WHEN DEFENSE BACKFIRES - DETRIMENTAL EFFECT OF A PLANTS PROTECTIVE TRICHOMES ON AN INSECT BENEFICIAL TO THE PLANT

The plant Mentzelia pumila (family Loasaceae) has leaves and stems den sely covered with tiny hooked trichomes. The structures entrap and kil l insects and therefore are most probably protective. But they are als o maladaptive in that they incapacitate a coccinellid beetle (Hippodam ia convergens) that preys upon an aphid enemy (Macrosiphum mentzeliae) of the plant. The adaptive benefit provided by the trichomes is evide ntly offset by a cost.