Sap beetles

Among the most notorious representatives is the pollen beetle (Meligethes aeneus), which poses a major threat to brassica crops like oilseed rape, mustard, and broccoli. Both adult beetles and their larvae feed on the pollen, stamens, and pistils of developing buds. This feeding activity leads to bud abortion and significantly reduces the pod-setting potential of the plants.

The biological cycle of sap beetles typically involves one generation per year. Adults overwinter in the soil or leaf litter and emerge in early spring as temperatures rise. Once the host plants enter the budding stage, the females deposit eggs inside the buds. Larval development is rapid, feeding on the internal parts of the flowers before dropping to the ground to pupate.

The damage caused by these beetles is highly visible in fields. Plants may show signs of stunted growth and, most importantly, "blind" flower stalks where buds have fallen off. This infestation causes the plant to compensate by branching, which results in uneven ripening and harvest difficulties. Severe infestations can destroy the majority of the flower buds if not managed early.

Effective management requires a combination of monitoring and timely intervention. Farmers should utilize yellow water traps to track migration peaks during the budding phase. When economic threshold levels are reached, chemical control using insecticides is necessary to protect the yield. Cultural practices, such as choosing vigorous crop varieties and implementing crop rotation, are essential for reducing overwintering populations.