Quantification of movement and spatiotemporal distribution of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) in a citrus orchard using a protein marking technique

Effect of plant water stress on Homalodisca vitripennis dispersal and movement was evaluated in citrus orchards during a two-year study. Irrigation treatments included watering at 100%, 80%, and 60% of the crop evapotranspiration (ETc). Movement of H. vitripennis among treatment plots was quantified through a mark and capture technique using protein markers (soy milk, whole milk, and egg white) and yellow sticky traps. In 2006, 75, 78 and 63% of H. vitripennis captured in the 60, 80, and 100% ETc treatments, respectively, were insects that immigrated from the other two irrigation treatment plots. Movement of H. vitripennis from its preferred habitat (80% ETc treatment plots) towards unsuitable host plants (trees irrigated at 60% ETc), combined with estimates of population densities observed in visual and beat sampling, suggest that in mature orchards H. vitripennis is unable to use visual or olfactory cues to search for a suitable host plant and thus, plant selection is determined after contact with the plant by chemosensory or mechanosensory stimulus after probing.