Phototactic response of Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) to yellow-coloured surfaces, and an attempt at commercial suppression using yellow barriers and trap trees

Abstract

AbstractTrioza erytreae (Del Guercio), the vector of the serious citrus greening disease, was found to be highly attracted to yellow surfaces, particularly fluorescent yellow-green (about 530 nm). The phototactic response was used to develop a monitoring trap using 3M Saturn Yellow self-adhesive tape adhering to a glass or Perspex sheet. Transparent PVC foils smeared with a thin layer of clear polybutene were clipped in position over the Saturn Yellow surface and acted as the sticky catchment surface. A spectroradiometric comparison of new and weathered traps indicated only a 10% decrease in reflectance after one year. The traps were a sensitive indicator of psylla abundance. Valencia orchards in the Transvaal, South Africa, supported higher population levels than did navel orchards. A mass-trapping experiment was also done, and involved a cordon of yellow sticky polyethylene strips (Gundle Flexipipe smeared with polybutene) placed around an orchard. This perimeter barrier was combined with aldicarb-treated trap trees within the orchard in an attempt to reduce further the already low psylla numbers. Inside the experimental area there was no statistically significant drop in psylla numbers compared with the control trees outside. These poor economic results making use of the flight response of T. erytreae suggest that carefully integrated biological and chemical suppression of the psylla vector is at present the most practical entomological method for containing greening disease on mature trees.