Just happened to do some browsing over at Wild Light (http://www.bugdreams.com) and came across some incredibly photogenic insects that got the wheels turning. At first I was wondering if we have forgotten about this heavily weighted class of biomass, but then I realized a few buzzing pollinators have occupied the headlines over the past few years in regards to declining numbers…you know the story. And their [insects] importance to a fully functioning ecosystem is utterly undeniable so here’s the spin.
As populations continue to cross the globe with non-native animals and plants in tow we have indirectly introduced foreign invaders and under the guise of agro-science, for instance, have unleashed directly a host of other exoskeleton intruders throughout the past. But remember the native insects; those evolutionarily adapted to certain habitats and prey and kept in balance by predators?
As native plants are ousted by competitive invasive species, it is not only the birds and mammals that have to contend with a changing habitat but those so-called pesky insects we are always trying to avoid. So what effect does encroaching invasive plants have on insect abundance, and the food web? Against my initial best guess, according to researchers at the University of Bristol, oddly enough insect abundance was not driven lower with the decline of native plant species. However, a happy ending it was not as biodiversity suffered greatly.
In one study, larger, specialized, native and more diverse insect species were replaced by smaller invasive generalists that effectively balanced out the biomass load. This change in biodiversity limited the range of species available for predators, and introduced seasonal shifts. Thus, predators that relied on a once predicted insect emergence were unable to find food at pivotal times such as the breeding season. It is not just about quantity but quality when it comes to insects, at least as seen by birds, bats, and all the other creatures that depend on this class for sustenance.
As per Ruben Heleno, University of Bristol, “Given that all insects are not equally useful as prey, insect biodiversity is likely to provide a more meaningful picture of the impact of alien plants on higher trophic levels.”
The ripple effect from plant to insect to animal travels the food web and can ultimately create an ecosystem-wide transformation from which we, and especially native wildlife, cannot recover . By the way, besides changing insect dynamics, increasing non-native plants can also result in the introduction of different seed patterns that may or may not coincide with the lifecycles of native wildlife.