Seasonal Biology of the Invasive Green Stinkworm Amynthas hupeiensis and Control of Its Casts on Golf Putting Greens

Abstract

Amynthas hupeiensis (Michaelsen) is an invasive east Asian megascolecid earthworm whose prolific casting disrupted maintenance and playability of golf courses along the United States Atlantic seaboard during the 1940s and 1950s. The worm was recently found damaging sand-based greens of central Kentucky golf courses. This is the first report of A. hupeiensis infestation of golf courses west of the Appalachian Mountains and the first from golf courses anywhere in the United States in more than 60 years. We document A. hupeiensis seasonal biology and casting and evaluate chemical and organic vermicides for mitigating its damage on sand-based putting greens. Unlike ubiquitous European-origin earthworms that are active in golf course turf on native soil in early spring and late autumn, A. hupeiensis produces large, sinuate casts on sand-based greens, especially from May to September. Casting occurs day and night so that greens mowed in the morning are covered with new casts by afternoon. All life stages were present in greens from April to October. A single spring application of the neonicotinoid-pyrethroid combination insecticides clothianidin + bifenthrin (Aloft) or zeta-cypermethrin + bifenthrin + imidacloprid (Triple Crown) reduced casting by more than 95% for the rest of the growing season. Products with tea-seed saponins, concentrated pyrethrins, or soluble sulfur did not suppress casting by A. hupeiensis. We hypothesize that A. hupeiensis may be introduced onto golf courses as cocoons in compost, soil, or crude river sand used for course renovations, a scenario supported by events at our most egregiously infested study site and by confirmation of presence of A. hupeiensis along sandy riverbanks in Kentucky.

Ecology and management of earthworm casting on sports turf

“…Certain megascolecid (Appendix S1) species (e.g. Amynthas hupeiensis , endogeic), however, can be abundant in sandy soils such as sand‐based putting greens and tees . Earthworms are also rarely found in high‐clay soils where oxygen gas concentrations can become deficient and air diffusion through the earthworm's external mucous layer is inhibited; however, the effect of soil texture on earthworm activity in turfgrass systems is not always consistent.…”

“…Earthworm life cycles vary by species and determine which life stages are present at different times throughout the year. For example, Amynthas hupeiensis , a problematic endogeic species on eastern United States' golf courses, has peak adult populations in spring and autumn, whereas juveniles are most common throughout the summer . For that species, peak casting activity occurs in late spring through early autumn, with no casting activity throughout the winter .…”

“…For example, Amynthas hupeiensis , a problematic endogeic species on eastern United States' golf courses, has peak adult populations in spring and autumn, whereas juveniles are most common throughout the summer . For that species, peak casting activity occurs in late spring through early autumn, with no casting activity throughout the winter . Little is known about the overwintering life stage or processes of Amynthas hupeiensis in low‐cut turf in the USA.…”

“…a), water retention in the canopy layer, weed and disease invasion, reduced aesthetics, reduced photosynthesis, and can interfere with ball roll and playability . Earthworm casts dull mower blades and accumulate between mowing units, preventing a clean cut and requiring frequent stops to remove casts from the mower . Cast properties are greatly influenced by soil type as well as earthworm species, but typically occur in four forms: mounds of spherical granular pellets of various sizes (Fig.…”

“…One species, Amynthas hupeiensis produces large, sandy, often sinuous, casts (Fig. e) on sand‐based greens . Regardless of shape, wet, muddy casts are more difficult to manage than dry, sandy casts, which can be more easily incorporated into the turfgrass canopy.…”