TIMING INSECTICIDE APPLICATIONS FOR SQUASH BUG (HETEROPTERA, COREIDAE) MANAGEMENT - IMPACT ON SQUASH BUG ABUNDANCE AND SUMMER SQUASH YIELDS

Five insecticide regimes were compared in plots of spring-planted summer squash Cucurbit pepo L., cv. 'Hyrific', in 1987 and 1988 to investigate the impact of spray timing on seasonal abundance of squash bugs, Anasa tristis (De Geer), and associated plant yield responses. Numbers of adults and nymphs did not increase to damaging levels before flowering of squash plants; however, feeding by squash bugs during flowering and fruit set significantly reduced fruit production. Yield losses were directly related to timing of insecticide applications and to the duration and magnitude of squash bug infestation during fruit production. Numbers of nymphs and adults during harvest periods were greatest in control plots, inducing high rates of plant mortality and reducing yields by more than 50%. Populations were lowest in treatments receiving weekly cypermethrin applications. Precisely timed applications based on estimates of low egg mass densities and degree day accumulations prior to harvest were effective in maintaining populations below damaging levels.