Larvicidal activity of metabolites from the endophytic Podospora sp. against the malaria vector Anopheles gambiae

In a screening for natural products with mosquito larvicidal activities, the endophytic fungus Podospora sp. isolated from the plant Laggera alata (Asteraceae) was conspicuous. Two xanthones, sterigmatocystin (1) and secosterigmatocystin (2), and an anthraquinone derivative (3) 13-hydroxyversicolorin B were isolated after fermentation on M2 medium. These compounds were characterised using spectroscopic and X-ray analysis and examined against third instar larvae of Anopheles gambiae. The results demonstrated that compound 1 was the most potent one with LC50 and LC90 values of 13.3 and 73.5 ppm, respectively. Over 95% mortality was observed at a concentration 100 ppm after 24 h. These results compared farvourably with the commercial larvicide pylarvex® that showed 100% mortality at the same concentration. Compound 3 was less potent and had an LC50 of 294.5 ppm and over 95% mortality was achieved at a concentration of 1,000 ppm. Secosterigmatocystin (2) revealed relatively weak activity and therefore LC values were not determined

Isolation of diverse viable fungi from the larvae of the introduced chironomid Eretmoptera murphyi on Signy Island

The chironimid midge Eretmoptera murphyi has been introduced to Signy Island and has since become established at a single site. Viable propagules of a diverse range of micro-fungi were recovered from the normal intestinal tract of larvae of E. murphyi, indicating the potential for the larvae to act as vectors for fungal introductions. The fungi present in the intestines of the larvae included ascomycetes, zygomycetes and an oomycete, and this diversity highlights the potential for multiple microbial introductions from a single invertebrate introduction