Nectar robbing does not affect female reproductive success of an endangered <i>Antirrhinum</i> species, Plantaginaceae

<b>Background:</b> Nectar robbers in many plant species affect female reproductive success, usually decreasing the amount of seed produced by plants, which can affect populations persistence. <b>Aims:</b> To evaluate the impact of nectar robbers on the viability of the populations, we investigated the effects of nectar robbing on the female reproductive success of a threatened snapdragon species in four populations over 2 years. <b>Methods:</b> We observed insect visitors and their behaviour and quantified the percentage of robbed and non-robbed flowers and the production of fruits and seeds. <b>Results:</b> The results showed the degree of variation in nectar robbing among the populations and between years within the populations. Nectar robbers were detected in only two populations, and all were <i>Bombus terrestris</i>. Differences in flower size among populations were not related to the nectar robbing behaviour of <i>B. terrestris</i>. A comparison of the percentage of fructification and seed production between flowers that were and were not robbed showed no evidence of a negative effect of nectar robbing. <b>Conclusions:</b> Our study reports for the first time on nectar robbing in <i>Antirrhinum</i> species and concludes that this does not affect the female reproductive success of individuals or the viability of <i>A. valentinum</i> populations.