phloemfeeders

Phloem feeders are herbivorous insects and other organisms that obtain nutrients by piercing plant tissues to reach the phloem, the vascular tissue that transports sugars and other solutes from photosynthetic sources to sinks. They include many hemipterans such as aphids (Aphidoidea), psyllids (Psylloidea), whiteflies (Aleyrodoidea), scale insects (Coccoidea), and mealybugs, as well as some planthoppers.

Feeding involves specialized mouthparts called stylets that navigate between plant cells to reach sieve elements of the phloem. Phloem sap is rich in sugars, amino acids, and minerals and is transported under positive pressure from source tissues to growing or storage sinks. Phloem feeders often feed in colonies and continuously excrete honeydew, a sugary waste product that can promote sooty mold on leaves and fruit.

Impact on plants can be direct or indirect. Direct effects include reduced vigor, leaf curling, stunting, and distorted growth due to nutrient removal. Indirect effects arise from honeydew-associated sooty mold and, more broadly, from the transmission of plant pathogens. Many phloem-feeding insects are vectors of viruses, phytoplasmas, and certain bacterial pathogens, which can cause significant crop losses.

Ecology and management considerations emphasize integrated approaches. Phloem feeders frequently occur in dense patches on leaves and stems, attracting natural enemies such as parasitoid wasps (for example, Aphidiinae), lady beetles, lacewings, and predatory bugs; ants may tend honeydew-producing colonies. Management typically combines monitoring, biological control, cultural practices to reduce suitable habitat, and targeted chemical or botanical controls when necessary, aiming to minimize disruption of beneficial organisms.