Introduction, control, and spread of Aedes albopictus on Grand Cayman Island, 1997-2001

Infestations of Aedes albopictus were first identified in the Cayman Islands on June 19, 1997. Control techniques that had previously been effective in the elimination of Ae. aegypti from these islands were employed with the aim of eliminating this species. Chemical control methods against adult mosquitoes used a combination of ultra-low-volume applications of fenthion, backpack spraying with permethrin, and residual wall treatments with lambda-cyhalothrin. Larval stages were also targeted with the use of granular formulations of temephos and methoprene applied to all containers capable of sustaining larval development. For a 2-year period after the discovery of the introduction the abundance of this mosquito remained low (Breteau index = 0.6); however, in 1999 Ae. albopictus became firmly established (Breteau index = 5.5). By the end of 2001 it was apparent that the control methods utilized had failed to stop the spread of this species. This work describes the control methods utilized and discusses possible reasons for the failure of the elimination campaign.