INVERTEBRATE SAMPLING METHODS

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INVERTEBRATE SAMPLING METHODS

• Therese A. Catanach
• Program in Ecology, Evolution, and Conservation
• 1816 South Oak Street, MC 652 Champaign, IL
  61820

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Bugs in a Wildlife Class?

• Invertebrates provide food
• for many wildlife and
• game species
• Perform many
• ecosystem services
• Disease vectors
• Indicators of ecosystem health

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Deciding the Scope of the Question

• What is the scope of your question?
• General questions
• Habitat survey what insects live here?
• Impact of
• management
• Species related
• questions
• Feeding surveys
• Prey availability
• survey

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Invertebrate Natural History

• Invertebrate natural history is important
• Presence does not equal availability
• Size
• Activity level
• Habitat preferences
• Many invertebrates are toxic or mimic those that
  are

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Considerations for Invertebrate Sampling

• Some insects more likely to
• be caught in a certain trap
• than others
• Habitats frequented
• Activity periods
• Attractants used for trapping

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Sweep Nets

• Collect invertebrates in vegetation or flying
• Difficult in thick vegetation or when vegetation
  has thorns/spines
• Can be general or targeted
• Hymenoptera
• Diptera
• Hemiptera
• Lepidoptera
• Orthoptera
• Coleoptera
• Not good for ground dwelling invertebrates

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Malaise Traps

• Passive trap set up along flyways
• Placement
• determines
• catch
• Hymenoptera
• Diptera
• Some Hemiptera
• Some Coleoptera

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Flight Intercept Traps

• Similar to Malaise Traps
• Targets insects that fall rather than climb when
  barriers
• encountered
• Beetles
• Orthoptera

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Pan Traps

• Different colors attract different insects
• Passive Collecting
• Diptera
• Hymenoptera
• Hemiptera

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Sticky Traps

• Standardized trapping effort if placed similarly
• Positioning or damage can make identification
  challenging
• Targets
• Diptera
• Hymenoptera
• Hemiptera
• Coleoptera

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Vacuum Devices

• Ideal for collecting in grasses
• Separate invertebrates from litter using
  emergence traps or by hand
• Targets
• Hemiptera
• Hymenoptera
• Diptera

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Light Traps

• Species must be attracted to light
• Different wavelengths of light attract different
  taxa
• Targets
• Lepidoptera
• Coleoptera
• Hemiptera

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Aquatic Net

• Many methods
• Dragging through sediment
• Disturbing rocks and other shelters
• Targets
• Immatures of many orders
• Aquatic invertebrates

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Beat Sheets

• Ideal for
• vegetation thats
• difficult to sweep
• Coleoptera
• Hemiptera
• Spiders

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Attractant Traps

• Uses attractants (C02, pheromones, fermenting
  fruits, etc.)
• Targets
• Mosquitoes
• Social Insects
• Certain Flies
• Coleoptera
• Ticks

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Other methods

• Watching individuals
• Cameras
• Examining crop/fecal contents
• Stable isotopes

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Proper Curatorial Techniques

• Specimen Handling and Preparation
• Specimen Storage
• Specimen Identification

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Specimen Handling

• Field preservation
• Freezing
• Ethyl Alcohol (70)
• 95 for Molecular work
• Ethyl Acetate
• Ethylene Glycol
• Useful for pitfall and
• similar traps
• Handle specimens carefully
• Even family level ID can require counting hairs
• If breakage occurs, keep pieces with specimen

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Specimen Preparation

• Vouchers should be deposited in a entomological
  collection as a permanent record
• Each collecting event must be labeled
• Location (both written and GPS coordinates),
  date, collecting method, brief habitat
  description, and collector should all be included
  on label

ARGENTINA Jujuy,P.N. Calilegua, Arroyo 3
Cruces, 1110m, 2341.629S6452.070'W 14.i.2008
TACatanach Hg vapor light, grassland TAC2008/040
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Storage

• Insects typically either stored dry, or in ethyl
  alcohol
• If stored dry, low humidity and temperature will
  help with preservation and dermestid beetle
• control
• If in ethyl alcohol
• use 70 and
• check frequently
• for evaporation

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Specimen Identification

• What level of ID is
• necessary to answer
• the question?
• Species level is often
• not feasible
• Be aware that one hour of collecting translates
  into days of lab processing

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SUMMARY

• Invertebrate sampling requires knowledge of
  invertebrate natural history and how it relates
  to the study question or wildlife species of
  interest
• Collecting techniques are varied and often
  specific to habitats and target taxa
• Specimen handling, storage, and identification
  are integral parts of invertebrate sampling and a
  plan for vouchers must be in place