Temperature regimens effect on Ephestia cautella Walker (Pyralidae: Lepidoptera) biology

ABSTRACT Ephestia cautella Walker, seriously damage dates quality both in the field and storage conditions. Temperature regimens effect on E. cautella biology under laboratory conditions was studied. E. cautella eggs were from a culture in the Economic Entomology Research Unit, Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia. Upon hatching, neonates were divided into three groups, each had 4- replicates, with 40 neonates. Groups were transferred to their respective temperature regimens: 5, 25, and 35 °C; with 65 ± 5% RH, and a photoperiod of 15:9 (L:D). Biological parameters such as: number and duration of larval instars; rate of surviving larvae, pupae, and adult; life span; fecundity; and fertility were evaluated. Temperature regimens exhibited a significant impact on E. cautella biological parameters. At 5°C, there was neither egg hatching nor larval or pupal survival. 100% mortality, among all larval instars exposed to 5°C, was observed. E. cautella reached 5^th and 6^th larval instars at 25 and 35°C, respectively. Early larval instars had comparatively shorter span at 25 and 35°C temperature regimens when compared with later instars. Significantly longer larval span was recorded at 35°C. However, pupal and adult spans of both male and female were significantly longer at 25°C. Among the three temperature regimens, 25°C was highly favorable for fecundity, egg hatchability, and overall survival of entire life stages. Its concluded that storage at lower temperatures can save dates from losses inflicted by E. cautella.

KEY WORDS Ephestia cautella, biology, temperature, larval instars, date storage