A novel trophobiotic interaction between a Neotropical stink bug and an ant species: Insights into potential benefits to the host plant

Trophobiotic interactions occur when phytophagous insects provide a sugary liquid, the honeydew, for ants and obtain defence against predators or parasitoids. The plants may indirectly benefit from an increased ant foraging activity by reducing the herbivorous abundance. These three trophic interactions have been previously studied for several species, but mainly involving plants with extrafloral nectaries, which is a plant structure that also produce attractive substances for ants. Previous studies have reported an ant preference for honeydew over extrafloral nectary content. Therefore, trophobiosis can be an important mediator of ant-plant interactions. In this study, we describe a trophobiotic interaction between Edessa contermina stink bugs and Camponotus blandus ants on the Byrsonima verbascifolia plants occurring in a conservation area of Brazilian savanna. Stink bugs excreted a sugary liquid which was consumed by the ants, and C. blandus ants were observed consuming potential parasitoids. Stink bugs were more abundant in plants containing high food supply and shelter availability. The occurrence of ants depended of the number of inflorescences and trunk circumference of B. verbascifolia. Ant abundance, however, was positively correlated with stink bug abundance and the number of inflorescences. Herbivory was not explained by neither plant architecture nor ant abundance. This high ant activity may benefit plants from a protection against herbivory, but we did not detect this effect during the study period. Hence, the interaction among ants and plants was apparently commensal. We concluded that plant traits were important in ant attraction, but stink bugs foraging also increased ant activity on the plant, but mainly on inflorescences. Therefore, the plant may benefit from an increased defence of inflorescences rather than leaves.