This paper describes the interactions between native birds, a specialist moth, and the moth’s new host in North America, Amur honeysuckle, a problematic non-native shrub.
On a bird survey in late fall 2015, I came across a small flock of chickadees that appeared to be finding food on the leaves of Amur honeysuckle along the Rouge River. This non-native shrub dominates the forest understory in this area, as it does over a large swath of North America east of the Great Plains. The feeding behavior was very interesting to me, as Amur honeysuckle is known to be largely free of insect herbivores, even more so than the other species of non-native honeysuckles that are so common in urban forests.
A closer look revealed that nearly every Amur honeysuckle had leaves that were heavily infested with leaf mines, and that the chickadees were opening these mines and feeding on the insects within them. This was even more intriguing! Because they live and feed within plant tissues, leaf mining insects tend to be very host-specific, and specialized insects like this were supposed to be especially rare on most introduced plants, Amur honeysuckle included.
I reared the tiny caterpillars, overwintered them, and had the emerging insects (which were moths) identified by DNA barcoding in 2016. I continued my observations on bird use of the moth larvae, the extent of the infestation, and population status in 2016. My paper details these findings, which are novel in several ways:
- This is the first record of this moth species, or any in the same moth family of over 2000 species, using Amur honeysuckle as a host in North America
- The native ranges of the moth and the shrub do not overlap, indicating evolutionary adaptation was involved in the host switch
- Some of the bird species using the moth larvae have never been documented feeding on leaf mining moths
- Because Amur honeysuckles holds leaves (with occupied mines) until well after killing frost, these larvae supply protein to birds at a time when other insects have become scarce
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