Week 4: Keystone Species & Food Web Architects

Hello, I'm Marjen, a passionate environmental science student from Swinburne University. Within tropical ecosystems, insects play a pivotal role as keystone species, actively contributing to the preservation of stability and biodiversity in these intricate and diverse environments. In the following discussion, we will further explore their importance and offer additional insights into their functions within the tropical ecosystem.

Fig Wasps and Fig Trees

Fig wasps serve as a prominent illustration of keystone species within tropical ecosystems. They engage in a mutualistic association with fig trees, taking on the vital roles of pollinating and fertilizing the figs. In return for their services, fig wasps deposit their eggs inside the fig's fruit (Britannica, 2019). The absence of fig wasps would result in the inability of fig trees to reproduce, triggering a domino effect throughout the entire ecosystem. These fig trees frequently serve as a source of nourishment and refuge for a wide variety of organisms, encompassing birds, mammals, and various other insects. The scarcity of fig wasps could potentially drive the decline or even the extinction of these interdependent species.

Fig 1: Lifecycle of Fig Wasp & Pollination of Fig Trees (Britannica, 2019).

Predatory Insects and Herbivore Control

In tropical ecosystems, a profusion of herbivorous insects abounds, setting the stage for the involvement of predatory insects. Mantises, dragonflies, assassin bugs, and a diverse array of other insect predators’ step in to regulate herbivore populations. By preying on herbivores, they avert the risk of these insects overgrazing on plants, which could otherwise lead to substantial damage and ecological imbalances (Uhey and Hofstetter, 2021). This predatory activity sustains the overall well-being of the ecosystem and safeguards the longevity of plant life.

Parasitic Insects and Biodiversity Regulation

Within tropical ecosystems, parasitic insects, exemplified by parasitic wasps, exercise their own indispensable function in biodiversity management. These wasps lay their eggs inside other insects, utilizing them as hosts for the subsequent development of wasp larvae. According to Uhey and Hofstetter (2021), this parasitic association serves as a mechanism for controlling the populations of various insects, effectively preventing outbreaks that might otherwise harm plant species. It constitutes a fragile yet essential equilibrium that fosters the vitality of the ecosystem.

Insects may often be overlooked or regarded as pests, but they are, in fact, the unsung heroes of tropical ecosystems. Understanding and appreciating the intricate relationships between insects and their environments is essential for the preservation of tropical biodiversity and the overall health of these vital ecosystems. So, the next time you find yourself in a tropical paradise, take a moment to observe the small but mighty insects, for they are the true architects of this magnificent natural world.

References

Britannica 2019, ’Insect: Fig Wasp’, Britannica Encyclopaedia, viewed 18 October 2023, < https://www.britannica.com/animal/fig-wasp >

Uhey, DA & Hofstetter, RW 2021, ‘From Pests to Keystone Species: Ecosystem Influences and Human Perceptions of Harvester Ants (Pogonomyrmex, Veromessor, and Messor spp.)’, Annals of the Entomological Society of America, viewed 17 October 2023, < https://academic.oup.com/aesa/article/115/2/127/6427367 >