Effect of Soil Moisture and Time of Year on Mole Cricket (Orthoptera: Gryllotalpidae) Surface Tunneling

Abstract

The damage caused by two species of introduced mole cricket pests (Scapteriscus vicinus Scudder and Scapteriscus borellii Giglio-Tos) was studied during 1995, 1996, and 1997 in Brunswick County, NC. Surface tunneling activity in bermudagrass was quantified weekly starting in late July or early August using a modification of the damage grid evaluation method of Cobb and Mack (1989). Soil moisture was monitored in three depth ranges (0–10.2, 10.2–20.3, and 20.3–30.5 cm) and percentage soil moisture based on dry soil weight was determined gravimetrically. Most sites had a higher percentage of S. borellii than S. vicinus, with the percentage of S. borellii ranging from 42–95%. The percentage soil moisture ranged from 1.2–24.9, 1.3–19.3, and 1.3–20.4% at 0–10.2, 10.2–20.3, and 20.3–30.5-cm, respectively. Moisture percentages in the 10.2–20.3- and 20.3–30.5-cm ranges were not significantly different. Mean percentage soil moisture in the 0–10.2 cm range was significantly greater than for the 10.2–20.3 and 20.3–30.5-cm ranges combined. Average damage ratings (0–9) increased linearly with Julian date, but due to differences in damage levels among the years, three separate linear equations were used to describe the relationship. Mean damage ratings increased by one rating point (11%) every 2–3 wk. A significant nonlinear relationship was found between percentage soil moisture and mean damage ratings. Management implications of the findings are discussed.