Introduction

In the intricate web of ecological relationships, the interaction between ants and plant hoppers feeding on tree sap stands out as a classic example of multitrophic interactions. This relationship is not just a simple two-way exchange but involves multiple layers of influence across different trophic levels, including plants, herbivorous insects, and predatory or mutualistic ants.

What Happens in This Interaction?

• Plant hoppers feed on the sap of trees, extracting nutrients and excreting a sugary substance called honeydew.

• Ants are attracted to this honeydew, which serves as a rich and reliable food source for them.

• In exchange, ants protect plant hoppers from predators and parasitoids, ensuring the continued production of honeydew.

• The tree is also indirectly affected: while plant hoppers may harm the tree by feeding on its sap, the presence of ants can reduce the impact of other, more damaging herbivores and sometimes even benefit the plant by keeping its surface clean of excess honeydew and mold1234.

Why Is This a Multitrophic Interaction?

A multitrophic interaction involves more than two trophic levels (e.g., plant, herbivore, and predator/mutualist). In this case:

• First trophic level: The tree (producer)

• Second trophic level: Plant hoppers (herbivores)

• Third trophic level: Ants (mutualists/protectors)

The ants, by interacting with both the plant hoppers and indirectly with the tree, create a network of effects that ripple through the ecosystem. This relationship is not just mutualistic between ants and plant hoppers but also impacts the broader community structure and plant health34.

Scientific Evidence

• Studies confirm that ants do not prey on plant hoppers in this context but instead form a mutualistic relationship with them23.

• This interaction is described as “obligatory mutualism” for some species, meaning both ants and plant hoppers depend on each other for survival1.

• The presence of ants can alter the abundance and behavior of other herbivores and predators on the plant, demonstrating the multitrophic nature of the relationship4.

Conclusion

The correct interpretation is:

(3) This is an example of a multitrophic interaction.

This relationship exemplifies the complexity of ecological networks, where the actions of one species can influence multiple others across different trophic levels, shaping the structure and function of entire ecosystems.