lowest concentration of 1-pentadecene exhibited an attractive effect, compared to the control (n-hexane). Slightly higher concentrations showed a neutral effect, while the highest concentrations repelled T. castaneum. Wheat bran with a low 1-pentadecene concentration was more attractive than wheat bran alone, whereas higher concentrations of 1-pentadecene were repellent.

CONCLUSION

The results provide important information on intraspecific, semiochemical-mediated behaviour in T. castaneum, which could potentially be used to develop new methods to monitor the flour beetles in stored products. © 2021 Society of Chemical Industry.

New Steroidal 4-Aminoquinolines Antagonize Botulinum Neurotoxin Serotype A in Mouse Embryonic Stem Cell Derived Motor Neurons in Postintoxication Model

The synthesis and inhibitory potencies against botulinum neurotoxin serotype A light chain (BoNT/A LC) using in vitro HPLC based enzymatic assay for various steroidal, benzothiophene, thiophene, and adamantane 4-aminoquinoline derivatives are described. In addition, the compounds were evaluated for the activity against BoNT/A holotoxin in mouse embryonic stem cell derived motor neurons. Steroidal derivative 16 showed remarkable protection (up to 89% of uncleaved SNAP-25) even when administered 30 min postintoxication. This appears to be the first example of LC inhibitors antagonizing BoNT intoxication in mouse embryonic stem cell derived motor neurons (mES-MNs) in a postexposure model. Oral administration of 16 was well tolerated in the mouse up to 600 mg/kg, q.d. Although adequate unbound drug levels were not achieved at this dose, the favorable in vitro ADMET results strongly support further work in this series.

First Report of Anthracnose on Alfalfa Caused by Colletotrichum linicola in Serbia

Alfalfa (Medicago sativa L.) is economically the most important forage crop in Serbia. In July 2009, alfalfa plants showed symptoms characteristic of anthracnose disease ("shepherd's crook") including wilting and death of the upper portion of the stems. Anthracnose of alfalfa has been reported to be caused by Colletotrichum trifolii or C. destructivum (2). Alfalfa plants with anthracnose symptoms were collected in Srpska Crnja, South Banat District, Serbia. Infected tissue samples were surface disinfected with 5% sodium hypochlorite for 2 min and washed three times for 5 min in sterile distilled water. Surface sterilized tissue was transferred to sterile filter paper and placed on potato dextrose agar (PDA), and incubated at 24°C in the dark for 10 days (1). Developing colonies were light to dark olive green. In cultures on PDA medium, acervuli were formed. Conidia from acervuli were released in mucous masses that were orange to cream-pink in color. Conidia were hyaline, aseptate, straight with one end pointed and the other slightly rounded, measuring 12.5 to 25.0 × 2.5 to 7.5 μm (mean 19.83 × 4.42 μm). After 5 days, numerous setae were formed. The setae were slightly darker at the bottom and lighter at the top, septate with 3 septa. Setae dimensions were 100 to 185.5 × 2.5 to 5 μm (average 160.9 × 3.12 μm). The isolated fungus was designated Coll-44. Stems of 30 7-week-old plants were spray-inoculated in the laboratory with an aqueous suspension of conidia (10⁶ spores per ml; 10 ml per plant) harvested from 7-day-old cultures grown on PDA. The plants and two non-inoculated check plants were placed in a greenhouse and a covered with plastic bags at 25°C in darkness. After 48 h, plastic bags were removed from the all plants. All plants were watered once a day. Symptoms were observed 10 days after inoculation. No symptoms were observed on non-inoculated plants. In the greenhouse, all 30 inoculated plants became diseased with anthracnose symptoms after 10 days. Coll-44 was consistently re-isolated from diseased stem tissue. Koch's postulates were fulfilled by re-isolation from inoculated alfalfa plants. Pure culture of the Coll-44 isolate was deposited in the public collection of CBS-KNAW Fungal Biodiversity Centre, Utrecht, the Netherlands (specimen no. CBS 3263). Partial sequences of the internal transcribed spacer regions-ITS (GenBank Accession No. JX908364) and betatubulin-TUB2 gene (KJ556347) were amplified and sequenced from extracted fungal DNA with primer pairs ITS1-ITS4 (4) and T1-Bt2b (3), respectively. ITS sequence of the Coll-44 isolate showed 100% nucleotide identity to the GenBank accessions JQ005765 and AB046609 of C. linicola. TUB2 sequence of isolate Coll-44 showed 99.6% nucleotide identity with the GenBank accession JQ005849 of C. linicola isolate CBS 172.51. To our knowledge, this is the first report of C. linicola causing alfalfa anthracnose in Serbia. References: (1) A. P. Baxter et al. S. Afr. J. Bot. 2:259, 1983. (2) K. D. Hyde et al. Fungal Divers. 39:1, 2009. (3) K. O'Donnell and E. Cigelnik. Mol. Phylogenet. Evol. 7:103, 1997. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.