Six-year Evaluation of Brown Citrus and Spirea Aphid Populations in a Citrus Grove and the Effects of Insecticides on these Populations

Abstract

The population densities of the brown citrus aphid (BrCA) (Toxoptera citricidus Kirkaldy) and the spirea aphid (SA) Aphis spiraecola Patch were monitored by scouting weekly for 6 years in a replicated citrus plot treated with 7 insect control regimes: Admire (imidacloprid) applied at 12, 6, 3, or 2 month intervals; Temik applied annually; Meta-Systox-R applied annually; or no insect control. The numbers of both aphid species varied greatly from month to month and year to year. The brown citrus aphid was normally only detected in the fall (August through December) with populations peaking in September, October, or December depending on the year. The spirea aphid could be detected throughout the year during years when overall populations were high. Spirea aphid populations often peaked both in the spring and fall. Annual applications of Temik or Metasystox were ineffective in reducing aphid populations. Generally, all four Admire treatment regimes controlled aphids, although at least 2 annual Admire treatments per year were required to control the spirea aphid during some years.