Decay of Cryptosporidium parvfum DNA in cowpats in subtropical environments determined using qPCR

Cryptosporidium oocysts pose a significant threat to public health due to its ability to contaminate environmental waters, leading to outbreaks of waterborne diseases and emphasizing the crucial need for effective water treatment and monitoring systems. This study aimed to investigate the decay of Cryptosporidium oocyst DNA in cow fecal matter under different environmental conditions prevalent in sub-tropical Southeast Queensland (SEQ) during summer and winter seasons. The effects of ambient sunlight and shaded conditions on the decay rates of C. parvum DNA in cow fecal samples were evaluated. The results showed that measurable levels of C. parvum DNA were observed for up to 60 days during the summer experiments, with a slower decay rate on the surface (k = -0.029) and sub-surface (k = -0.043) of the cowpat under shaded conditions than those on the surface (k = -0.064) and sub-surface (k = -0.079) under sunlight conditions. The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower (p = 0.004; p = 0.004) than those on the surface and sub-surface under sunlight conditions during summer experiments. During the winter treatments, measurable levels of C. parvum DNA were observed for up to 90 days, and the decay rates were slower on the surface (k = -0.036) and sub-surface (k = -0.034) of the cowpat under shaded conditions than those under sunlight conditions (k = -0.067 for surface and k = -0.057 for sub-surface). The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower than those on the surface (p = 0.009) and sub-surface (p = 0.041) under sunlight conditions during winter experiments. Moreover, the decay rate in the summer sunlight surface treatment (k = -0.064) was significantly faster from those in the winter shaded surface (k = -0.036; p = 0.018) and sub-surface (k = -0.034; p = 0.011) treatments. Similar results were also observed for summer sunlight sub-surface (k = -0.079), which was significantly faster than winter shaded surface (k = -0.036; p = 0.0008) and sub-surface (k = -0.034; p = 0.0005) treatments. Overall, these findings are important to enhance our understanding on the degradation of C. parvum DNA in cow fecal matter in SEQ, particularly in relation to seasonal variations and environmental conditions.

Comparison of emergence traps of different shape and translucency in the trapping of Culicoides (Diptera: Ceratopogonidae)

Various types of emergence traps are available for investigations of the breeding habitats of Culicoides (Diptera: Ceratopogonidae). In order to assess the potential impact of the trap design on the trapping success, we compared the efficiency of opaque and white (more translucent) emergence traps and two trap shapes (cone-shaped and quadratic), to sample Culicoides emerging from cowpats. Significantly higher numbers of Culicoides chiopterus and Culicoides dewulfi were trapped with opaque traps, while there was no obvious effect of the trap shape. There were no distinct differences in the microclimate among different trap types.

Impact of experimental flooding on larvae and pupae of dung-breeding Culicoides

Culicoides biting midges (Diptera: Ceratopogonidae) spend the greatest part of their life in the larval stage. However, knowledge on the immature stages and the impact of abiotic factors on their development is still poor. Therefore, we investigated the effect of flooding on the larvae and pupae of Culicoides chiopterus (Meigen, 1830) and C. dewulfi Goetghebuer, 1936. In water, the larvae of both species showed head-to-tail flexions and sinuous flexions, at slow rates, but were not able to swim. Flooding of larvae for 24 h did not affect the number of emerging adults; flooding of pupae significantly reduced the emergence rate of C. chiopterus, compared to the control group, while C. dewulfi was not affected. Pupae were not able to float and no pupae survived flooding for 10 days. After flooding of larvae for 10 days, 50 % of C. chiopterus and 4 % of C. dewulfi completed the pre-adult development. During this treatment, 84 % of C. chiopterus and 48 % of C. dewulfi larvae pupated in water.