Host plant dispersion, leaf hopper movement and disease transmission

Abstract.

• 1 The plant-to-plant movement of the corn leafhopper, Dalbulus maidis Delong & Wolcott, and the spread of the leafhopper-borne maize rayado fino virus were investigated in four patterns of maize (Zea mays) dispersion.
• 2 D. maidis was less abundant and the spread of the virus was slower in dense stands of maize than in sparse stands.
• 3 When plant density was held constant, leafhoppers were more abundant in maize stands with relatively equidistant plant spacing (uniform dispersion) than in stands with densely-sown rows (linear dispersion) or double-sown hills (clumped dispersion), but there was no difference in virus incidence among these plant dispersion patterns.
• 4 Leafhoppers were less likely to move to adjacent plants in uniform plant dispersion patterns than in either linear or clumped dispersion patterns. This result may explain the lack of higher virus incidence in uniform stands, despite higher leafhopper abundance.
• 5 Leafhopper movement was consistent with a simple rule: the shorter the distance to the next adjacent plant, the more likely a leafhopper is to move between plants.
• 6 These results demonstrate that host plant dispersion can affect the abundance and behaviour of highly mobile herbivorous insects even when plant density is constant.