A multi-year dormancy strategy in a cabbage beetle population in southeastern China

Area of Science:

• Entomology
• Insect Ecology
• Dormancy Biology

Background:

• The cabbage beetle, *Colaphellus bowringi*, in southeastern China displays complex adult development with four distinct pathways.
• Understanding multi-year emergence patterns of diapausing individuals is crucial for pest management but remains poorly documented.

Purpose of the Study:

• To monitor adult emergence patterns of diapausing *C. bowringi* over several years.
• To assess the impact of diapause-inducing temperature and photoperiod on prolonged diapause incidence.
• To elucidate the multi-year dormancy strategy of *C. bowringi*.

Main Methods:

• Field monitoring of adult emergence patterns over multiple years.
• Seminatural experiments testing the influence of controlled temperatures (22, 25, 28°C) and photoperiods (12:12h, 14:10h L:D) on diapause duration.
• Statistical analysis using log-rank tests to compare diapause durations.

Main Results:

• Diapause duration varied from months to 5 years, with 25.9%-29.2% exhibiting prolonged diapause.
• Adult emergence consistently occurred in spring (mid-February to March) and autumn (late August to mid-October), coinciding with host plant availability.
• Low temperature (22°C) combined with a long photoperiod (14:10h L:D) resulted in the longest diapause, while 22°C and a short photoperiod (12:12h L:D) induced the highest proportion of prolonged diapause.

Conclusions:

• *C. bowringi* employs a multi-year dormancy strategy for survival against environmental fluctuations and risks.
• Temperature and photoperiod are key environmental cues regulating the duration and incidence of prolonged diapause in this species.
• This complex dormancy behavior has significant implications for the population dynamics and management of cabbage beetles.