Long-term trends in migrating Brassicogethes aeneus in the UK

Area of Science:

• Agricultural Entomology
• Pest Management Science
• Crop Protection

Background:

• The pollen beetle (Brassicogethes aeneus) is a significant pest of oilseed rape (Brassica napus), causing substantial yield losses.
• Predicting population dynamics of this pest is challenging due to spatial and temporal variations in phenology and abundance.

Purpose of the Study:

• To investigate long-term trends in pollen beetle populations.
• To explore the relationship between pollen beetle abundance and oilseed rape cultivation area.
• To understand inter-generational population dynamics.

Main Methods:

• Generalized additive models were used to analyze annual, seasonal, and monthly pollen beetle counts from suction-traps.
• Random forest models were employed to examine within-year, inter-generational relationships.
• Data spanned a significant time period for trend analysis.

Main Results:

• Pollen beetle counts and oilseed rape area both increased significantly, but were not directly correlated.
• Immigrating pollen beetle population size was influenced by the previous summer's population and winter temperatures.
• A positive feedback mechanism was identified.

Conclusions:

• Pollen beetle populations continue to rise in the UK, posing ongoing control challenges.
• Forecasting spring migration is potentially feasible using suction-trap data and previous summer counts.
• This forecasting could inform pest control strategies for oilseed rape.