By Blake Jackson
During the summer of 2023, a curious outbreak of enlarged flower buds, resembling galls, swept across American elderberry plants in Missouri. These galls, caused by unknown insect larvae, prevented fruit development and resulted in yield losses.
Researchers initially suspected the culprit to be the gall midge Placochela nigripes, based on visual similarities with its European counterpart. However, closer examination under a microscope revealed distinct differences in larval morphology, casting doubt on this identification.
Raymond Gagne, a Smithsonian expert, provided a potential key: Schizomyia umbellicola, another gall midge species. This identification stemmed from analyzing photographs of the larvae. However, definitive confirmation requires adult specimens, which remain elusive.
The investigation took another turn with the discovery of similar galls on blue elderberry, harboring pale green larvae with distinct markings. This was identified as a separate, undescribed lepidopteran species, highlighting the diverse gall-inducing fauna targeting elderberry plants.
The quest to identify the true culprit continues. Future efforts will focus on:
- Rearing adults: Obtaining adult specimens will enable morphological analysis and solidify species identification.
- DNA analysis: Comparing DNA of the Missouri larvae with known species will provide conclusive evidence.
- Field trials: Investigating potential control measures targeting adult midges before they lay eggs in elderberry florets.
This case illustrates the intricate world of gall-inducing insects and the challenges associated with their identification. By unraveling the mystery behind the Missouri elderberry galls, researchers can develop effective management strategies to protect these valuable plants and their fruit yield.
Photo Credit: university-of-missouri
Categories: Missouri, General