Lack of relevant fitness costs in dsRNA-resistant Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) based on pre-imaginal biological parameters

The Colorado potato beetle, Leptinotarsa decemlineata Say (Col.: Chrysomelidae), is the most important solanaceous defoliator pest, causing >30% yield losses in potato crops around the world. This insect displays notorious ability to adapt to various biological and synthetic pesticides, although in some cases this adaptation carries relevant fitness costs. Insecticidal gene silencing by RNA interference (RNAi) activated by ingestion of double stranded RNA (dsRNA) is proposed as an effective tool for L. decemlineata control. We previously reported laboratory selection of a L. decemlineata population for >5,000-fold resistance to a topical dsRNA application. In this work, we tested the existence of fitness costs in this dsRNA-resistant colony when compared to the parental and an additional susceptible population. We determined and compared pre-imaginal biological parameters between the three beetle populations and our results show no significant differences between susceptible and dsRNA-resistant populations. This information is important to guide effective insect resistance maangement plans for topical dsRNA against L. decemlineata.