Basics of Insect Ecology & Metamorphosis
Basics of Insect Ecology & Metamorphosis
Week 3: 18 September
Table of Contents
Ecology and related definitions
Incomplete vs. complete Metamorphosis
Sorting, pinning, labeling
Note: Learn what’s IN RED!!!
Incomplete vs. Complete Metamorphosis
Definition: Insect life cycles.
Types of Metamorphosis:
Incomplete (Gradual) Metamorphosis: Also known as Hemimetabolous.
Life Cycle:
Egg
Nymph (multiple molts)
Adult
Complete Metamorphosis: Also known as Holometabolous.
Life Cycle:
Egg
Larva
Pupa
Adult
Gradual Metamorphosis
Example: Life Cycle of the Insidious Flower Bug
Stages:
Egg
Nymphal stages
Adult
Type 1 (Paurometabolous):
Nymphs look like smaller, less-developed versions of adults.
Nymphs inhabit the same habitat as adults.
Type 2:
Nymphs look different from adults.
Nymphs live in different habitats.
Example Species: Hesperoperla pacifica.
Images Provided:
Adult Hesperoperla pacifica
Larva Hesperoperla pacifica
Typical adult and larval stonefly patterns.
Complete Metamorphosis
Stages of Life Cycle:
Egg
Larva
Pupa
Adult
Development Types:
Hemimetabolous Development: Pronymph -> Nymph (Instar 1) -> Nymph (Instar 2)
Holometabolous Development: Larva (Instar 1) -> Larva (Instar 2) -> Pupa -> Adult
New Definitions
Molt: The process of shedding the exoskeleton due to body growth.
Instar: The developmental stage of an insect between successive molts; the first instar is between hatching and the first molt.
Oviposit: The act of laying eggs; an ovipositor is used by females to lay eggs.
Cerci: A pair of appendages located at the posterior end of the abdomen.
Parthenogenesis: The development of an egg without fertilization.
Definitions Continued
Nymph: The juvenile stages of insects that undergo incomplete metamorphosis.
Naiad: A type of aquatic, gill-breathing nymph.
Larva (pl. larvae): The juvenile stages of insects with complete metamorphosis before they become pupae.
Pupa (pl. pupae): The stage between larva and adult in insects with complete metamorphosis; a stage that is non-feeding and usually inactive.
Ecology Overview
Ecology: The scientific study of the interactions between organisms and their environment, which includes both physical environments and other organisms.
Habitat: The environment where an organism normally lives.
Ecosystem: The community of organisms in a particular habitat along with their physical environment.
Sub-disciplines of Ecology
Behavioral Ecology: Study of the ecological and evolutionary basis of animal behavior.
Sexual Selection: A type of natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.
Population Ecology: Study of how populations of species interact with their environment and the dynamics that regulate their size.
Community Ecology: Study of interactions between species in communities.
Landscape Ecology: Study of the relationships between ecological processes and spatial patterns in landscapes.
Vector Ecology: Investigation of vectors that transmit pathogens.
Interactions in Ecology
Interspecific Competition: Competition between individuals of different species.
Intraspecific Competition: Competition between individuals of the same species.
Types of Interactions:
Competition
Predation/Prey
Parasitism
Territoriality
Social Systems
Definitions Continued
Ecological Niche: The ecological role and space that an organism fills in an ecosystem.
Life History: The complete series of changes in a life cycle including birth, growth to maturity, reproduction, and death.
Biogeography: The geographical area where a species currently exists and the study of the distribution of organisms.
Diversity (Species Diversity ≈ Richness): The number of species present in a given area or group.
Food Chain and Food Web
Food Chain: Represents a linear series of energy flow through trophic levels (primary producers to primary consumers to secondary consumers, etc.).
Food Web: A complex network of feeding relationships among organisms in an ecosystem.
Example: Includes species like hawks, owls, foxes, snakes, rabbits, squirrels, mice, toads, spiders, and various insectivorous and herbivorous insects.
Visualization of Food Webs
3D Visualization:
Species in dark shades represent free-living species, while light shades represent parasites.
Connections/links in the web through consumption.
Basal trophic levels are at the bottom, upper trophic levels on top.
Reference: Figure showing the complexity of real food webs including parasites from the Carpinteria Salt Marsh.
Trophic Pyramid
Illustrates the levels of consumers and producers in an ecosystem:
Primary Producers
Primary Consumers (Herbivores)
Secondary Consumers (Carnivores)
Tertiary Consumers (Predators)
Decomposers handle breakdown of organic material.
Other Potential Niches
Examples include:
Pollinators
Parasites
Detritivores
Seed Dispersers
Pathogen Vectors
Burrowers
Cavity Nesters
Example: West Nile Virus Transmission Cycle
Indicates the role of vectors like mosquitoes and hosts like birds.
Ecological Niche
Concept that even species with similar habitats will exhibit niche differentiation to alleviate competition.
Example species: Flamingos, dabbling ducks, avocets, oystercatchers, and plovers displaying diverse feeding methods.
Life History
Incorporates changes from larva with developing structures to adult forms across species, demonstrating progression through life stages.
Case Study: Life History of Livestock Liver Fluke
Stages:
Egg -> Cercaria -> Metacercaria in ants -> Cow ingests infected ant -> Adult in bile duct of liver.
Biogeography
Focus: Current and historical ranges of species such as the American burying beetle.
Maps demonstrate geographical distributions and environmental adaptations.
Species Diversity: Current estimates of insect diversity and total species count:
Total Known Species: 1,413,000
Insect Species: 751,000
Other Groups included with their species counts (Fungi, Algae, Other Animals, etc.).
Dispersal and Migration
Techniques for improving survival and reproductive success in changing environments tied to natural selection principles.
Natural Selection
Defined as genetic variations among individuals affecting their survival and reproduction. Traits enhancing successful reproduction are more likely to be inherited.
Future generations exhibit evolutionary change; illustrated through a hypothetical example of beetle color selection.
Practical Activities: Sorting, Pinning, Labeling
Emphasis on correct methods for entomological specimen preservation.
Insects need to be pinned correctly to maintain specific information such as locality, date collected, and collector’s identity.
Final Guidance on Labeling
Labels Must Include:
LOCATION (state, county, town)
DATE collected (day-month-year format)
COLLECTOR’s name
Other relevant information (if applicable).
Example of a Proper Label
Location: RI Providence Co, Johnston
Date: 27-SEPT-2012
Collector: Aliberti Lubertazzi MA, Snake Den SP, under log
Etiquette for Bug Collecting
Collection Methods:
Use of alcohol for tiny or soft-bodied specimens.
Use of “Death Jar” or freeze methods for larger specimens with harder bodies, excluding caterpillars.
Importance of returning environments to their original state after collection activities.
Field Practice and Mapping
Emphasis on walking routes, identification of collection sites, and documentation through coordinates in habitat areas.
Maps and Logistics Information
References to local environments, routing, and geographical identifiers for effective bug collecting expeditions.
Concluding Remarks
Ecology and Biology: Encourage understanding of ecological systems, species diversity, and responsible fieldwork practices as essential components of ecological studies.