Plant extract effect on mosquito survivorship: determining the efficacy of ailanthone to control adult mosquitoes

Due to the negative environmental impact and resistance to chemical control agents, the development of biological control or biocides has increased significantly over the past half century, the potential of plant extracts as potential control agents has only recently begun to attract attention. Tree of Heaven (Ailanthus altissima) is a non-native tree from Asia and produces the allelopathic compound, Ailanthone. This compound is known to have herbicidal and there is anecdotal evidence that it possesses insecticidal qualities. The purpose of this study was to examine the potential of A. altissima extract as a botanical insecticide on adult mosquitoes.

 Two extraction methods (leachate and maceration) were utilized on newly emerged, mature, and senesced leaves to influence extracted potency on adult mosquito survivorship. Three genera of mosquitoes (Aedes japonicus, Anopheles quadrimaculatus, and Culex quinquefaciatus) and one non-target species (painted lady butterflies; Vanessa cardui) were treated with serial dilutions of ailanthone via two methods: 1) through spray contact exposure and 2) through sugar meal feeding. Adult mosquitoes (n=25 per cage; 3 cages per treatment) were exposed to 100,75,50,25% dilutions of A. altissima extract either from leachate or macerated leaf extraction. Mosquitoes were monitored for 24 hours to quantify survivorship. Adult mosquito mortality varied significantly among dilution factors and leaf age. These findings indicate that an invasive plant extract that the plant uses both as an herbicidal weapon against plant competitors and an insecticidal tool to deter insect herbivores may have potential as a biological control strategy for several major mosquito vectors of human disease pathogens.