Temperature-activity relationships in Meligethes aeneus: implications for pest management

Area of Science:

• Agricultural Entomology
• Pest Management
• Insect Ecology

Background:

• Insecticide resistance in pollen beetles (Meligethes aeneus F.) necessitates improved pest management strategies for oilseed rape (Brassica napus L.).
• Current risk assessment relies on temperature thresholds and economic damage levels, which show significant variation due to climatic factors and plant compensation.
• Understanding the direct impact of temperature on key beetle activities is essential for accurate risk prediction.

Purpose of the Study:

• To investigate the effect of controlled temperatures on the flight, feeding, and oviposition activities of the pollen beetle (Meligethes aeneus F.).
• To establish precise temperature thresholds for pollen beetle flight and activity relevant to oilseed rape cultivation.

Main Methods:

• Controlled laboratory experiments were conducted to observe pollen beetle flight initiation and duration.
• Video observations and escape from release vials were used to quantify flight propensity at different temperatures.
• Feeding and oviposition rates on oilseed rape flower buds were measured across a range of temperatures (6-20°C).

Main Results:

• Pollen beetle flight propensity followed a sigmoid curve, with 10, 25, and 50% flight thresholds identified between 12.0-16.2°C.
• Slightly higher flight thresholds were observed in older beetles, indicating an age-related effect.
• Significant positive correlations were found between temperature (6-20°C) and the rates of pollen beetle feeding and oviposition on oilseed rape buds.

Conclusions:

• The established temperature-activity relationships can enhance the accuracy of pollen beetle migration risk assessments.
• These findings will aid in refining weather-based decision support systems for oilseed rape pest management.
• Modulating crop damage thresholds based on observed bud damage rates, influenced by temperature, is recommended.