Effect of constant temperatures on development of the walnut husk fly, Rhagoletis completa

Abstract

AbstractThe developmental rates of various life stages of Rhagoletis completa Cresson (Diptera: Tephritidae) were determined in the laboratory at seven different constant temperatures: 8, 12, 16, 20, 24, 28, and 32 ± 1°C, RH 80 ± 10%, photoperiod L16:D8. Preoviposition developmental rate was fastest at 28°C (10 ± 1 days, mean ± SD) and slowest at 12°C (26 ± 1 days). About 83% of the females deposited eggs at 20 and 24°C and only 25% oviposited at 32°C. Females laid the highest number of eggs at 24°C and the lowest at 8°C. Egg development increased with increasing temperatures up to 28°C, then declined. The fastest egg development was noticed at 28°C (55 ± 1 h) and slowest at 8°C (389 ± 2 h). Over 90% egg hatch was observed at temperatures between 12 and 32°C, but decreased to 73% at 8°C. Larval development was fastest also at 28°C (20 ± 0.2 days). Over 65% pupation was recorded at 20 and 24°C, but decreased to 15% at 32°C and 12% at 8°C. Pupal development was most rapid at 24°C (53 ± 1 days) and slowest at 8°C (162 ± 2 days). More than 70% of adult emergence was noticed in treatments between 16 and 24°C but decreased to 20% at 8°C. Based on a linear regression model of temperature‐development rate relationship, the lower developmental thresholds were determined to be 6.6, 5.3, 2.9, and 5°C for preoviposition, egg, larval, and pupal stages, respectively. Based on a non‐linear developmental rate model, the upper developmental thresholds were 34°C for preoviposition, egg, and larval stages and 30°C for pupal stage.