Synthesis and Evaluation of the Naturally Occurring Phototoxin Alpha-terthienyl as a Control Agent for Larvae ofAedes intrudens, Aedes atropalpus(Diptera: Culicidae) andSimulium verecundum(Diptera: Simuliidae)

Abstract

New methods to synthesize alpha-terthienyl ( α-T ) on a large scale have permitted field and laboratory evaluation of this naturally occurring phototoxin from plants for blackfly and mosquito control. The acute toxicity of α-T to blackfly larvae ( Simultum verecundum Stone and Jamnback) was LC50 = 28 ppb and LC90 = 70 ppb. In field trials effective control of third- and fourth-instar larvae of Aedes intrudens Dyar was achieved with application of 0.1 kg/ha to natural breeding pools. Similar results were found in simulated pool trials conducted under more controlled conditions with laboratory-reared Aedes atropalpus Coquillett larvae. Alpha-terthienyl is not persistent, with a half-life of -4 h in sunhght. The results suggest possible use of the phototoxin for mosquito control.