Conservation (Insects)

Insect conservation includes two main contexts. Insects may be conservation “targets,” whereby particular species become the focus of concern because of their perceived decline in abundance or distribution, or insects may be conservation “tools,” in which they are incorporated into broader aspects of conservation concern through their sensitivity to environmental changes and used as ” signals” to monitor or herald changes to natural environments. This role is facilitated by their high richness and diversity in most terrestrial and freshwater environments. Both contexts reflect concern over human intervention with the natural world and the desire to sustain both components (i.e., species and equivalent entities) and processes in natural ecosystems. The major roles of insects in sustaining ecosystem services and processes acknowledge their immense richness and biomass and are reflected in E. O. Wilson’s famous characterization of invertebrates as “the little things that run the world.”
Nevertheless, with few exceptions, ideas of conserving insects are difficult for many people to accept. In contrast to higher vertebrates and many vascular plants, which people accept readily as objects worthy of conservation, insects have a poor image and are more commonly viewed as objects for suppression or elimination. They are regarded broadly as pests or nuisances or by some disparaging epithet such as “bird food” (however important that categorization may be in sustaining community integrity).
Insect conservation has thus been slow to gain prominence on conservation agendas, but has a long history, mainly through focus on the more popular groups, predominantly butterflies, dragonflies, and some showy beetles. These insects are accepted widely as “worthy,” simply because people like them and regard them as harmless. It is also revealing to see the commonly polarized perceptions of “a butterfly” and “a moth” despite these being artificial segregates of the same insect order. Concerns arose over decline of particular species from the mid-19th century onward. Initial concerns, and the foundations of modern insect conservation practice, were in western Europe and North America but have expanded to encompass many parts of the world. Conservation in practice includes application of biological knowledge to manage or sustain species and other higher ecological levels, which reflects the total biodiversity and linkages that occur within the complex, imposed framework of regulation and socioeconomic needs that provides for ever-increasing human populations. “Biodiversity” encompasses both taxonomic and genetic diversity, with conservation aiming, broadly, to prevent its loss— either by the extinction of threatened or rare entities or by preventing other entities from decline to that state. As major components of biodiversity, in terms of species richness, ubiquity, and ecological variety, insects are an important and increasingly appreciated component of global conservation need.


Traditionally, most insects have been largely disregarded in conservation, on the premise that they may be secure under measures taken to conserve more charismatic taxa such as warm-blooded vertebrates. The latter are supposed widely to act as “umbrellas” for most or all coexisting species, but this idea is now recognized as oversimplistic,because many invertebrates are ecologically specialized and need detailed management of critical resources to sustain them in the face of environmental change. However, without past emphasis on vertebrates, many habitats and sites recognized as of considerable importance for insects would surely have been lost. One attraction of basing conservation on groups such as birds or mammals is simply that they are relatively well known. Their diversity is limited and tangible, most of the species are named, and many are recognizable without having to capture and kill the animals for detailed examination; their biology and habitat needs are reasonably well understood, and their distributional ranges and patterns defined. Even the numbers and population sizes of many species can be evaluated reliably. Parallels with large showy butterflies and dragonflies have led to these being referred to as “birdwatchers’ bugs,” but they contrast dramatically with most other insect groups. Uncertainties over levels of species richness, that most species are still unnamed or even uncollected, and fragmentary or nonexistent ecological and distributional knowledge provide severe impediments to defining the patterns of diversity and distributions that may constitute the template for conservation evaluation. For many insect habitats in most parts of the world, we have little idea of insect species richness and identity. Many insect species are known solely from long-dead museum specimens and may never be seen alive. Of the world’s 12 “megadiverse countries” (collectively estimated to harbor more than 70% of earth’s animal and higher plant species), only for Australia can reasonably informed approximations of the extent, distribution, and ecological features of the insect fauna be deduced sufficiently to make conservation recommendations above the universal need to safeguard natural habitats. For the far more species-rich tropical countries, the paucity of resident entomologists and differing priorities render such data very approximate and their accumulation a low priority. Costa Rica, recently subject to an internationally sponsored biodiversity inventory through its national Biodiversity Institute, is an important exception. It is salutary to reflect that a decline in individual insect species in well-known (predominantly temperate-region) faunas can arouse substantial conservation interest and action, whereas tropical habitats supporting far more insect species than the total fauna of any European country disappear rapidly.
There is little reason to doubt that numerous insect species have become extinct as a direct result of human activities during the past few decades, although most have not been documented, and that the process continues. Insects are a major component of what has sometimes been referred to as “the sixth great extinction,” considered likely to result in the loss of a substantial proportion of the world’s species within a few decades. Efforts in insect conservation are an important avenue to increasing the understanding of human impact on natural ecosystems and of the subtle steps needed to safeguard them in the face of accelerating losses. However, the complexity of the issues involved demands a clear perspective and allocation of priorities, so that limited funding and expertise can be deployed for the greatest benefit.
Developing such perspective has involved: (a) increasing fundamental documentation of patterns of insect species richness on a variety of geographical scales, perhaps streamlining the process by concentrating on selected focal taxa because of the immense difficulty of enumerating all insect groups; (b) selecting the most deserving taxa for conservation targets, based on urgency of need to prevent extinction; (c) defining and alleviating threats to taxa and to their host environments; (d) public and administrative education to communicate the importance of insects in the natural world, and hence the need for their conservation; and (e) evaluating the contributions of insects in broader conservation activities. These parameters recognize that, despite ethical problems with any such selection, the diversity of insect species is such as to necessitate some form of “triage” in selecting the most deserving species for management and recovery action. One consequence has been a tendency to increase the scale of conservation concern; whereas single species are the most popular conservation targets, because they are defined tangible entities to which people can relate easily, their value as “flagships” or “umbrellas” for their habitats and other community members is of increasing importance in seeking wider benefits. Most fundamentally, support will never be sufficient to treat all deserving insect species individually as conservation targets needing expensive long-term recovery actions, and so any constructive shortcuts must be explored.


The International Union for Conservation of Nature (IUCN) has initiated schemes whereby species can be signaled as of conservation concern through being included on a global Red List of Threatened Animals and progressively allocated to a category of threat severity based on quantitative estimates of risk of extinction. The year 2007 Red List includes 623 threatened insect species (of a total of 1255 species evaluated), including representatives of 12 orders, but is dominated by Lepidoptera, Odonata, and, Hymenoptera. Daunting though this number may seem, it is no more than the tip of the iceberg of needy insect taxa. Many of the species included have not been evaluated critically in relation to their close relatives, for example; some are listed as the result of the zeal of individual nominators; and most insect orders have no such champions to promote their welfare. Strong bias is evident in some listings—virtually all listed Hymenoptera, for example are aculeates (mostly ants), and the vast array of parasitoids are absent; most Lepidoptera listed are butterflies, by far less speciose than moths.
A number of regional red data topics dealing with insects have established more local priorities, as have a greater number of Action Plans and similar documents arising from country- or state-based conservation legislations. In common with other taxa, the “listing” of an insect on a schedule of protected taxa often confers legal obligation to define and pursue the necessary conservation measures needed to ensure its well-being. It is important to recognize that simply being “rare” does not necessarily indicate conservation need. Many insects are known from single localities or otherwise very small areas. “Rarity” has connotations of one or more of small numbers, limited distribution, and ecological specialization, with the rarest species being ecological specialists occupying very small areas and occurring in very low numbers. However, rarity can be a stable condition. Conservation concern arises more properly from threats caused by human intervention increasing the level of rarity, such that a risk of extinction is imposed on a formerly stable balance or a trajectory of decline is accelerated. Conditions of rarity may predispose species to stochastic effects and increase their vulnerability if the external threat spectrum increases.
Unlike many conservation assessments for vertebrates, quantitative population data on insects are rarely available, and large numerical fluctuations between successive generations may be entirely normal. Detection of numerical decline is thereby difficult, and must be assessed over multiple generations. The quantitative thresholds for allocating a species to the IUCN categories of “critically endangered,” “endangered,” and “vulnerable” generally cannot be met. For most insects for which any biological information is available, which is a small minority, even the basic pattern of population structure is generally unclear. Many butterfly species previously assumed to have closed populations, for example, are now known to manifest a metapopulation structure, wherein discrete demographic units (nominally subpopula-tions) occur disjunctly in patches of habitat across a wider area, and the whole population is maintained through rolling series of extirpations and recolonizations of the suitable habitat patches in the wider environment. Thus, even loss of whole apparent populations may be entirely normal, and the practical conservation dilemma is to distinguish these from declines and loss caused by imposition of external threats.


The following are the major threats cited in decline and loss of insect species and assemblages.

Habitat Loss and Change

Many insects depend on very intricate and specialized ecological conditions for their survival, so that critical habitat and resource parameters can be very subtle. Whereas destruction of a forest, for example, is an obvious form of habitat loss, relatively small changes in vegetation composition or microclimate may lead to decline of ecologically specialized insects. Many lycaenid butterflies, for example, depend on a tripartite association whereby their caterpillars have obligate mutual-istic relationships with particular species of ants, as well as specific larval food plants, so that both of these are critical resources, in addition to the need for nectar sources for the adult butterflies. On a broader scale, many insects are limited to or associated with particular vegetation types, so that any process that diminishes forests, grasslands, heathlands, alpine meadows, mangroves, and many other habitats may harm them. The area needed for many insect populations to be self-sustaining is not necessarily large—colonies of many butterfly species can thrive on areas of less than a hectare—so that the widespread pattern of habitat fragmentation through agricultural and urban conversion so damaging to many other taxa is not always harmful for insects. But, by the same token, even limited habitat destruction or change might exterminate the entire population or species.
Despite wide supposition to the contrary, many insects do not disperse readily or far. Some butterflies are reluctant to traverse even narrow bands of open ground between sheltered or shaded habitats, so even apparently unobtrusive habitat fragmentation (such as by construction of an access road) may have severe demographic and genetic consequences through promoting isolation.
Habitat loss is the paramount threat concern in insect conservation and is potentially universal. Many insect conservation programs stress the need for habitat security and management as the most important single conservation measure. The latter aspect is critical; simply that an insect is represented in a high-quality reserve such as a National Park does not in itself guarantee its well-being, because conditions may continue to change through succession or management for other priorities. For example, in Britain, several butterflies declined following changed grassland management involving removal of grazing by domestic animals or rabbits. This led to the decline of attendant ant species because of changes in ground microclimates from denser overlying vegetation; particular grazing regimes are an integral part of habitat management for such taxa. Simply “locking up” a habitat in a reserve may be a vital first step in ensuring security, but is not an end point in insect conservation practice.

Invasive Species

Replacement of native flora by exotic plants has characterized much human endeavor. In Australia, native grasslands in the southeast are regarded as among the country’s most endangered ecosystems, having been reduced to around 1% of their original extent. There is still “plenty of grassland,” but most of it is composed of exotic grass species introduced to improve pasture quality for domestic stock. Many insects (including wingless morabine grasshoppers and some Lepidoptera) that depend on native grass species are now of considerable conservation concern, as representing putative remnant populations confined to small patches of their original much wider range. Introduced plants, be they agricultural or forestry crops, weeds or ornamentals, provide opportunity for exotic herbivores to establish and thrive—often as insect pests demanding control in order to protect commercial interests. Classical biological control of introduced pest weeds and arthropods has led to numerous introductions of insect consumers, be they herbivores, predators, or parasitoids. The practice has aroused concern among insect conservationists, because of the propensity of some such taxa to invade natural environments and attack native species, rather than being restricted to the (predominantly) agroecosystem environments where their impacts are needed. Protocols for screening for safety of biological control agents continue to improve, but some recent pest management practices need careful appraisal. Neoclassical biological control (whereby exotic natural enemies are introduced to combat native pest species) is a highly controversial practice, for example, as witness the recent debate over the possible side effects of exotic wasp parasitoids against innocuous native grasshoppers coexisting with the few destructive rangeland species in North America. In such situations, lack of host specificity is a prerequisite, as the agent is required to attack ” new species ” ; the agents are thereby seen as predisposed to become invasive and attack a wider host spectrum. For classical biological control, much concern has arisen from isolated island environments such as Hawaii, where there is strong suggestion that extinctions of sensitive native insects have resulted from nonspecific agents invading natural environments. A tachinid fly, Compsilura concinnata, introduced to combat gypsy moth (an introduced major forest pest in North America), is known to attack a wide variety of native Lepidoptera, with recent concerns for its effects on some giant silk moths (Saturniidae).
Invasive social Hymenoptera, particularly ants such as the Argentine ant, Linepithema humile, and bigheaded ant, Pheidole megacephala, and vespoid wasps (such as Vespula in New Zealand) are known to outcompete native species and to disrupt the structure of natural communities in many parts of the world. As with other invasive taxa, many of these insects are extremely difficult to eradicate once they become established, and continuing spread is a major conservation concern.


Exploitation of insects as a threat revolves largely around issues of “overcollecting,” a highly controversial and emotive theme in insect conservation. Collector demands for rare butterflies and beetles, in particular, have led to the listing of a number of species on schedules of the Convention on International Trade in Endangered Species (CITES) as either prohibited in trade (a few species such as Queen Alexandra’s birdwing butterfly, Ornithoptera alexandrae) or for which numbers in trade must be monitored. Much protective legislation for insects prohibits or restricts take of specimens. Individual rare insects can command sums of many thousands of dollars on the black market or more openly in dealers’ catalogs. Trade in insects is the predominant aspect of exploitation and has three main components (as nominated by Collins and Morris for swallowtail butterflies): The low-value high-volume trade (mainly in common species,for the souvenir trade and general collector supply), the high-value low-volume trade (of very rare species for collectors), and the live trade (mainly of long-lived showy species for display in butterfly houses). The second of these is the major conservation concern, with potential for illicit measures to circumvent protective measures for exceedingly scarce taxa and which has led to development of butterfly farming (or butterfly ranching) activities to help satisfy demand for high-quality reared specimens. This approach was pioneered in Papua New Guinea and has major conservation benefits in helping to reduce human pressures on primary forest habitats. Rearing butterflies for sale through a centralized government-supported agency has provided income sufficient to curtail needs for continued agricultural development in places and has allowed local people to recognize forests as resources on which their sustainable incomes depend.
However, and despite widespread assertion to the contrary, there is very little evidence that overcollecting is a common threat to insect species or populations. It is almost always subsidiary to changes to habitats. Very small, isolated populations of highly desirable species may indeed be “tipped over the brink” by imposition of any additional pressures and mortality, but measures taken to prohibit collection must be seen as a responsible action. They should be balanced against the possible loss of information to be gained from hobbyists, who have contributed most of the information available on collectable insects such as butterflies.

Pesticides and Pollution

Pesticides are a special category of environmental pollutants, in that they are chemicals designed specifically to kill insects, rather than simply the by-product of industrial and other manufacturing processes. Pesticides can have nontarget effects, with the practice of greatest conservation concern being aerial spraying of insects in non-crop environments, either accidentally or purposely. Wiest’s sphinx moth, Euproserpinus wiesti, was almost exterminated when its last known site in Colorado was sprayed with malathion, for example, and aerial use of fenitrothion against massing plague locusts in Australia before they reach cropping areas remains controversial and a stimulus to develop alternative management strategies.
Other forms of chemical contamination, of both land and freshwater environments, have been documented as harmful to insect assemblages, and the more widespread acid rains in the Northern Hemisphere have undoubtedly threatened insects in forest environments. Many local pollutant effects could be cited as occasional threats. Concerns have been expressed widely over effects of insecticides on dispersive pollinators such as honey bees that can forage 5 km or more from their hives.

Climate Change

Climate change poses serious threats for the future of many localized insects, as affecting their distribution and opportunity for dispersal, seasonal development (including diapause regimes) and activity patterns, aspects of growth and reproduction, and synchronization with critical resources such as food plants or prey. Many species of current conservation concern are likely to be affected and, as ecological specialists, may have “nowhere to go” if conditions become unsuitable. Their future well-being necessitates landscape level conservation measures to facilitate habitat connectivity and insect dispersal, rather than relying solely on currently occupied small sites that may become untenable. Most such effects are at present impossible to project in detail, but a growing number of modeling studies are increasing our understanding.


The most familiar forms of insect conservation are associated with campaigns to conserve individual species, often ” crisis-management exercises” stimulated by perception of decline or of current or impending threats from anthropogenic changes to the environment. Many are initially local exercises, but the species may also be of national or (as regional endemics) global concern. Detection and quantification of conservation need are followed, ideally, by well-designed and effectively coordinated management or recovery plans, with adequate monitoring to determine their effectiveness. Sound biological knowledge of the species underlies any such program, and in many programs an initial research phase to elucidate key ecological features must precede optimal management. However, for this to occur, the species may need interim regulatory protection, such as a moratorium on future despoiling of its habitat.
With few exceptions, declines of insects have been difficult to quantify, because of lack of knowledge of population dynamics and absence of historical data on numbers and distribution. Many declines have been inferred from loss of habitat, on the basis of persistence in small remnant habitat patches and presumed losses elsewhere. For some well-known faunas, particularly for butterflies in western Europe, disappearances have been documented more effectively through a century or more of collector intelligence and accumulation of labeled specimens and information. The most complete example is for the British butterflies, a fauna of fewer than 60 resident species for which data are sufficient to plot reliable high-resolution maps of species incidence and change over much of the past century. Such “atlases” have been produced on a 10 X 10 km2 scale and have progressively spawned similar compilations for other insect groups and countries, together with numerous recording schemes to define current situations. In North America, the annual Fourth of July Butterfly Count developed through the Xerces Society (from 1975-1993, now run by the North American Butterfly Association) is an important initiative helping to define the template for insect conservation needs, and has spawned similar enterprises in Canada and Mexico. However, for most of the tropics, which is the most species-rich part of the world for insects, such schemes are impracticable because of the lack of sufficiently informed resident entomologists/hobbyists and the complexity of the faunas, as well as vastly different local priorities.
Most concern for species, then, arises from perceived or anticipated declines to taxa considered rare or threatened in some way. For practical conservation the need is to define the severity of the threat(s), integrating this with knowledge of the species’ ecology, and to determine and pursue the measures needed to alleviate the threat and either (a) prevent decline and/or loss or (b) enable recovery from decline to occur. Development of an Action Plan or Recovery Plan is often accompanied by listing the species on some form of legal or regulatory protection schedule, a step that commonly accords formal obligation to investigate and pursue conservation needs and confers priority over nonlisted species for limited support resources. However, listing has sometimes been seen as an end in itself, considered as conservation rather than as a facilitating mechanism for more practical conservation measures. Many legislations provide for eventual delist-ing of species as secure, and this can come about in either of two ways:
1. More intensive investigation of the species that results from listing it reveals it to be more secure than supposed previously, so that continued categorization as of conservation concern is not warranted.
2. Recovery (or broader management) measures are successful and render the species, and its habitat, secure.
Either outcome is positive, but the process emphasizes the need for periodic review of all listed species to determine changes in security and the effectiveness of conservation measures. The practical steps needed, as for a variety of other taxa, are varied but may include increasing habitat security, intensifying site management (e.g., by enriching it with food plants and eliminating competitive weeds), increasing insect numbers and distribution through ex situ measures such as captive breeding and release, and transloca-tions to sites within the historical range from strong donor colonies. Any such program should be monitored fully and coordinated and managed effectively by a species recovery team whose membership includes informed entomologists. Because of the novelty of insect species management in this way, many such teams still tend to focus on expertise derived from vertebrates rather than reflect invertebrate expertise strongly.
In addition to the “fine grain” conservation level of species focus, assemblages or communities of insects are sometimes adopted as conservation targets, leading to larger scales of consideration.


The high numbers of insect species and higher taxonomic and ecological categories (guilds) comprise a significant proportion of easily sampled biodiversity, with many easily categorized forms, in terrestrial and freshwater environments. They have attracted considerable attention in attempts to document communities and to measure the impacts of changes, whereby aspects of diversity, species composition, and ecological integrity can be evaluated by using insects as highly informative surrogates or indicators in various ways. A burgeoning literature on these topics reflects movements to conserve entities above single species and emphasizes the growing awareness of the key roles of insects in ecosystems and as “signals” of environmental health. Not all insects are amenable to use in this collective way; they are simply too poorly known. The desirable features of insect groups used as indicators include their high diversity and abundance, being widespread within the target ecosystems; being taxonomically tractable and recognizable (not always to species, and genera or families can be used instead of species in some groups, but it is highly desirable that adequate handtopics and identification keys suitable for use by nonspecialists are available); being easily sampled quantitatively or semiquantitatively by simple methods; showing demonstrable changes in response to particular sets of disturbances or otherwise being ecologically responsive; and being sufficiently understood biologically that normal fluctuations in abundance, incidence, and distribution are not confounded with disturbance effects. The best documented insect groups have naturally attracted most attention, and it is sometimes difficult to distinguish the really useful insect groups from those that simply have strong advocates but less proven worth. One constructive approach is to focus on several different taxonomic groups simultaneously and so to incorporate additional ecological breadth.
Another useful approach has been to determine the incidence of “functional groups” among ecologically diverse taxa (such as ants) in which different genera, tribes, or subfamilies coexist but have different trophic habits; respond to different physical, vegeta-tional, or climatic cues; and interact in various ways. Local faunas can thus be characterized in functional terms and changes in balance of the different guilds used to evaluate environmental changes in, often, subtle ways. In freshwater environments, groups such as chironomid flies are diverse and have likewise been used to signal wider effects of pollution or temperature changes. In such contexts, insect indicators are the equivalent of the “miner’s canary,” with the strong implication that their responses may be sufficiently subtle to indicate environmental changes before the effects are reflected in other changes in biota. On a broader scale, the dependence of some insects on particular microclimates may provide a basis to monitor effects of longer term climate change. Thus, in Britain many insects are on the northernmost fringe of a broader European distribution and are confined to south-facing slopes with high insolation. With change in climate, their distribution may well also change; for some, this is already happening.
Insects also have values as flagship or umbrella taxa, much as with some vertebrates in the past. Selected popular insects can capture public sympathy and are of vital importance in spreading advocacy for insect conservation and the broader values of invertebrates. These need not be indicators, but species adopted as local or broader emblems for conservation have been one of the main imperatives in development of insect conservation through bodies such as the Xerces Society (United States) and the former Joint Committee for Conservation of British Insects (United Kingdom, most recently known as Invertebrate Link). Many leading entomological societies now have sections for members interested in conservation and conservation committees to help serve these wider interests. Even more broadly, characterization of community condition in terms of “representativeness” or “typicalness” or the principle of selecting nature reserves on their values as centers of diversity, evolution, or endemism can all benefit from incorporating insects in such evaluations rather than relying on low-diversity, sometimes atypical, vertebrate assessments alone.

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