Can honey bees be used to detect rare plants? Taking an eDNA approach to find the last plants in a weed eradication program

Abstract

AbstractThe detection of rare taxa, crucial to conservation and biosecurity, presents many challenges that emerging technologies have the potential to address or avoid. Analysis of environmental DNA (eDNA) is a promising tool for the detection of rare species, especially when applied in a way that exploits natural processes to accumulate biological material (natural aggregation). This study investigated the potential of using honey bees as aggregators of pollen eDNA to detect Chrysanthemoides monilifera subsp. monilifera (boneseed), an introduced species targeted for eradication in Western Australia. We developed a species‐specific polymerase chain reaction (PCR)‐based assay that detected boneseed pollen at levels as low as 70 grains per million in a constructed pollen mixture. The assay was successfully used on wild‐caught bees from large boneseed populations, confirming they collect boneseed pollen. However, our results did not detect boneseed DNA in honey bee pollen collected from hive pollen traps near isolated boneseed plants. We hypothesize that a combination of low abundance of boneseed individuals, vast alternative flower resources at the time of boneseed flowering, and honey bee behavior and ecology may have led to lack of detection. We propose ways in which future work using honey bees to detect rare species can be improved. We also outline how other eDNA substrates (e.g., air and water samples) could be used with the PCR assay we have developed. More broadly, our work highlights the potential of eDNA techniques to detect rare species in biosecurity and conservation contexts and contributes to the development of pollinator‐based detection.