European swallowwort [Vincetoxicum rossicum (Kleopow) Barbarich] is found in the northeastern United States and southeastern Canada. It forms dense growth patterns that reduce plant and insect biodiversity, and lab assays show that it produces allelopathic compounds that affect microbial activity. Consequently, we hypothesized that V. rossicum alters soil microbiome composition and activity in invaded habitats, which may impact ecosystem properties and processes. We sampled soil from a similar time point within a growing season at each of five sites in New York State where V. rossicum was both present and absent. We measured bacterial and fungal microbiome composition, available soil nitrogen (N), soil respiration (CO2 flux), and soil extracellular enzyme activities. Microbial composition varied across field sites, but only fungal composition was affected by invasion. No significant differences were found between the invaded and uninvaded plots at any of the sites for available soil ammonium, nitrate, or respiration, though extractable N varied greatly between sites. Microbial hydrolytic extracellular enzyme activities suggest decreased protein degradation and increased oxidative enzyme activity with V. rossicum invasion, which is relevant to soil N and carbon cycling processes. Although V. rossicum impacted rhizosphere microbial composition and activity, it was not associated with large perturbations in ecosystem function when examined across multiple invasion sites during this short-term study.

Microbial isolates from the gut region of larvae and adults of the variegated grasshopper Zonocerus variegatus (Linnaeus) were screened for extracellular production of the enzymes lipase, amylase, esterase, protease, linamarase and cellulase. Using the pour-plate culture technique, 15 bacterial, 4 yeast and 5 mould isolates were tested. None of the bacterial isolates showed lipase activity, but virtually all showed esterase and protease activities. Many bacterial isolates demonstrated linamarase and cellulase activities, and a few of them amylase activity. Of the yeast isolates, a few had amylase activity. None of the mould isolates showed enzyme activity, except Aspergillus sp., which showed lipase activity. Evidently, the gut of Z. variegatus contains micro-organisms that are able to produce digestive enzymes. Of significance is the biosynthesis of linamarase (β-d-glucosidase) by the grasshopper's gut bacteria, which probably contributes to the insect's neutralization of the toxic effects of cyanogenic glycosides present in cassava (Manihot esculenta), one of its major food plants.