ACTION THRESHOLDS FOR STRIPED CUCUMBER BEETLE (COLEOPTERA, CHRYSOMELIDAE) ON CAROLINA CUCUMBER

Field studies were conducted in 1994 and 1995 to quantify the relation ship between simulated striped cucumber beetle, Acalymma vittatum (F.) , defoliation and yield loss in 'Carolina' cucumber. Six simulated def oliation levels (0-100%) were imposed over five time intervals in 1994 and nine simulated defoliation levels were imposed over six time inte rvals in 1995. Time intervals began at cotyledon, Ist, 2nd, or 3rd tru e-leaf, or Ist flower growth stages, and were terminated at either Ist flower or harvest. There were no significant differences among timing of defoliation treatments for continuous defoliation, and significant yield loss occurred only when defoliation was > 25% in both years. On e-time simulated insect defoliation treatments showed no significant d ifferences in timing of defoliation and significant yield loss occurre d only at > 50% defoliation. Simulated defoliation results were used t o estimate action thresholds. Results of the studies suggest that 'Car olina' cucumber can withstand high levels of defoliation before yield loss occurs, and that A. vittatum damage is primarily a concern during early plant growth stages. (C) 1998 Elsevier Science Ltd. All rights reserved.