Flowers to selectively enhance the fitness of a host-feeding parasitoid: Adult feeding by Tuta absoluta and its parasitoid Necremnus artynes

•Effect of nectar and host-feeding (HF) on T. absoluta and N. artynes is studied.•Floral nectar enhanced lifetime fecundity in T. absoluta and N. artynes longevity.•Only HF increased fecundity in N. artynes.•Flowers had different effects on lifetable parameters of both pest and parasitoid. Several parasitoids require both host and non-host resources, such as nectar, for maintenance, survival and egg maturation. However, the impact of sugar feeding has primarily been studied in parasitoid species that do not engage in host-feeding, and the importance of non-host resources for host-feeding parasitoids has so far received little attention. The Palaearctic parasitoid Necremnus artynes has been shown to attack the exotic invasive Tuta absoluta in the field, but its parasitism is generally low. Understanding the use of host and non-host resources by this parasitoid could reveal whether there is potential for enhancing the biocontrol of T. absoluta through provision of targeted food supplements. Cage experiments were conducted to investigate the influence of selected non-host resources on the longevity and fecundity of both the pest and its parasitoid. The parasitoid was also provided with the opportunity to feed on larvae of the pest. Sweet Alyssum, Lobularia maritima, had the most pronounced effect on the fecundity and longevity of T. absoluta, while buckwheat Fagopyrum esculentum had the strongest effect on parasitoid longevity. Fecundity of T. absoluta was shown to be a function of the age of the adults and food sources provided. Sugar resources did not influence the egg load of N. artynes, whilst host-feeding was relatively ineffective at enhancing parasitoid longevity. Host-feeding had a strong positive effect on egg load. The impact of non-host resources on host-parasitoid interactions and the potential for using selective food resources in conservation biological control of the exotic pest T. absoluta are explored.