Honeydew as Danegeld? Ants (Hymenoptera: Formicidae) Tending a Honeydew-producing Homopteran do not Offer Protection From its Main Natural Enemies

Ants often protect honeydew-producing homopteran bugs from their natural enemies. Although such ant-homopteran interactions are often found to be conditional on the ecological context under which the interactions take place, there is a prevalent assumption that rewards in the form of protection from natural enemies are the norm. Here we describe a homopteran-ant interaction where such rewards appear to be absent. The polyphagous honeydew-producing homopteran Hilda patruelis frequently feeds on the Cape fig (Ficus sur) and other African fictrees where it is almost invariably found in the presence of ants, usually Pheidol megacephala. Our ant exclusion experiments in South Africa failed to detect any change in H. patruelis numbers, and the ants provided no protection from its only local parasitoid or the majorlocal invertebrate predator. The parasitoid wasp appears to have specialised adaptations to avoid ant predation, while the predator (larvae of a lycaenid butterfly) is probably itself an ant mutualist. Although it cannot be confirmed that H. patruelis is not protected From natural enemies elsewhere across its range or at different times, it appears that the main benefit accruing to H. patruelis from honeydew production is chat the ants desist from attacking them. As such, Danegeld, the historical practice of paying extortion money to Vikings to buy off their attacks, may be a more accurate description of the relationship than mutualism. Ants attracted by H. patruelis can benefit their host fig trees, so an indirect multi-species mutualism is being generated in the absence of more direct mutualistic interactions.