Avoidance tests with Folsomia candida for the assessment of copper contamination in agricultural soils.

The feasibility of assessing copper accumulation in agricultural soils using avoidance tests with a Canadian strain of Folsomia candida was investigated under laboratory conditions. The avoidance response to nominal copper sulfate concentrations of 0, 200, 800, 1600 and 3200 mg kg⁻¹ in OECD soil was inconsistent between trials with the standard plastic cup or a modified Petri dish method requiring less soil. However, combined results from three Petri dish trials decreased variability and provided a 75% avoidance level, close to the 80% criterion proposed for avoidance tests. A Copper avoidance EC50s of 18 mg kg⁻¹ was obtained using the Petri dish method whether tests were conducted with or without light. While Petri dish tests have potential as a cheap tool to distinguish metal contaminated soils from uncontaminated soils they would be unsuitable for tracking or quantifying changes in metal concentrations. throughout remediation. Advantages and limitations of the method have been presented.

Wind as an abiotic factor of Colorado potato beetle (Coleoptera: Chrysomelidae) flight take-off activity under field conditions.

The flight take-off activity of Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was significantly higher at a landscape-protected than at semiexposed and exposed sites in a 2-yr field study. In both years, mean daylight temperature, solar radiation, and relative humidity were generally similar at all sites, but wind speed was lower at the protected site than at the exposed sites. Results suggest that wind was the limiting abiotic factor for flight take-off at the exposed site. Caged beetles exposed to constant wind speeds of 3.4, 4.7, and 7.0 m/s showed a significant corresponding decrease in number of flight take-off. There was no cumulative effect of wind exposure on the readiness of the beetles to fly, suggesting that wind acts as a physical barrier to flight take-off. It should be possible to reduce Colorado potato beetle flight dispersal by selecting fields most exposed to wind over landscape-protected fields when rotating potato, Solanum tuberosum L., crops.