Aphid-killing bacteria: diversity, origin, mechanisms and biocontrol potential.

Aphids are among the most destructive agricultural pests worldwide and cause substantial yield losses through direct feeding, virus transmission, and indirect plant damage. While chemical insecticides have been the primary control strategy of aphids, increasing resistance, environmental concerns, and regulatory restrictions have prompted the search for alternative approaches. In recent years, aphid-killing bacteria have emerged as a promising yet underexplored group of biological control agents. Growing evidence shows that aphids are susceptible to a diverse range of bacteria spanning multiple taxonomic groups. Many of these bacteria originate from plant-associated environments or from the aphids themselves and employ different mechanisms to reduce aphid survival and fitness, including toxin production, immune suppression, and disruption of aphid symbioses. This mini-review summarizes current knowledge on the diversity, ecological origins, and modes of action of aphid-killing bacteria. We further discuss their potential advantages, limitations, and challenges for practical implementation in biological control and integrated pest management strategies of aphids. Improved understanding of these bacteria may facilitate their application as effective, sustainable alternatives to chemical insecticides for aphid management.