Cold hardiness of adult western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

The cold hardiness in adult males and females of Frankliniella occidentalis (Pergande) reared at different conditions were investigated. Supercooling points (SCPs) were about -26°C in both males and females. The SCPs were not affected by the rearing conditions of photoperiod and temperature. However, the survival periods of males and females at low temperatures from -15°C to 5°C were predominantly affected by rearing temperatures. Males and females reared at 15°C survived longer at the low temperatures than those reared at 20°C. Females survived for much longer than males at the low temperatures except -15°C. Furthermore, the survival periods of males and females at the low temperatures were affected by water and food applications. However, the effects were smaller in both males and females at 0°C from -5°C for 12 h to +5°C for 12 h than 5°C, especially less water effect was observed in males at 0°C. Males and females given food maximally survived for about 30 d and 40 d at 0°C, and about 40 d and 60 d at 5°C, respectively. These results show that F. occidentalis can overwinter only in relative mild winter or artificial conditions.