How can bark beetles kill trees?

How can bark beetles kill trees?

• A. Tunneling and girdling trees
• B. Defoliating leaves
• C. Causing root rot
• D. Feeding on fruit

Answer: (A)

Bark beetles kill trees by tunneling under the bark and girdling the trunk, which blocks the transport of water and nutrients through the tree’s vascular system. They bore into the inner bark to create galleries in the phloem and cambial tissue; when a ring of bark is removed or damaged, the tree can’t move sugars from the leaves to the roots or to new growth. That disruption weakens the tree, and stressed trees are especially vulnerable to mortality from sustained infestations and associated pathogens carried by the beetles. Defoliating leaves is a different kind of damage typical of foliage-feeding insects, not the main way bark beetles kill trees; root rot involves pathogens in the soil, and feeding on fruit isn’t characteristic of bark beetles. The key point is that the lethal effect comes from tunneling and girdling the bark, interrupting the tree’s nutrient transport.

Bark beetles kill trees by tunneling under the bark and girdling the trunk, which blocks the transport of water and nutrients through the tree’s vascular system. They bore into the inner bark to create galleries in the phloem and cambial tissue; when a ring of bark is removed or damaged, the tree can’t move sugars from the leaves to the roots or to new growth. That disruption weakens the tree, and stressed trees are especially vulnerable to mortality from sustained infestations and associated pathogens carried by the beetles.

Defoliating leaves is a different kind of damage typical of foliage-feeding insects, not the main way bark beetles kill trees; root rot involves pathogens in the soil, and feeding on fruit isn’t characteristic of bark beetles. The key point is that the lethal effect comes from tunneling and girdling the bark, interrupting the tree’s nutrient transport.