1991/04/01 by James L. Krysan, David R. Horton, David Horton · 1 citation
Agricultural and Biological Sciences · Environmental Science · #Insect-Plant Interactions and Control #Phytoplasmas and Hemiptera pathogens #Forest Insect Ecology and Management
paper · doi:10.1093/ee/20.2.626
Sampling of summer form and winter form pear psylla, Cacopsylla pyricola (Foerster), was undertaken during four years and in two orchards using three methods: yellow sticky traps, clear sticky traps, and beating tray (limb jar techniques). Catches on yellow and clear sticky traps were positively correlated; correlations between trap catches and beating tray numbers tended to be nonsignificant. Catch of summer forms and fall populations of winter forms was much greater on yellow traps than on clear traps. In early spring (before bud break) clear traps captured as many or more psylla than yellow traps; but yellow traps caught far more psylla as green tissue appeared on pear trees. Differences in numbers caught on the two colors were larger for traps hung at the higher of two heights; however, in percentage terms (percentage of total captures occurring on yellow), no position effects were noted. Catches of spring populations of winter forms on sticky traps were highly biased toward male psylla. Similar trends in sex ratio bias were noted for the earliest spring beating tray samples; male bias decreased on successive sampling dates.