Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2003
Publication Date: 9/15/2003
Citation: XUE, R., BARNARD, D.R. BORIC ACID BAIT KILLS ADULT MOSQUITOES (DIPTERA: CULICIDAE). JOURNAL OF ECONOMIC ENTOMOLOGY. 2003. v.96(5).p.1559-1562. Interpretive Summary: Adult mosquito control is based primarily on the aerial application of insecticides. When applied improperly, however, insecticides can pollute the environment, kill beneficial insects, and lead to insecticide resistance in the mosquito population. ARS scientists at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL study new ways to control mosquitoes without using insecticides. One technique they have developed for this purpose is to combine a poison (boric acid) with a bait (sugar/water solution) and to make the mixture available as food for adult mosquitoes. Laboratory tests showed that a mixture of 1% boric acid in sugar water killed 98% of the test mosquitoes in 48 hours; furthermore, when given a choice between bait with, and without, boric acid, 73% of mosquitoes fed on the former and died within 48 hours. In outdoor tests, the use of boric acid baits reduced mosquito biting rates on a human subject by 78%. Scientists believe that boric acid baits can be used to reduce adult mosquito populations. If designed for economy and ease of use, boric acid bait stations could provide a safe, non-insecticidal, point-source control method for mosquitoes in urban and suburban environments and in some types of livestock housing.
Technical Abstract: The toxicity of boric acid solutions to adult Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, and Aedes albopictus Skuse was evaluated in the laboratory. Median lethal concentrations (LC50) at 24 h exposure for male and female An. quadrimaculatus were 0.317 and 0.885, respectively; for Cx. nigripalpus, 0.273 and 0.560, respectively; and for Ae. albopictus, 0.174 and 0.527, respectively. The LC50 values at 48 h exposure for male and female An. quadrimaculatus were 0.101 and 0.395, respectively; for Cx. nigripalpus, 0.098 and 0.255, respectively; and for Ae. albopictus, 0.078 and 0.244, respectively. In laboratory tests, access for 48 h to sucrose (10%) water containing 1% boric acid (boric acid bait) resulted in 98% mortality in blood fed, gravid, and parous Ae. albopictus. In choice tests in the laboratory between boric acid bait and sucrose water, 52% of male and 33% of female Ae. albopictus ingested sufficient boric acid bait in 24 h to cause mortality; after 48 h, respective percent mortalities were 88 and 58%. In outdoor tests, in a walk-in screened cage (156 m3) containing 1250 female Ae. albopictus, mosquito biting rates on the exposed forearm of a human subject in a 3 min exposure period were reduced 78% for the boric acid bait group compared with a sucrose water control.