Using Plants to Kill Mosquitoes
Mosquitoes kill almost 1 million people each year when they transmit pathogens including Malaria, Dengue, Zika, and numerous others. Pesticides are the most common method used for controlling mosquito populations; however, pesticides are not specific and often have a negative impact on beneficial insect species and the environment. Our proposed solution is to use plants to deliver mosquito-specific toxins directly to mosquitoes. This work is sponsored by the Bayer Corporation and the B.F. Smith Foundation.
Controlled Delivery & Specificity
Male mosquitoes feed exclusively on nectar while female mosquitoes need nectar to fuel their blood quest flights. Leveraging this biology, the Kearney Lab is developing a system to deliver mosquito-specific peptide toxins produced in nectar for imbibition by mosquitoes. In this way, the mosquitoes travel to the nectar to receive a dose of toxin that kills only mosquitoes. In contrast, pesticides kill a wide array of insects and must be sprayed in sufficient volume to reach all mosquitoes, since pesticides kill by direct contact.
We have identified Impatiens walleriana as a plant which is highly attractive to mosquitoes and is easily transformed genetically (Chen and Kearney, 2015). Impatiens are the top selling flowering shade plant world-wide. We are developing this plant as a model system to study the delivery of anti-mosquito proteins through nectar to the mosquito. We have developed a mosquito-specific peptide and have an efficient impatiens transformation system in operation.
Tri-State Mosquito Feeding Behavior Study
A recent study by Kearney and Chen (2015) showed that Aedes and Culex mosquitoes will preferentially feed on the nectar of Impatiens walleriana. Since this study utilized large, indoor cages to test mosquito feeding behaviors, we were interested in seeing if impatiens will maintain this level of attractiveness in its normal outdoor environment: a garden. This means not only being outdoors, but also surrounded by potential competitors. This study will be conducted in Texas, Mississippi, and Florida to also measure whether regionality will influence mosquito attractiveness.
Isolating Native Promoters from Impatiens
In order to deliver toxins to mosquitoes, they must first be expressed in the nectar of impatiens. This requires a nectary promoter and nectar signal peptide. Finding a good candidate promoter requires a synthesis of protein, RNA, and DNA analysis. We have purified proteins from impatiens nectar and sequenced the most highly expressed protein with LC MS/MS mass spectrometry. We sequenced impatiens nectary, stem, and leaf RNA to find the most highly and preferentially expressed RNAs in the nectaries. These translated RNAs were compared to the mass spec generated amino acid sequences and the nectar protein was identified. The mRNA of this nectar protein was then used as a template to assemble the upstream promoter region using sequenced genomic DNA reads. We are currently working on transforming impatiens tissue culture with this promoter region to test its efficiency for foreign protein expression.
Pruett G., Hawes J, Varnado W, Deerman H., Goddard J., Burkett-Cadena N., Kearney C.M. 2020. The readily-transformable Impatiens walleriana efficiently attracts nectar feeding with Aedes and Culex mosquitoes in outdoor garden settings in Mississippi and Florida. Acta Tropica 210:105624. doi.org/10.1016/j.actatropica.2020.105624
Chen Z.Y.and Kearney C.M. 2015.Nectar protein content and attractiveness to Aedes aegypti and Culex pipiens in plants with nectar/insect associations. 2015.Acta Tropica 146:81–88.http://dx.doi.org/10.1016/j.actatropica.2015.03.010