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Resumo
The bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), exclusively feeds on blood to grow, molt and reproduce. The occurrence of bed bugs in areas inhabited by humans has increased in recent years due to the evolution of insecticide resistance in bed bugs and increase in people travelling across countries. Current management strategies which include insecticide application, cold and heat treatments are not very effective in controlling bed bugs. Alternatively, RNA interference (RNAi) may act as a promising tool to control this insect.
In the current study, I investigated feasibility of RNAi tool for bed bug control. Housekeeping and developmental genes were screened to identify potential RNAi targets for bed bug population suppression. Housekeeping genes evaluated were vacuolar ATP synthase (vATPase) subunits A and E, and the muscle actin gene. For developmental genes, we tested the chromatin remodeling genes ATP dependent helicase brahma (brahma), Imitation SWI ( iswi), Chromodomain-helicase-DNA-binding Protein (chd-1), and DNA helicase INO80 (ino80). The dsRNA was prepared in vitro and injected into bed bugs with a nanoinjector. After injection, bed bugs were kept in growth chamber for 8 to 12 hours to recover, and then provided with blood meal. Only those bed bugs that fed to repletion were used in the experiment. In addition to injection, muscle actin dsRNA mixed in acetone was topically treated to nymphs. Knockdown of muscle actin, vATPase subunit E and brahma produced lethal phenotype after 20 days, while the other chromatin remodeling genes reduced fecundity. Gene knockdown after injection was confirmed by real-time quantitative PCR and was observed as early as two days and persisted for at least 30 days. Topically applied dsRNA had no effect in gene expression and survival. In conclusion, the results obtained in this dissertation contributes towards a better understanding of using RNAi-based insecticides for bed bug control.
