Basidiosins A and B: Cyclopentapeptides from the entomophthoralean fungus Basidiobolus meristosporus.

Two new cyclopentapeptides, basidiosins A and B (1 and 2) were isolated from the mycelia extracts of entomophthoralean fungus Basidiobolus meristosporus RCEF 4516. The structures were determined based on spectroscopic methods, and the absolute config urations were assigned by Marfey's method on their acid hydrolyzates. Compounds 1 and 2 were identified as cyclo(L-Thr-L-Leu- L-Ile-D-Tyr-D-Thr) and cyclo(L-Thr-L-Leu-L-Val-D-Val-D-Ser), respectively. They were evaluated for the biological activities including antibacterial, antifungal and antioxidative activities. Furthermore, the biosynthetic pathway of 1 was proposed by bioinformatic analysis. This is the first study on the isolation of natural products from Basidiobolus fungus.

A floatable formulation and laboratory bioassay of Pandora delphacis (Entomophthoromycota: Entomophthorales) for the control of rice pest Nilaparvata lugens Stål (Hemiptera: Delphacidae).

BACKGROUND: The brown planthopper (BPH), Nilaparvata lugens (Staparvata luera: Delphacidae), is a serious rice pest that easily develops resistance to chemical insecticides and resistant rice varieties. This study evaluated the infectivity of the BPH fungal pathogen, Pandora delphacis, and developed a novel formulation as an alternative means of BPH control. RESULTS: In a multiconidial concentration bioassay, P. delphacis-infected BPH cadavers were observed on day 4, but most occurred between days 5 and 8. BPH mortality depended on the inoculated conidial concentration. The cumulative mortality of adult BPHs reached 81.7% at 192 conidia mm(-2) in 8 days. Inoculation with 40.9 conidia mm(-2) was sufficient to induce 50% BPH death, based on analysis of a time-concentration-mortality model. A floatable P. delphacis-based formulation was made for use in paddy fields; mycelium-containing pellets mimicking mycosed cadavers could produce 7-15.7 × 10(4) infectious conidia pellet(-1) at 11-28 °C. In the laboratory bioassay, three floating pellets in a BPH-rearing jar caused 75.5% BPH mortality within 8 days, similar to the mortality level caused by direct conidial inoculation. CONCLUSION: P. delphacis is a potential biocontrol agent of BPHs for further research, and the novel floatable formulation holds promise as a method for BPH control.

Effects of cryopreservation at -80 degrees C on the formulation and pathogenicity of the obligate aphid pathogen Pandora nouryi.

Cryopreservation at -80 degrees C is an alternative to liquid nitrogen storage for Entomophthorales. However, detailed studies about its effects on fungal pathogenicity and formulation are very limited. In the present study, the obligate aphid pathogen Pandora nouryi was formulated as mycelia grown on millet-gel granules after preservation as primary spores at -80 degrees C for 3-18 months, although its ability to produce infectious conidia gradually diminished. The sporulation capacity of this granular formulation was reduced to 18.5 x 10(4) conidia/mg after 18 months of storage, which was still higher than that of mycotized aphids. The half-decline time of sporulation capacity was computed as 13.6 months. The infectivity to the green peach aphid Myzus persicae had no significant decline in 12 months. The ability to yield resting spores within host carcasses remained unchanged, and the probability of resting spore formation increased with the conidial concentrations that infect aphids. Therefore, cryopreservation at -80 degrees C exerted a marginal impact on formulation and pathogenicity of P. nouryi and can substitute for costly liquid nitrogen storage in routine laboratory studies. The potential of the formulation in aphid biocontrol can be maintained although there is a risk of losing fungal sporulation ability in long-term preservation.

[Effect of drying and temperature on the sporulation of Pandora delphacis mycelia gelatinized].

The entomophthoraceous fungus, Pandora delphacis, is a microbial agent highly potential for control of sucking-type insects. In this study, effort was made of gelatinizing the mycelia of the isolate F95129 from submerged culture using polyacrylamide-starch gel pwder and sodium alginate. The resulting film-like gel of the mycelia sporulated very well, indicating that the materials used for gelatinization of the mycelia was biologically compatible with P. delphacis. Then, the gelatinized mycelia were slowly dried in silica chamber at 4, 14, and 24 degrees C, respectively. After 35-day drying and storage in the chamber, however, a 22.7%-92.8% decrease of sporulation capacity occurred in the film-like gels, which then had different water content. The nutrient-supplemented polyacrylamide-starch gel stored at 14 degrees C with water content of 6.1%-7.4% was best for largely decreasing the loss of sporulation capacity among the combinations of gel, nutrition, water content and temperature. The results indicate that it could be possible to choose a desirable gel for longer biological activity of gelatinized P. delphacis mycelia.