The effect of temperature and relative humidity on wound healing and infection of potato tubers byAlternaria solani

Under environmental conditions favorable for wound healing, potato tubers became significantly (P = 0.05) more resistant toA. solani infection during a two-day interval between wounding and inoculation. This period coincided with the time required for wounded tubers to completely seal wounded surfaces by suberization at 15.6°C/98% RH. Suberization of the wounded surfaces provided tubers significant (P = 0.05) protection againstA. solani invasion but wound periderm development was also essential for total exclusion of the pathogen. Wound healing takes place faster at high temperatures and relative humidities. The effect of temperature is more critical in the wound healing process.     

The presence and location ofErwinia carotovora subsp.carotovora (Jones) Bergey et al. in the gut of adultDrosophila melanogaster (Meigen)

The potato blackleg bacteriumErwinia carotovora subsp.carotovora (Jones) Bergey et al. was found in feces and regurgitated material obtained from surface sterilized adult fruit flies,Drosophila melanogaster (Meigen), that had fed for five hours on nutrient agar cultures of the bacterium. The highest levels of bacteria were obtained from fecal material and it is likely that this is the source of most of the inoculum carried by these vectors. The bacteria were found to be present in the foregut, midgut, and hindgut ofD. melanogaster. The largest number of bacteria were in the foregut with the population level decreasing as distance down the digestive tract increased. It is probable that the association between the vector and the bacterium is accidental. The probability that the insect aids survival of the bacterium by protecting it from adverse environmental conditions is suggested.     

The prevalence of <Emphasis Type="Italic">Mycobacterium bovis</Emphasis>-infection and atypical mycobacterioses in cattle in and around Morogoro,Tanzania

A study was conducted to determine the prevalence of Mycobacterium bovis-infection and atypical mycobacterioses in different cattle herd management systems in and around Morogoro, Tanzania. Between April and June 2005, a total of 728 bovines from 49 herds were tested for M. bovis-infection and atypical mycobacterioses. Milk samples were taken from tuberculin positive animals and analysed for the presence of mycobacteria. Total prevalences of 2.5% and 10.1% were found for M. bovis-infection and atypical mycobacterioses respectively, with more M. bovis-infection in cattle in the extensive management system and more atypical mycobacterioses in cattle in the intensive management system. From 8 out of 42 milk samples (19%) atypical mycobacteria were cultured. A higher prevalence of M. bovis-infection in the extensive sector could be due to several factors. In addition, such high prevalence puts herd owners and their families at risk for BTB. Therefore control of BTB, as well as education of cattle owners is important, especially in the extensive sector.