Effects of organophosphate and synthetic pyrethroid sheep dip formulations on protozoan survival and bacterial survival and growth

Abstract

Sheep dipping with organophosphate or synthetic pyrethroid-based formulations is still widely used by farmers in the UK to control ectoparasites and results in 175-220 million litres of spent sheep dip produced each year. Spent sheep dip may be diluted in animal slurry or water prior to disposal onto land. However, the effects of this practice on the microbial ecology of animal slurries, soil and aquatic systems are still relatively unknown. This paper investigated the effect of Bayticol (synthetic pyrethroid sheep dip) and Ectomort (organophosphate sheep dip) concentrations on (i) the survival of 15 protozoan species, (ii) the recovery of the four species of amoebae, and (iii) bacterial survival and growth. This investigation found that overall Bayticol was less toxic to protozoa than Ectomort, with minimum inhibitory concentrations ranging from 0.01 to 0.03% (v/v) and 0.005 to 0.06% (v/v), respectively. Amoebic cysts remained viable and emerged from dormancy, thereby pointing to the potential for recovery of protozoan communities in contaminated environments. The presence of sheep dips did not affect bacterial survival and growth on agar; however, the five test bacteria were not able to utilise the sheep dips as sole carbon sources. These findings have implications for the contamination of animal slurries, soil and aquatic systems, in that there is the potential for significant increases in microbial numbers, containing putative pathogens due to the diminution of bacteriophagous protozoan populations.

Resistance and resilience responses of a range of soil eukaryote and bacterial taxa to fungicide application

“…Such organisms are integral members of soil food webs as both predators and prey and their activities are beneficial to nutrient cycling within the soil ( Mikola et al, 2002 ), with the potential to impact plant growth ( Bonkowski, 2004 ). Culture-dependent methods have previously shown impacts of pesticides on non-target eukaryotic microorganisms in soils ( Ekelund, 1999; Ekelund et al, 2000; Boucard et al, 2004 ). However, such studies are limited by the fact that only a small percentage of soil microorganisms are culturable ( Janssen et al, 2002 ).…”

Biodegradation of Chlorpyrifos and Its Hydrolysis Product 3,5,6-Trichloro-2-Pyridinol by a New Fungal Strain Cladosporium cladosporioides Hu-01

“…Previous reports revealed that a wide range of water and terrestrial ecosystems have been contaminated with chlorpyrifos [15]–[17]. Moreover, much evidence suggests that chlorpyrifos may affect the endocrine system, respiratory system, cardiovascular system, nervous system, immune system, as well as the reproductive system due to its high mammalian toxicity [18]–[27].…”

A comparison of the growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis in the presence of suspended and attached Escherichia coli K12

“…the motile trophozoite, the 'floating form', and the much smaller cyst (Page, 1988), but a fourth form, known as a 'round body', has also been reported (Band, 1963;Griffiths, 1970;Weisman, 1976). The lack of pseudopodia on the round body results in a cessation of movement and feeding (McConnachie, 1969;Griffiths, 1970), and it is a transient form that, in naked amoebae, leads to cyst formation under conditions of starvation, osmotic stress, anaerobiasis, or treatment with chemicals (Band, 1963;Neff et al, 1964;Griffiths & Hughes, 1969;Weisman, 1976;Lasman, 1987;Turner et al, 1997;Boucard et al, 2004). The round bodies of the social amoeba Dictyostelium discoideum can revert back to active trophozoites if nutrients are replenished (Yarger et al, 1974), but no corresponding data exist for naked amoebae.…”