Survival time of unfed, first-instar western corn rootworm (Coleoptera: Chrysomelidae) and the effects of soil type, moisture, and compaction on their mobility in soil
1990
Macdonald, P.J. | Ellis, C.R.
If soil factors at the time of hatch significantly influence the survival time of newly eclosed rootworm larvae or their ability to move through the soil to host roots, monitoring significant factors may provide an opportunity to improve predictions of economic damage. Survival time of Diabrotica virgifera virgifera LeConte was reduced at less than 100% RH and as temperature increased. Larvae moved farthest in loam soil with 24 and 30% moisture (-0.38 and -0.13 bars). Movement was restricted in wet soil (36%, or -0.05 bar) and in soil with 18% moisture or less. Larvae moved more than three times farther through silty clay or loam than through loamy sand. Movement through loam soil at a matric potential -0.38 bar was unaffected by bulk densities of 1.2 to 1.8 g/cc, and at least 5% of larvae moved to the farthest section of the test chamber at all bulk densities within 6 h under these conditions. Larvae survived for sufficient time in the soil to reach roots under most soil conditions. When soil is very wet or dry, increased mortality or decreased movement can reduce larval establishment.
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