Wireworms (the larval stage of click beetles):

• reside in the upper layers of agricultural soil
• feed on the roots and germinating seeds of cereal crops
• are highly susceptible to desiccation (drying out)
• are sensitive to extreme soil temperatures and soil compaction.

Give two abiotic factors and two biotic factors that could affect the size of a wireworm population in a field.

Students investigated the population density of wireworms in the soil of two different agricultural fields:

• Site X: a conventional deep-tilled crop field
• Site Y: a conservation-tillage (no-till) crop field

A dilute non-toxic irritant, Solution Z (mustard seed suspension), can be poured onto the soil. This solution causes the wireworms to rapidly migrate to the surface of the soil within a few minutes but does not harm them.

Plan an investigation using Solution Z to compare the mean number of wireworms per $m^2$ in Site X and Site Y.