Jillian Dunbar, a student at the University of Alabama, worked with Ellen Martinson and Vincent Martinson in the lab of Dr. Michael Strand.
Reproduction and immunity are metabolically expensive systems; therefore, organisms with a limited amount of resources have to invest carefully (Schwenke et al. 2016). With the goal of producing offspring, organisms must invest resources into reproduction, yet also reserve resources for protecting themselves. In many cases reproduction and immunity are not directly linked. However, it has been shown in Aedes aegypti mosquitoes that, in addition to inducing egg production, a blood meal also increases the number of circulating immune cells called hemocytes (Castillo et all. 2011; Castillo et al. 2006). These findings elicit the question, does reproduction (blood-feeding) result in lower immunity for the mosquito? Through a variety of bacterial injections into blood-fed and non-blood-fed mosquitoes, this project worked to understand the possible tradeoffs between immunity and reproduction. We found an inverse relationship between immunity and reproduction, in that mosquitoes laid fewer and smaller eggs when injected with both live and heat-killed bacteria, but only for the more virulent species and higher doses. Interestingly, the results also showed that blood-fed mosquitoes were more successful in clearing or tolerating less virulent bacterial infections, suggesting resources gained from a blood meal are used to produce an anticipatory immune response. These preliminary findings are essential for continuing research and strengthening our understanding of the A. aegypti immune system with hopes of controlling or preventing diseases propagated by A. aegypti in the future.
References
Castillo, J, Brown, MR and Strand, MR (2011) Blood feeding and insulin-like peptide 3 stimulate proliferation of hemocytes in the mosquito Aedes aegypti. PLoS pathogens 7: e1002274.
Castillo, J, Robertson, A and Strand, M (2006) Characterization of hemocytes from the mosquitoes Anopheles gambiae and Aedes aegypti. Insect biochemistry and molecular biology 36: 891-903.
Schwenke, RA, Lazzaro, BP and Wolfner, MF (2016) Reproduction–immunity trade-offs in insects. Annual Review of Entomology 61: 239-256.
Dunbar