EFFECT OF TEMPERATURE ON DEVELOPMENTAL RATE AND FECUNDITY OF THE PEAR PSYLLA, PSYLLA PYRICOLA (HOMOPTERA: PSYLLIDAE)

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Abstract
At constant temperatures between 10.0° and 32.2°C with 16 h photoperiod development of eggs and nymphs was slowest at 10.0° (61.8 days av.) and most rapid at 26.7°C (27.0 days av.). Mortality of eggs and nymphs was moderate (43.7%) at 10.0°, least (24.2%) at 21.1°, and 100% at 32.2°C. Between 15.6° and 35.0°C, 16 h photoperiod, fecundity of winter form adults was greatest (486.3 eggs av) at 15.6° and lowest (0.0 eggs) at 35.0°C. For summer form adults fecundity was moderate (212.4 eggs av.) at 15.6°, maximum (444.9 and 447.3 eggs av., respectively) at 21.1° and 26.7°C, and least (2.8 eggs av.) at 35.0°C. Longevity of male and female winter and summer forms was greatest at the low temperature and least at the high temperature. These data are discussed with relation to field observations of natural pear psylla populations and control programs.