Overwintering biology of the carob moth Apomyelois ceratoniae (Lepidoptera: Pyralidae)

Abstract

The pomegranate fruit moth, Apomyelois ceratoniae (Zeller), is the most important pest of pomegranate orchards in Iran, where infestations lead to 20%–80% fruit loss. A. ceratoniae overwinters as larvae in several instars. The success in overwintering determines the fruit loss in the following season, thus overwintering physiology of A. ceratoniae could provide insights into population prediction. To this end, overwintering strategy and some seasonal physiological and biochemical changes were investigated in the field-collected larvae of A. ceratoniae. The lowest supercooling point was recorded in November (−14.6 ± 0.9 °C) and the highest in both October and March (−10.2 ± 0.9 °C). The median lethal temperature (LT₅₀) of larvae was higher than supercooling point, suggesting that A. ceratoniae is chill-susceptible. Overwintering larvae had slightly higher concentrations of glycerol and sorbitol compared to summer larvae. There were no significant seasonal changes in body water content or hemolymph osmolality. Current winter temperatures in Iranian orchards are higher than the cold tolerance thresholds of A. ceratoniae, suggesting that overwintering mortality is not a key factor in determining A. ceratoniae populations.

Keywords:

• cold hardiness
• cryoprotectants
• osmolality
• supercooling point
• water content

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was financially supported by Iran National Science Foundation (project number 91003418).