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Why Small Animals Are Huge for Conservation

The tiniest of creatures keep the fabric of our world together, but are often overlooked

Ladybugs
Ladybugs stop pests from eating our food and destroying crops. (Flickr/Inhabitat)
By Michael Samways, The Conversation
SMITHSONIAN.COM 

Humans like to think that they rule the planet and are hard-wired to do so. But our stewardship has been anything but successful. The last major extinction event, 66 million years ago, was caused by a meteorite. But the next mass extinction event, which is under way right now, is our fault.

Geologists have even given this era in the history of the Earth a new name to reflect our role: the Anthropocene, the age of humans.

It’s the first time in the history of the Earth in which one species dominates all the others. These “others” numbers are probably around 10 million. The vast majority are the invertebrates, the animals without backbones. Not all are so small—some squids and jellyfish are several meters long or across.

Most, though, are small and unassuming. And they are hidden in plain view. They are busy maintaining the fabric of the world around us. They are the warp and weft of all natural systems. They make the soil, pollinate the flowers, spread seeds and recycle valuable nutrients back into the soil. They are also food for many birds that are so loved, and keep other small animals in check by eating or parasitising them.

Yet most of us are oblivious of the many roles of these mostly small, even tiny, animals. If all their services were gone tomorrow, many plants would soon go extinct. Crops would be lost overnight. Many birds would die from lack of food, and soil formation would largely halt. The knock-on effects would also be huge as food webs collapse, and the world would quite literally fall apart.

So how can all the small animals be saved?

Future generations depend on these small animals, so the focus must be on increasing awareness among the young. Research has shown that children are intrinsically interested in what a bee, cricket, butterfly or snail is. Their small world is at the same level as this small world of insects and all their allies without backbones. Yet strangely, while we care about our children, we care so little for all the small creatures on which our children depend on now and into the future.

Children must be shown that the bee is keeping the flowering plant species alive and well, the grasshopper is recycling scarce food requirements for plants, the millipede is making the soil, and the ladybug is stopping pests from eating all our food. Showing children that this miniature world is there, and that it’s crucial, is probably one of the best things to do to help them survive the future in this world of turmoil.

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Over the past 400 million years, evolution has produced a wide variety of arthropod
species adapted to their environments. About 1 million of the 1.4 million described
animal species on earth are insects, and millions more are believed to exist. Contrary
to popular belief, of the 1 million described insect species, only 5 000 can be considered
harmful to crops, livestock or human beings (Van Lenteren, 2006).
nsects deliver a host of ecological services fundamental to the survival of humankind.
For instance, insects play an important role in
plant reproduction
. An estimated
100 000 pollinator species have been identified and almost all of these (98 percent)
are insects (Ingram, Nabhan and Buchmann, 1996). Over 90 percent of the 250 000
flowering plant species depend on pollinators. This is also true for three-quarters
of the 100 crop species that generate most of the world’s food (Ingram, Nabhan and
Buchmann, 1996). Domesticated bees alone pollinate an estimated 15 percent of these
species. The importance of this ecological service for agriculture and nature more
generally is undisputed.
Insects play an equally vital role in
waste biodegradation
. Beetle larvae, flies, ants
and termites clean up dead plant matter, breaking down organic matter until it is fit
to be consumed by fungi and bacteria. In this way, the minerals and nutrients of dead
organisms become readily available in the soil for uptake by plants. Animal carcasses,
for example, are consumed by fly maggots and beetle larvae. Dung beetles – of which
there are about 4 000 known species – also play a significant role in decomposing manure.
They can colonize a dung heap within 24 hours, preventing flies from developing on
them. If the dung remains on the soil surface, about 80 percent of the nitrogen is lost
to the atmosphere; the presence of dung beetles, however, means carbon and minerals
are recycled back to the soil, where they further decompose as humus for plants. When
cattle were introduced to Australia in 1788, waste biodegradation became an immediate
problem, as endemic dung beetles were simply insufficient to decompose the increased
amounts of manure. Australian dung beetles had adapted to the dung of marsupials (e.g.
kangaroos), which differs from bovine dung in various ways, including in size, texture
and water content (Bornemissza, 1976). The Australian Dung Beetle Project was initiated
to solve the problem, and dung beetles were introduced to the continent from South
Africa, Europe and Hawaii (of 46 introduced species, 23 established).
Beneficial fauna, including insects, buttress the natural resistance of agro-ecosystems.
Pest insects have a large array of natural enemies, predators and parasitoids, keeping them
under economic threshold levels. However, by using insecticides, vulnerable beneficial
insects can be killed quicker than the targeted pest insect. One reason for this is that
the target pest is often better protected (such as stem borers by the stem and mites
by webs) than beneficial insects, which need to forage. Following the application of a
synthetic pesticide, the population of the pest insect first decreases but then increases
exponentially, because the pest insect can now develop without being constrained
by attacks from beneficial insects. A notorious example of this is the outbreak of the
brown planthopper in rice instigated by the use of pesticides (Box 2.1) (Heinrichs and
Mochida, 1984).
Virtually all agro-ecosytems benefit from insects because they can
naturally control
harmful pest species
. The number of insects that parasitize or prey on other insects is
vast. Ten percent of all insects are parasitoids (Godfray, 1994). Entire orders of insects –
such as Odonota (dragonflies) and Neuroptera (net-winged insects such as lacewings and
antlions) – are predators. A large percentage of true bugs (Hemiptera), beetles (Coleoptera),
flies (Diptera) and wasps, bees and ants (Hymenoptera) are also predators. The number
of beneficial insect species in the average agro-ecosystem typically far outweighs the
number of harmful insect species. For example, in a study carried out in a single agro-
ecosystem in rice fields in Indonesia, Settle
et al.
(1996) recorded 500 beneficial insect
species and 130 pest species. Another 150 insect species were deemed “neutral” since they
do no attack rice, although they served a very important role in the survival of predators
when rice was lacking. Beetles have also been used to control water hyacinth invasions.
Snout beetles (
Neochetina
spp.), imported from Australia, successfully controlled the
water hyacinth in Lake Victoria (Wilson
et al.
, 2007).
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