PROLONGED EXCLUSION OF FORAGING ANTS (HYMENOPTERA, FORMICIDAE) FROM CITRUS TREES USING CONTROLLED-RELEASE CHLORPYRIFOS TRUNK BANDS

Controlled-release chlorpyrifos trunk bands excluded foraging ants (Ir idomyrmex spp.) from citrus tree canopies for four growing seasons (18 2 and 211 weeks in two separate trials). The level of exclusion averag ed 92.7% over the full period of the trials. Laboratory bioassays of w eathered band material showed the bands were still toxic to ants (98-1 00% mortality) after 200 and 229 weeks. In contrast, trunk application s of gamma-cyhalothrin and a chlorpyrifos 'emulsion' were very short-l ived (<14 weeks) in their activity against foraging ants; levels of ex clusion over 15 to 18 weeks averaged 46% for lambda-cyhalothrin and 23 % for the chlorpyrifos 'emulsion'. The potential of controlled-release chlorpyrifos trunk bands as a practical management strategy for forag ing ants in citrus groves is discussed.