The Colorado potato beetle (CPB; Leptinotarsa decemlineata) is one of the most notorious and difficult to control
pests of potato and other solanaceous crops in North
America. This insect has evolved a remarkable ability to
detoxify both plant and synthetic toxins, allowing it to
feed on solanaceous plants containing toxic alkaloids and
to develop resistance to synthetic chemicals used for its
control. RNA interference (RNAi) is a natural mechanism
that evolved as an immune response to double‐stranded
RNA (dsRNA) viruses where dsRNA triggers silencing of
target gene expression. RNAi is being developed as a
method to control CPB. Here, we evaluated four CPB‐
specific genes to identify targets for RNAi‐mediated
control of this insect. Out of the four dsRNAs evaluated
in CPB larvae and adults, dsIAP (dsRNA targeting inhibitor of apoptosis, iap gene) performed better than
dsActin, dsHSP70, and dsDynamin in inducing larval
mortality. However, in adults, the mortality induced by
dsActin is significantly higher than the mortality induced
by dsIAP, dsHSP70, and dsDynamin. Interestingly, a
combination of dsIAP and dsActin performed better than
either dsIAP or dsActin alone by inducing feeding inhibition in 24 hr and mortality in 48 hr in larvae. When
the dsIAP and dsActin were expressed in the Escherichia
coli HT115 strain and applied as a heat‐killed bacterial
spray on potato plants, it protected the plants from CPB
damage. These studies show that the combination of
dsIAP and dsActin shows promise as an insecticide to
control CPB