South Africa has been ranked the third most biologically diverse country on the planet based on an index of species richness and endemicity for higher plants and vertebrates (World Conservation Monitoring Centre, 1992). Only 6% of the country is currently formally conserved, and outside of reserves many habitats are threatened by urbanisation, industrialisation, agriculture, pollution and overharvesting. The Department of Environmental Affairs & Toursim of South Africa are currently developing a National Biodiversity Strategy and Action Plan to address biodiversity conservation in South Africa. In order to succeed, this and other biodiversity activities require data on the country’s biodiversity.
While there is generally a fairly sound understanding of the diversity of vertebrates and higher plants in South Africa, and there is generally at least some knowledge of species distribution and conservation status for these taxa, this is not the case for the largest component of biodiversity. Invertebrates may comprise as much as 95 % of biodiversity (Myers et al, 2000), but they are disproportionately poorly known. This is particularly true in South Africa, where invertebrates have been overlooked in favour of the spectacular game and bird fauna of the country. Invertebrates are essential to ecosystem functioning and also provide the foundation for economic activities that generate disposable income (agriculture, forestry, horticulture, waste disposal, ecotourism) (Savage, 1995; Simpson & Cracraft, 1995). In South Africa there are vast gaps in our understanding of what the invertebrate component of our biodiversity consists of, where it occurs, which species are threatened, and where these occur. This leaves them largely unprotected and unappreciated.
Current biodiversity conservation activities are based on a few groups for which adequate data exist. The assumption is that patterns of diversity, endemism and distribution for flowering plants will reflect those for invertebrates, and management practices based on vegetation and / or large mammals will also protect invertebrates (Myers, et al, 2000). These assumptions have not been adequately tested, and there are indications that in some cases they are not true. Management practices for vegetation, large mammals and tourism, such as burning regimes, control of alien vegetation, malaria control programmes in conservation areas may actually threaten invertebrate diversity, including large numbers of endemic species. Without rigorous data, these issues cannot be addressed or even recognised by land managers.
Existing data on South African invertebrates indicate unusually high levels of endemism – ranging from 50 to 90% for different taxa (unpublished data collected from invertebrate specialists based in South Africa). This means that this fauna should be conserved for their contribution to global biodiversity, as well as their crucial roles in ecosystem functioning. In addition, invertebrates are largely ignored in the ecotourism industry, yet many of the larger, more spectacular, interesting and rare invertebrates have potential for incorporation into community ecotourism endevours.
South Africa has several large museums which house large collections of invertebrates, many of which have been electronically databased. There is also considerable capacity to identify a range of invertebrate taxa. There are still, however, several problems with integrating invertebrates into biodiversity conservation.
* Most of the existing data were collected on an ad hoc basis with no measurement of sampling intensity (Slotow & Hamer, 2000). This means that we have no indication of abundance, rarity, or accuracy in terms of species richness, and these factors make it almost impossible to nominate species for Red Listing.
* Many areas remain very poorly known in terms of invertebrates which means that invertebrates are excluded from management activities in protected areas, or threatened in terms of future land use practices if these areas are unprotected.
* Many of the records are old (pre 1960) and do not contain accurate locality or habitat data, which makes extrapolation of species distributions impossible.
* Very few areas or taxa have been surveyed intensively. These types of data are essential for understanding the significance of different areas for biodiversity conservation, or for examining patterns of congruency in richness between different taxa, or for identifying potential biodiversity indicators for different habitats.
* Most decision makers and the general public are not aware of the enormous wealth of diversity of South Africa’s invertebrates or of the critical need to conserve this component of the fauna. Conservation agencies are, however, becoming increasingly aware of this need and are requesting data for priority areas. In many cases, however, this simply does not exist, or it is totally inadequate.
The project aims to address these issues for a suite of taxa in key areas of South Africa, in order to enable improved biodiversity conservation.
It is necessary to focus on priority geographic areas, including government priorities, at least in the short term. These areas have been selected on the basis of several criteria, most important of which are:
* The development of new conservation areas, for which baseline information on biodiversity is required for future management plans, marketing and ecotourism, including community tourism ventures
* Formally conserved areas where it is suspected that management practices, in particular, burning, may be negatively impacting on biodiversity
* Formally conserved areas which have low priority or conservation value in terms of biodiversity, but which are expected to have exceptionally high levels of species richness and endemicity for invertebrates (eg. the Mkuze area including both a formal reserve and private land)
* Private land where future land use may threaten biodiversity, but data on biodiversity could influence land owners to conserve habitats (for example, the Mkuze area).
* Areas with high habitat / vegetation diversity (for example Mkuze Game Reserve which has Sand Forest, Riverine Forest, open savanna woodland, and a variety of waterbodies).
The enormous diversity and abundance of invertebrates is probably the most important reason for their omission from biodiversity conservation activities. This problem can be addressed by selecting a suite of focus taxa representing a range of:
* Functional groups, including pollinators, predators, detritivores, saprophages, grazers, scavengers.
* Habitat specialists: including terrestrial and freshwater organisms, and at a finer scale, different inhabitants of different vegetation types and of different terrains, and for freshwater systems, specialists of streams, rivers and ephemeral habitats.
* Niche specialists: soil, leaf litter, arboreal, aerial, benthic, planktonic animals.
* Mobilities: including easily dispersed and mobile animals and those that are flightless and / or have limited mobility because of physiological constraints.
* Life history patterns
* Body sizes
Additional selection criteria are the existence of some taxonomic knowledge, and the availability of expertise willing to commit to the project.
Although selecting a suite of taxa is possible for this project, it is recognised that the available resources do not allow the sampling of a wide range of taxa to monitor conservation and management impacts across South Africa over a sustained period. Tools to deal with invertebrates are required (Oliver & Beattie, 1996). These include the widely discussed, but poorly researched concepts of surrogates, biodiversity indicators and congruency.
The conservation of invertebrate biodiversity cannot be effective based on scientific knowledge alone. There needs to be an awareness and acceptance of the significance of invertebrates and their enormous contribution to biodiversity among decision makers, conservationists and the general public before data are incorporated into planning and management. South Africa has a shortage of invertebrate taxonomists, and a lack of capacity amongst conservation graduates and practitioners to manage and monitor invertebrates diversity. It is likely that these are not uniquely South African problems. Thus the project also aims to:
* Increase public awareness of and appreciation for invertebrate biodiversity.
* Increase capacity to survey, process, and identify invertebrates and manage invertebrate data, as well as to monitor and manage invertebrates.
80 000 insects are known to occur, many of which are endemic. There are many more as yet undescribed species.
There is no general agreement on the details of how different groups of invertebrates are related.
Phylum Annelida (Segmented Worms)
Phylum Nematode (Round worms)
Phylum Onychophora (Velvet Worms) click
Phylum Arthropoda (Insects, centipedes, millipedes, crustaceans, arachnids) - All arthropods have an exoskeleton that covers a body divided into segments, and all have jointed legs.
World Wide: 17 Classes, 99 Orders, 2 140 Families
With around one million named species and perhaps several times that number unnamed, insects account for a great majority of the species of animals on earth. Insects are a tremendously successful group and can be found in almost all terrestrial and freshwater habitats, from the driest deserts to freshwater ponds, from the canopy of a tropical rainforest (where their diversity is unbelievably great) to the arctic wastes. A few species are even marine. Their feeding habits are similarly varied; almost any substance that has nutritive value is eaten by some group of insects.
Insects also show huge variety in shape and form. Almost the only condition their group does not attain is very large body size. A number of features, however, are shared by most kinds of living insects. In addition to the general characteristics of uniramians, these include a body composed of three tagmata, a head, thorax, and abodmen; a pair of relatively large compound eyes and usually three ocelli located on the head; a pair of antennae, also on the head; mouthparts consisting of a labrum, a pair of mandibles, a pair of maxillae, a labium, and a tonguelike hypopharynx; two pairs of wings, derived from outgrowths of the body wall (unlike any vertebrate wings); and three pairs of walking legs.
Insects have a complete and complex digestive tract. Their mouthparts are especially variable, often complexly related to their feeding habits. Insects "breathe" through a tracheal system, with external openings called spiracles and increasingly finely branched tubules that carry gases right to the metabolizing tissues. Aquatic forms may exchange gases through the body wall or they may have various kinds of gills. Excretion of nitrogenous waste takes place through Malpighian tubules. The nervous system of insects is complex, including a number of ganglia and a ventral, double nerve cord. The ganglia are largely independent in their functioning; for example, an isolated thorax is capable of walking. Yet ganglia also use sensory output. A grasshopper with one wing removed can correct for this loss and maintain flight, using sensory input from its brain. Sense organs are complex and acute. In addition to ocelli and compound eyes, some insects are quite sensitive to sounds, and their chemoreceptive abilities are astounding.
Insects are dioecious and fertilization is internal in most. The ways in which mating is accomplished, however, are incredibly variable; study of this variability by evolutionary biologists has greatly advanced our understanding of the evolution of behavior, social evolution, and traits such as number, size of young and patterns of investment in them. Reproduction by insects often involves a male locating a receptive female through chemicals (pheromones) released by the female. In most species, females store the sperm in a special receptacle in their abdomens; even species that lay huge numbers of eggs (in honeybees, for example, the number may be over one million), females mate only once and rely on sperm stored during that mating for the rest of their lives.
The manner in which growth is accomplished is an especially important characteristic of insects. In some, hatching eggs produce miniature adults, which to grow must shed their exoskeleton in a process called ecdyisis. In almost 90% of insect species, however, newly hatched young are completely different in appearance from adults. These larval forms usually live in different habitats, eat different foods, and assume a body form completely different from that of their parents. The larva feeds and grows, molting its skin periodically. At some point larval growth is completed, the larva stops feeding and builds a case or cocoon around itself. In this nonfeeding condition it is called a pupa or chrysalis. While so encased, the larva undergoes a complete transformation or "metamorphosis" of its body form, and a fully-formed adult emerges. Insects that experience this sort of complete change are called "holometabolous." Other species undergo a more gradual process, in which the newly hatched young are more similar to the adult but are small in size, lack wings, are sexually immature, and may differ in other, relatively minor ways as well. The young in these insects are called nymphs, and the lifestyle is referred to as "hemimetabolous."
Insects are incalculably valuable to man. Usually, we think of them in a negative context. Insects eat our food, feed on our blood and skin, contaminate our dwellings, and transmit horrible diseases. But without them, we could not exist. They are a fundamental part of our ecosystem. A brief and incomplete list of their positive roles would include the pollination of many, perhaps most higher plants; the decomposition of organic materials, facilitating the recycling of carbon, nitrogen, and other essential nutrients; the control of populations of harmful invertebrate species (including other insects); the direct production of certain foods (honey, for example); and the manufacture of useful products such as silk and shellac. Ethno-biology
The Butterflies of South Africa |
