A biodegradable lethal ovitrap for control of container-breeding Aedes

Abstract

Lethal ovitraps (LO) have been successfully deployed in dengue control operations in north Queensland, Australia since 2004. However, the current plastic-bucket LO must be retrieved before the pesticide-treated strip degrades and the trap begins producing mosquitoes. The logistics involved with trap retrieval are considerable and include recording trap location and retrieval date onto a database, locating and retrieving each trap, and examining lethal ovitraps for eggs. Collectively, these necessary activities greatly reduce the efficiency of dengue control. In response, we have developed a biodegradable lethal ovitrap (BLO) that does not need to be retrieved for the control of container-breeding Aedes, particularly Aedes aegypti. The BLOs were made by injection molding with the use of 2 proprietary blends of thermoplastic starch (TPS) polymer based on plasticised amylose maize polymers. In field trials, Ae. aegypti readily oviposited in BLOs, with those dyed black with the use of carbon black preferred. Water loss was higher in BLOs than in standard plastic LO because of weeping from the walls, although none of the BLOs failed in the 5 wk of the trial. The occurrence and rate of Ae. aegypti oviposition in both BLOs and the LO was comparable. In an accelerated standard composting trial (ISO16929:2002E), both BLOs fragmented within 4 wk, and no BLO particles were visible after 12 wk. Large numbers of BLOs could be deployed in a “set it—and forget it” strategy to control Ae. aegypti and to stop dengue transmission, and could be used in a community participation program to maximize coverage.