Expanding the niche of a specialized granivore: Populations of the red-shouldered soapberry bug (Jadera haematoloma) pollinate the seeds they consume

The relationship between host plants and their insect pollinator-seed-predators is one of the more specialized examples of insect-plant mutualisms. These relationships can be obligate and involve coevolution between plants and insects, such as is observed in the yucca moth-Yucca and fig wasp-Ficus systems. These relationships may also be facultative, involving more diffuse selection and coevolution between partners. We lack detailed understanding of the evolutionary consequences of facultative pollinator-seed-predation mutualisms on plant-insect interactions. In this study, beginning with field observations and detailed natural history, and followed by field and greenhouse experiments, we reclassify the red-shouldered bug Jadera haematoloma as a facultative pollinator-seed-predator. As a highly specialized seed-predator of plants in the Soapberry family, these insects use their elongated mouthparts to penetrate host seedpods and consume the seeds. Our study demonstrates that Jadera also use these beaks to access nectar as an alternative food source. In doing so, they act as an important pollinator, creating the very seeds that will feed the next generation of offspring. When nectaring, these insects carry pollen on the proboscis between flowers and between plants. Furthermore, our experiments reveal that the insect’s presence increases the seed set of its host plants. Scientifically, Jadera has played a critical role in the study of rapid-ecological adaptation. This expanded understanding of this insect’s feeding niche from specialist seed-predator to include generalized nectarivory could have far-reaching implications for its interpretation as a textbook example of rapid adaptation.