P. T. Hertl

Effect of Soil Moisture on Ovipositional Behavior in the Southern Mole Cricket (Orthoptera: Gryllotalpidae)

Abstract The relationship between soil moisture and oviposition in an edaphic insect pest, the southern mole cricket, Scapteriscus borellii Giglio-Tos, was studied in a series of greenhouse experiments. Adults were captured in acoustic calling traps and associated pitfall traps during spring flights in southeastern North Carolina in 1996, 1997, and 1998. Female mole crickets were individually confined in chambers containing 2, 4, 7, 10, and 12% soil moisture. Oviposition and mortality were monitored daily. A significant linear relationship between oviposition and soil moisture was indicated by an increase in the number of crickets ovipositing in response to higher soil moisture levels. Additionally, a delay in oviposition was observed as a response to low soil moisture. There were no significant differences in the number of eggs per ovipositing female, indicating that when oviposition does take place, the individual response of the female is to lay a similar number of eggs regardless of moisture levels. The ovipositional response to a rapid increase in soil moisture was also examined. The rapid increase in moisture resulted in a significantly greater percentage of females ovipositing, as seen in the previous experiments.

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.

First Record of Larra bicolor (Hymenoptera: Crabronidae) in North Carolina

ABSTRACT Here we report on the first record of the mole cricket parasitoid Larra bicolor F. (Hymenoptera: Crabronidae) in North Carolina. The presence of larvae and adults was documented at a mole-cricket-infested golf course near the South Carolina border. The means of arrival is not known, and may have occurred at the same time the hosts arrived or as the result of natural dispersal and range expansion. Evidence suggests that the parasitoids were able to survive through at least one severe winter.