First record of field dodder (Cuscuta campestris) parasitizing invasive buffalobur (Solanum rostratum)

Abstract

Solanum rostratum (buffalobur) is one of the infamous invasive cosmopolitan weeds. Until now, however, there is no efficient method to control this weed. To find potential biological control agents for it, we carried out field surveys in Northeast China, and tested effects of a potential agent on buffalobur and their structural connection in both fields and chambers. A dodder was observed on buffalobur in two adjacent poplar woodlands along Daling River, Liaoning Province in 2016 and 2018, respectively. The orange leafless twining dodder stems tightly entwined the stems and petioles of buffalobur, spread aggressively among buffalobur individuals, greatly inhibiting growth and reproduction of this weed. The dodder could also inhibit growth of this weed in chambers. Structural connection between the dodder and the buffalobur seedlings grown in a chamber was observed clearly using a paraffin sectioning, providing direct evidence for the parasitic relationship. The dodder was identified as holoparasite Cuscuta campestris (field dodder) based on its floral morphology and sequences of the second internal transcribed spacer (ITS2) of nuclear ribosomal DNA. To the best of our knowlege, this is the first record of field dodder parasitizing the invasive buffalobur in the world.