Fungal leaf mycota of selected aromatic plants in North Queensland

The phyllosphere, endophytic and pathogenic mycota of pepper, cinnamon and tumeric growing in close proximity in a tropical location were studied. Increasing washing cycles up to ten did not significantly alter the number of colonies recovered except in cinnamon which showed reduced numbers recovered beyond seven washes. The isolated fungi were both pathogenic and saprophytic. The fungal genera most frequently isolated from the plant samples by the spread plate method were Aspergillus, Cladosporium, Colletotrichum and Nigrospora. The leaf piece method of isolation most frequently recovered Cladosporium, Colletotrichum, Nigrospora, Pestalotiopsis, Phoma and nonsporing dematiaceous fungi. Three of these species isolated by the leaf piece method(Colletotrichum gloeosporioides on pepper, Pestalotiopsis cf. versicolor on cinnamon, and Phoma sp. on tumeric) are putative pathogens. The diversity of species isolated by washing was less than half that isolated by the leaf piece method. Recovery of species solely by the leaf piece plate method was presumably because these fungi were present primarily inside leaves rather than growing and fruiting abundantly on the leaf surface

Antifungal activity of selected aromatic and volatile oils and plant extracts on putative plant pathogens

A range of aromatic and volatile plant oils (0.1-3% concentration) were shown to inhibit spore germination of putative pathogens isolated from black pepper, cinnamon and\ud turmeric. Cinnamon and clove bark and leaf oils were more efficient inhibitors than the synthetic fungicide Amistar TM\ud used at recommended field concentrations. Cinnamon oils were\ud usually completely inhibitory of spore germination at low\ud concentrations. Garlic oil completely inhibited Phoma, but was less effective on all other fungal species. Oils of lemon grass leaf, lesser galangal rhizome, cardamom seed, and lemon myrtle leaf restricted spore germination at relatively high concentrations (0.5-1%). Lemongrass leaf oil completely inhibited spore germination of Pestalotiopsis cf. versicolor isolated from cinnamon leaves at all concentrations tested. Extracts from galangal rhizomes and cardamom leaves inhibited spore germination. Ethanol extracts had a greater ability to inhibit spore germination than corresponding water extracts. Ethanol extracts from galangal stem and cinnamon bark were particularly inhibitory. Meanwhile, cinnamon bark extract\ud tended to inhibit both putative pathogens and saprophytic fungi but it was less efficient on Pestaiotiopsis sp. isolated from cinnamon leaves

Survival of Aedes aegypti (Diptera, Culicidae) eggs in surface and subterranean breeding sites during the northern Queensland dry season

The effect of a protracted dry season on the viability of Ae. aegypti (L.) eggs was examined in Townsville, northern Queensland, Australia. Eggs were placed in several different surface and subterranean larval habitats; and after four dry season months, only 1-10% of eggs remained viable in the surface and subterranean sites, respectively. Low humidity and predation by Periplaneta americana (L.) were the major causes of egg mortality in eggs in surface sites. P. americana was the most significant cause of egg predation in subterranean breeding sites but fungi, especially Penicillium citrinum Thom, covered egg batches within 15 d. Mycotoxins produced by the spores of P. citrinum are believed to have killed embryonating eggs. The high mortality rate of Ae. aegypti eggs during the dry season suggests that this survival strategy is unlikely to contribute to rapid and successful recolonization of surface sites at the end of the wet season

Activity of some plant oils and extracts against Collectotrichum gloeosporioides

The antifungal effects of a range of plant extracts and oils were studied in a series of in vitro experiments against Colletotrichum gloeosporioides isolated from black pepper (Piper nigrum L.). Spore germination of the fungus was completely inhibited by cinnamon (Cinnamomum zeylanicum Blume.) oils as well as by water or ethanol extracts from galangal (Alpinia galanga L. Willd.) rhizomes and cardamom (Elettaria cardamomum Maton.) leaves. Ethanol extracts were more efficient in inhibiting spore germination than water extracts. Phytotoxicity symptoms were not observed or were minimal on pepper leaves and berries or red pepper fruits when treated with cardamom extract and galangal extract and a group of oils of cardamom, Eucalyptus, lesser galangal, lemon grass, lemon myrtle, neem, pepper black and tea-tree, but were pronounced with cinnamon oils. Cardamon oil was non toxic, but was required in higher concentrations to completely inhibit germination

Maintenance of fruit quality in organically-grown bananas under modified atmosphere conditions

The effects of modified atmosphere packaging at low storage temperature on the quality of organic bananas (cv. Cavendish) were investigated. Polybags, with or without an ethylene scavenger, significantly reduced (p<0.05) the total weight loss of bananas during storage for 25 days and fruit firmness was favoured by packaging. Bags containing a scavenger prevented the peel colour changing beyond the classification ‘greener than yellow’ over 25 days and total soluble solids were lower than in unwrapped fruit. The fruit was not treated with fungicide yet disease levels were relatively low at 25 days. Shelf life extension to 62 days was possible in polybags containing potassium permanganate when held at 14?C. When the scavenger was omitted, storage life was 55 days, yet acceptable taste and other quality were maintained

Mucor amphibiorum in the toad, Bufo marinus, in Australia

M. amphibiorum infection is reported in free-ranging toads, B. marinus , in Australia. In tissues the fungus occurred as spherules 4.9-36.4 micro m in diam; hyphae were not formed. Some spherules developed 2-11 daughter spherules internally and these were released into tissues by dissolution of the outer wall. Infected toads were found at 11 sites from 9 locations in northern and eastern Australia. The overall prevalence of infection in 3518 toads was 0.71%. At one location M. amphibiorum was isolated from soil

Bacterial flora from the gut of the wild and cultured banana prawn, Penaeus merguiensis

Aims: There is growing awareness of the influence of the bacterial composition of the gut on the health and growth of the host. This study compared the bacterial flora from the digestive system of the wild and cultured prawn, Penaeus merguiensis.\ud \ud Methods and Results: Whole guts were dissected from wild and cultured prawns and divided into sections corresponding to the foregut, digestive gland, midgut and hindgut. Homogenates of these sections were plated onto seawater nutrient agar and the colonies identified to genus level and, in some cases, species. Quantitative and qualitative comparisons amongst gut regions for both wild and cultured prawns are presented.\ud \ud Conclusions: Both wild and cultured prawns supported remarkably similar bacterial floral compositions, which included members from the genera Aeromonas, Plesiomonas, Photobacterium, Pseudoalteromonas, Pseudomonas and Vibrio. Members of the genus Vibrio were quantitatively dominant. A number of Vibrio species were recovered solely from cultured prawns. Of these, Vibrio gazogenes was the most notable (numerically dominating in all but the midgut). The opportunistic pathogen V. parahaemolyticus was also recovered.\ud \ud Significance and Impact of the Study: The remarkable similarity of gut compositions between wild and cultured prawns, despite being drawn from very different habitats, suggests an influence of the host on the establishment of the gut flora. An understanding of host/gut floral interactions has significance in fostering conditions which promote the growth of cultivated hosts

Fungal colonization of sago starch in Papua New Guinea

Sago starch is an important source of dietary carbohydrates in lowland Papua New Guinea. Over the past 30 years there have been sporadic reports of severe illness following consumption of sago starch. A common assumption is that fungal metabolites might be associated with the illness, leading to the need for a more thorough investigation of the mycoflora of sago starch. Sago starch was collected from areas of high sago consumption in Papua New Guinea for fungal analysis (69 samples). Storage methods and duration were recorded at the time of collection and pH on arrival at the laboratory. Yeasts were isolated from all samples except two, ranging from 1.2 × 103 to 8.3 × 107 cfu/g. Moulds were isolated from 65 of the 69 samples, ranging from 1.0 × 102 to 3.0 × 106 cfu/g. Of 44 samples tested for ergosterol content, 42 samples showed the presence of fungal biomass. Statistical analyses indicated that sago starch stored for greater than five weeks yielded significantly higher ergosterol content and higher numbers of moulds than sago stored for less than five weeks. The method of storage was also shown to influence mould numbers with storage in natural woven fibre containers returning significantly greater numbers than present in other storage methods tested. Potentially mycotoxigenic genera of moulds including Aspergillus and Penicillium were commonly isolated from sago starch, and as such storage factors that influence the growth of these and other filamentous fungi might contribute to the safety of traditional sago starch in PNG

Mucor amphibiorum in the toad, Bufo marinus, in Australia

M. amphibiorum infection is reported in free-ranging toads, B. marinus , in Australia. In tissues the fungus occurred as spherules 4.9-36.4 micro m in diam; hyphae were not formed. Some spherules developed 2-11 daughter spherules internally and these were released into tissues by dissolution of the outer wall. Infected toads were found at 11 sites from 9 locations in northern and eastern Australia. The overall prevalence of infection in 3518 toads was 0.71%. At one location M. amphibiorum was isolated from soil