Dose-response analysis of Bacillus thuringiensis HD-1 cry- spore reduction on surfaces using formaldehyde with pre-germination.

AIM: To establish a basis for rapid remediation of large areas contaminated with Bacillus anthracis spores. METHODS AND RESULTS: Representative surfaces of wood, steel and cement were coated by nebulization with B. thuringiensis HD-1 cry- (a simulant for B. anthracis) at 5.9 ± 0.2, 6.3 ± 0.2 and 5.8 ± 0.2 log10 CFU per cm2 , respectively. These were sprayed with formaldehyde, either with or without pre-germination. Low volume (equivalent to ≤2500 L ha-1 ) applications of formaldehyde at 30 g l-1 to steel or cement surfaces resulted in ≥4 or ≤2 log10 CFU per cm2 reductions respectively, after 2 h exposure. Pre-germinating spores (500 mmol l-1 l-alanine and 25 mmol l-1 inosine, pH 7) followed by formaldehyde application showed higher levels of spore inactivation than formaldehyde alone with gains of up to 3.4 log10 CFU per cm2 for a given dose. No loss in B. thuringiensis cry- viability was measured after the 2 h germination period, however, a pre-heat shock log10 reduction was seen for B. anthracis strains: LSU149 (1.7 log10), Vollum and LSU465 (both 0.9 log10), LSU442 (0.2 log10), Sterne (0.8 log10) and Ames (0.6 log10). CONCLUSIONS: A methodology was developed to produce representative spore contamination of surfaces along with a laboratory-based technique to measure the efficacy of decontamination. Dose-response analysis was used to optimize decontamination. Pre-germinating spores was found to increase effectiveness of decontamination but requires careful consideration of total volume used (germinant and decontaminant) by surface type. SIGNIFICANCE AND IMPACT OF THE STUDY: To be practically achievable, decontamination of a wide area contaminated with B. anthracis spores must be effective, timely and minimize the amount of materials required. This study uses systematic dose-response methodology to demonstrate that such an approach is feasible.

Volatilisation of pesticides under field conditions: inverse modelling and pesticide fate models.

BACKGROUND: A substantial fraction of the applied crop protection products on crops is lost to the atmosphere. Models describing the prediction of volatility and potential fate of these substances in the environment have become an important tool in the pesticide authorisation procedure at the EU level. The main topic of this research is to assess the rate and extent of volatilisation of ten pesticides after application on field crops. RESULTS: For eight of the ten pesticides, the volatilisation rates modelled with PEARL (Pesticide Emission Assessment at Regional and Local scales) corresponded well to the calculated rates modelled with ADMS (Atmospheric Dispersion Modelling System). For the other pesticides, large differences were found between the models. Formulation might affect the volatilisation potential of pesticides. Increased leaf wetness increased the volatilisation of propyzamide and trifloxystrobin at the end of the field trial. The reliability of pesticide input parameters, in particular the vapour pressure, is discussed. CONCLUSION: Volatilisation of propyzamide, pyrimethanil, chlorothalonil, diflufenican, tolylfluanid, cyprodinil and E- and Z-dimethomorph from crops under realistic environmental conditions can be modelled with the PEARL model, as corroborated against field observations. Suggested improvements to the volatilisation component in PEARL should include formulation attributes and leaf wetness at the time of pesticide application. © 2015 Society of Chemical Industry.