If you’ve followed this blog, you may know I have a penchant for word play and grammar jokes. So yes, here’s another one:
Black and Bluhm – in reference to Agrotis ipsilon (black cutworm) migration patterns and Wilbur L. Bluhm, Emeritus OSU Extension agent who tracked the phenology of many ornamental plants for over 40 years. His dataset is specific to the mid-Willamette Valley.
Phenology is the study of periodic life cycle events and how they change from year to year. It is an armchair hobby of mine, and also has direct implications for crop pest monitoring. Plants and animals alike develop and progress through life cycle events (leaf out, molting, bud break, etc.) according to temperature.
When Spring arrives 20 days earlier than normal, the implications become even more important. In the animation below, red represents “spring leaf index” occurring earlier than normal and blue indicates later.
Black cutworm, like many crop pests, exhibits long-range migration behavior, and adult moths depend on nectar sources to literally fuel their journeys. A recent study1 examined pollen load on A. ipsilon antennae and found that they are especially frequent visitors to flowering woody dicots like honeysuckle, hawthorn, hazelnut, alder, oak, maple, etc.
According to Bluhm’s tracking2 , most of the plant species mentioned above are, in general, blooming earlier than they used to here in Oregon. This obviously varies widely by year and by species, but bear with me…
If more floral resources are available, earlier, and insect development also is ‘ahead of schedule’, it stands to reason that moth flights could be affected.
The chart below shows peak flowering of three common woody species, and their phenology over the past few decades. I compared this to my dataset of black cutworm moth trap counts and found an interesting pattern:
And now, just for fun..listen to this and ponder the potential relationship between black and bl[oom] !
1 Liu, Y., et al. 2016. Host Plants Identification for Adult Agrotis ipsilon, a Long-Distance Migratory Insect. Int’l. J. Mol. Sci.,17(6).
2 The Wilbur L. Bluhm Plant Phenology Study <http://agsci-labs.oregonstate.edu/plantphenology/>