Arthropod abundance censused on the host plant Ligusticum porteri near Gothic, CO

The objective of this study is to understand how climate cues affect the abundance and phenology of aphids and the arthropods with which they interact. These data were collected in 20 populations of the host plant (Ligusticum porteri) along an elevation gradient near Gothic, CO, USA. We randomly-selected ten host plants in each populations to serve as subjects of the monitoring. Using weekly censuses, we recorded flowering stalk abundance, flowering stalk phenology and arthropod abundance on flowering stalks over nine weeks in 2017 and ten weeks in 2018. We scored the flowering phenology of the terminal and primary umbels using an index published in Robinson et al. (2017). The primary herbivore observed in this system is the sunflower aphid, Aphis helianthi. These aphids are tended by several species of ants. Other arthropods common on inflorescences include adults and nymphs of the family Miridae, chiefly those belonging to the genus Lygus.