Determining soil effects on SHB pupation

Ellis et al. (2004c) determined the impact of soil type, moisture, and density of SHB pupation success see section The methods they used are applicable to any study focusing on pupation habits of SHBs.

  1. Autoclave test soils prior to use to kill pathogens.
  2. The soil moisture can be manipulated by first drying the soil in an oven.
    2.1. Spread the soil in a shallow, metal tray to facilitate drying. The drying oven can be set to 85°C. The soil is “dry” when the tray holding the soil no longer loses weight over a 24 h period. This takes 6 weeks or longer at 85°C. If decomposition of organic soil compounds is of concern to the research, the soils can be dried at lower temperatures for longer periods of time.
    2.2. Measure soil moisture as water by weight (either a dry mass or wet mass basis). For the dry mass gravimetric method, soil moisture = grams of water/grams of dry soil.
    2.3. Using this formula, create soils of various moistures by first drying the soil as outlined above, weighing it, and then adding an appropriate amount of distilled water to create the desired water by weight moisture level.
  3. For each soil type of interest, place a desired amount of loose soil into plastic pupation containers (pupation chambers are better if they are tall rather than wide).
    Ellis et al. (2004c) used cylindrical containers that were ~22 cm in height and 1,000 ml in volume. The containers should have small holes drilled in the bottom to allow water to exit.
  4. Compact the soil while in the pupation chamber if soil density is an important component of the study.
    4.1. Run 1 l of distilled water through the soil-filled pupation container.
    The holes in the bottom of the container will allow the water to drain. The water compacts the soil naturally.
    4.2. If a predetermined amount of water by weight is desired in the packed soil, dry the packed soil while in the pupation container.
    The oven must be set at a temperature that does not melt or distort the plastic container, or decompose soil compounds/nutrients (for the microbes, not the beetles themselves) if that is of interest. The container of soil must remain in the oven until it no longer loses weight over a 24 h period.
    4.3. Add the appropriate amount of distilled water to the dried, packed soil to achieve the desired water by weight moisture.
  5. Place wandering SHB larvae produced according to standard rearing procedures (see section in the pupation containers once the soils are conditioned to need.