The present invention concerns methods for controlling insect infestation via RNAi-mediated gene silencing, whereby the intact insect cell(s) are contacted with a double-stranded RNA from outside the insect cell(s) and whereby the double-stranded RNA is taken up by the intact insect cell(s). In one particular embodiment, the methods of the invention are used to alleviate plants from insect pests. Alternatively, the methods are used for treating and/or preventing insect infestation on a substrate or a subject in need of such treatment and/or prevention. Suitable insect target genes and fragments thereof, dsRNA constructs, recombinant constructs and compositions are disclosed.