Franco et al. (2015) have a manuscript that has recently been accepted to Insect Biochemistry and Molecular Biology in which they use RNAi to probe the function of the odorant receptor co-receptor (Orco) in Rhodnius prolixus.
The biological findings of the paper are interesting and seem to show that reducing Orco expression in R. prolixus resulted in a loss of the ability to efficiently find hosts, decreased feeding as measured in blood volume, slower development, reduced fecundity and increased mortality.
Some of the technical observations made by Franco et al. could be equally interesting to those keeping abreast of insect genetic technology developments.
Franco et al. approached the problem of modulating Orco expression as they only could, direct injection of double stranded RNA into the hemocoel of appropriately staged animals.
In their case they used a dsRNA some 500 bp long and injected 1 microgram in 2 microliters of water into the thorax of 5th instar nymphs.
They reported a 73% reduction in Orco expression in the antennae of males and females.
Notably they saw prolonged silencing under these conditions. Franco et al. report reduced Orco expression 120 days after their initial injection.
As the authors discuss, Rhodius prolixus seems highly amenable to dsRNA-mediated gene silencing and the kinetics of silencing suggests some interesting biology associated with the gene silencing system in this insect.
Franco, T.A., Oliveira, D.S., Moreira, M.F., Leal, W.S., Melo, A.C.A., Silencing the odorant receptor co-receptor RproOrco affects the physiology and behavior of the Chagasdisease vector Rhodnius prolixus, Insect Biochemistry and Molecular Biology (2015), doi:10.1016/j.ibmb.2015.02.012.