Ecology and Conservation of Invertebrates

• Unique aspects of the ecology of invertebrates

• Issues in the conservation of invertebrates

Invertebrate Ecology

• Predominance of complex lifecycles where juvenile forms differ morphologically and ecologically from adult forms

• Presence of eruptive dynamics

• Role in decomposition

• Role as parasites

Consequences of complex life cycles in Invertebrates

• Processes affecting dynamics of juveniles may differ and be unrelated to those affecting dynamics of adult populations

• Juveniles and adult do not compete for the same food resources

• Juvenile and adult forms may be specialized for a limited set of functions, such a feeding, dispersal, and/or reproduction

• Most species tend to be highly fecund, but juvenile survival rates are low

Eruptive Dynamics

African Plague Locust – Schisotcerca gregaria

Locust Plagues(Insecta: Orthoptera)

March 2004

Cameraria hamdryadella

Dynamics of Cameraria hamadryadella(Lepidoptera: Gracillariidae)

year

1983 1987 1991 1995 1999

mines per leaf

0.001

0.01

0.1

1

10

100

1000

Oak GroveSW Woodland

year

1983 1987 1991 1995 1999

B. Second GenerationA. First Generation

Invertebrate Parasites

• Platyhelminthes (flukes and tapeworms)

• Nematoda (roundworms)

• Arthropoda (lice, ticks, botflies, blowflies, etc.)

• Nematomorpha (horse hair worms)

Role of Invertebrates in Decomposition

• The decomposition of dead plant, animal tissues, and fecal matter is accelerated by the activity of invertebrates

• By physically assisting in the break-up of plant and animal tissues, increasing surface area for bacterial and fungal activity

• By ingestion and digestion of plant and animal tissues or feces

• Widespread in marine, freshwater, and terrestrial environments involving members of most phyla

Why Conserve Invertebrates?

• Speciesist arguments that they have a right to existence

• Aesthetically pleasing

• Legally mandated

• Provide valuable Ecosystem Services

• Are a resource for human use (food, biochemicals, jewelery, etc.)

Right to Existence

• Some ethicists argue that not only individuals, but also species have a right to existence

• Other ethicists claim that all rights are vested in individuals, not in larger aggregate entities like species or other taxonomic categories

Aesthetically Pleasing

• Most humans find butterflies and some other invertebrates aesthetically pleasing (scarab beetles, corals, anything else?)

• However, most invertebrate groups do not have the charismatic appeal of birds and mammals

• Most humans see invertebrates more as vermin and as threats than as attractive and worthy of conservation efforts

Legally Mandated

• Endangered Species Act or USA and California

• International Prohibitions on Trade and Transport

Ecosystem Services

Ecosystem services are the essential functions of ecosystems that are carried out via the activities of plant or animal groups.

For example, plants function as primary producers fixing carbon and energy using CO2 and sunlight.

Ecosystem Services provided by Invertebrates

• Pollination

• Seed dispersal

• Natural enemies of other pests

• Decomposition

• Soil formation

Invertebrates as a Resource

• Source of food for humans• Bait for fishing• Sponges for bathing • Corals, Conchs, Oysters and others for jewelry• Cloth production (silk)• Bees as pollinators of crops• Wasps, beetles, mantids, spiders, for biocontrol• Medicinal use of leeches• Target of bio-prospecting

Invertebrates as Food

• Mollusca (squid, mussels, clams, oysters, scallops, snails, abalone)

• Crustacea (shrimp, lobsters, crabs, spider crabs)• Insecta (beetles, ants, termites, grasshoppers,

bees)• Echinodermata (sea cucumbers, sea urchins)• Cnidaria (jellyfish) • Annelida (palolo worms)

Bait for Fishing

• Earthworms (Oligochaeta)

• Insect larvae (Neuroptera – night crawlers)

• Shrimp, etc.

Sponges

• Collecting and use of about 12 species of sponges continues since they are considered of higher quality than synthetic sponges

Invertebrate used in Jewelry

• Morpho butterflies

• Scarab beetles

• Rare corals

• Oysters and Conchs for pearl and mother of pearl

Silk production

• Silk moth Bombyx mori

Commercial Pollination Services

• Honey bees are mass produced and transported to farms during flowering periods to insure adequate pollination of crop plants

• Without pollination fruits and vegetables from insect pollinated crops will not be produced

Biological Control Agents

• Insects and other invertebrates are being used in biological control

• In agriculture, inundative release of invertebrate predators or parasites are used to suppress crop pests

• In forestry and range management, classical biological control used to suppress pest weeds

Medicinal use of Leeches

• Medicinal leeches are still used to reduce bruising and scarring after surgery

Target of Bio-prospecting

• Invertebrates could serve as a source of biochemicals useful in medicine and other applications

Pharmacologically active Compounds from Invertebrates

• Ecteinascidin – from tunicates – tested for treatment of breast and ovarian cancers

• Topsentin – from sponges – anti-inflammatory

• Lasonolide – from sponge (Forcepia sp). – anti-tumor

• Discodermalide – from sponges (Discomermia) – anti-tumor Bryostatin – from Bryozoan (Bugula neritina) – anti cancer

• Pseudopterosins – from octocoral (Pseudoterogorgia elisabethae) – anti-infammatory and analgesic agents that reduce swelling and skin irritation

• Omega Conotoxin MVIIA – extracted from cone snails (Conus magnus) – potent pain killer

Threats to Invertebrate Conservation

• Consumption• By catch• Habitat destruction• Pollution• Introduced species

• Habitat destruction• Introduced species• Pollution• Consumption

Aquatic Environments Terrestrial Environments

Ornithoptera alexandrae

Male Female (wing span 30 cm )

Collecting and habitat destruction for Oil Palm plantations in PNG

Maculinea arion• Declined from over 100,000

individuals between 1952-1972

• Went extinct in England 1979 even in nature preserves design for its protection

• Feeds on flowers of Thymus in early larval stages

• Commensal in the nests of an ant, Myrmica sabuleti, in later larval stages

• Reduction in sheep and rabbit grazing altered microclimate near ground and M. sabultei was replaced by M. scabrinodes

• M. scabrinodes not a adequate host for M. arion

• Now successfully re-established after modifying grazing regime

Maculinea arion

Wetas – Deinacrida sp. (Insecta: Orthoptera)

• Large ground dwelling cricket-like insects in New Zealand

• Many species only persist on small islands where introduced predators (rats, mice, and cats) are absent

• Persistence of mainland populations requires establishment of predator free reserves

• Habitat destruction also contributed to declines

Hemideina thoracica

Auckland Tree Weta

Photo by John Wattie

Distribution of Giant Wetas in New Zealand

Medicinal Leech – Hirudo medicinalis

• Used for blood letting since the 5th century BC• Still used to reduce bruising and scarring after

surgery and contains important anti-coagulant compounds

• Intense collecting and habitat loss in Europe where it is native led to severe decline and its listing as threatened by the IUCN

• Captive breeding now being used in place of wild caught animals

Noble Crayfish

Astacus astacus – noble crayfish (Crustacea) – IUCN endangered

• Formerly abundant European Crayfish

• Pollution (DDT and lake acidification)

• Fungal disease introduced from North America

• Competition with introduced crayfish

• Size based catch limitation and attempts to stop disease spread

Extinct Insects in the Bay Area

• First recorded extinction of a native US insect Satyr butterfly (Cercyonis sthenele sthenele (19th century)

• Pheres Blue butterfly (Icaricia icaroides pheres) and Xerces blue (Glaucopsyche xerces) extinct in 20th century

• Antioch dune shield back katydid (Neduba extincta), extinct before it was described from a single museum specimen

Endangered Insects in the Bay Area

Lepidoptera Lange’s metalmark Apodemia mormo langei

San Bruno elfin Incisalia mossii bayensis

Behren’s silverspot Speyeria zene behrensii

Mission blue Icaricia incaroides missionensis

Callippe silverspot Speyeria callippe callippe

Myrtle’s silverspot Speyeria zene myrtleae

Bay checkerspot Euphydryas editha bayensis

Coleoptera Delta green beetle Elaphrus viridis

Insect Conservation in the Bay Area

• Hard to know what species were here before extensive human settlement

• Of the pinned insect collection in the CAS, 248,565 specimens represent 8,668 species and sub-species

• West Germany has 9,694 species and is 13.9 times larger than the 9 county region

• CAS estimate an underestimate

• Recent sampling of bees in Napa and Sonoma counties recorded 17 and 10 species respectively, that are not in the CAS collection

San Francisco butterflies and insects

• 46 species of butterflies native to San Francisco• Only 26 species have been observed in the last 15 years• 3 species are known to be extinct, but the other species

occur in other counties• Given that only 14% of the land area of San Francisco is in

parks, we would predict using the species-area relationship that 18 species should have been lost from San Francisco, but about 20 have been

• So about 6.5% of the insects native to San Francisco are possibly extinct and 43% are no longer found in there , but persist in adjacent counties

Introduced Species - Snails

• Giant African snail Achatina fulica – dispersed by people for food, but became a crop pest

• Euglandina rosea was introduced on various Pacific islands to control Achatina

• Euglandina has caused the extinction of native snails on Morrea in the genus Partula, and has been sown to prey on aquatic species as well

Giant African Snail

Euglandina rosea

Introduced Invertebrates in California

• 177 species of insects invaded California between 1955 and 1988 (5 species/year)

• Over 200 species of invertebrates have invaded San Francisco Bay and in some areas of the Bay account for 95% of the biomass

Summary

• Ecology of invertebrates highly diverse

• Growing number of invertebrate species are endangered or threatened by human activities

• Invertebrates are valuable resources for humans, but our ignorance of their biology and distribution hamper conservation