Original content is great, but sometimes it is unnecessary to reinvent the wheel, or in this case, the YouTube video about armyworm damage in wheat.
We are starting to monitor true armyworm (Mythimna unipuncta) in the PNW, but efforts from Midwest states are much more deliberate because the species can be so damaging to large acreage of grasses and grains.
Today I found this excellent video from Chris DiFonzo at Michigan State University. Chris explains damage to flag leaves, thresholds and how to scout for larvae, and predicted impact on yield. Grab a cup of coffee and watch the 8-minute video here: https://youtu.be/C-Pk0ANkDr4
A few months ago, a paper was published, confirming that Bogong moths (Agrotis infusa) use geomagnetic fields as a navigational tool for their en-masse aestivation flight.
Say what, now?
Long-range migrations are common in the insect world, the most ‘notable’ (as in..the one in which most people take an interest) is that of the monarch butterfly. The migrations occur each year, are purposeful, and serve some ecological function; to reach breeding sites, etc..
In the case of the Bogong moth, millions of moths leave the plains of Australia and fly towards the high country of the Victorian alps to escape the heat and avoid desiccation. They congregate in such large numbers in the mountainous habitat that indigenous peoples would go there to collect the moths as a food source. They are also a preferred staple for mountain pygmy possums. In autumn, the moths return to the plains to lay eggs and the cycle begins again.
Aestivation is just a fancy word for: reduced state of biological activity that occurs in response to hot and dry conditions. It is a sort of ‘summer hibernation’, if you will.
Closer to home, we have Euxoa auxiliaris that exhibits the same pattern (replace pygmy possums with grizzly bears and Australian Alps with Rocky Mountains). The study found that successful orientation relies on a combination of visual cues and magnetic frequencies emitted by the earth, and that when either cue was missing or altered, their flights became uncoordinated and erratic.
So yes, insects have joined the ranks of migratory songbirds, salmon, sea turtles, and probably many other organisms that use geomagnetic signals to navigate.
Now we just someone to develop the superhero series for these Persistent, Amazing, Perceptive, and Strong …mutants?
No, wait – that name’s already taken:
Author note: not sure why the Dreyer et al. is being referred to as the ‘first’ discovery – 1. Baker, R.R. and J.G. Mather, Magnetic compass sense in the large yellow underwing moth, Noctua pronuba L. Animal Behaviour, 1982. 30(2): p. 543-548.
Other note: concerns of pesticide distribution, bioaccumulation and toxicity levels in this type of system have been raised since at least 2006, and warrant further review, IMO
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 in western Oregon for over 40 years.
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:
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/>