Is it a Family Affair? Kenneth A. Bridle, Ph. D. Director of Stewardship and Inventory Piedmont Land...
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Transcript of Is it a Family Affair? Kenneth A. Bridle, Ph. D. Director of Stewardship and Inventory Piedmont Land...
Is it a Family Affair?
Butterflies and Host Plants
Kenneth A. Bridle, Ph. D.Director of Stewardship and Inventory
Piedmont Land ConservancyAugust 2012
My discomfort with Host Plant ListsMost are over simplificationsEven if lists are correct, Why?
My interest in Plant and Insect InteractionsCo-evolution?
My interest in Natural Product ChemistryChemical ecology and environmental impact
This Presentation
Some Butterflies use many kinds of plants:Painted Lady, Mourning Cloak, Red-spotted
PurpleGray Hairstreak, Spring Azure
Some Plants support many kinds of Butterfly:Willow, Cherry, Nettles, Grasses, Legumes
Some Butterflies and Host Plants are very specificMonarchs, Pine elfin
Butterfly Host Preferences Vary
Monarch Caterpillar
Some evidence suggests that some butterflies can learn the leaf shape/texture
Some insects, including butterflies might be able to see distinctions in leaf color not obvious to usUV light patterns similar to flowers and bees
The best evidence seems to be chemical selection
How Do Butterflies Recognize their Host Plants?
The first insects were polyphagus (Paleozoic) They ate any plant material they found
(sucking sap comes first then chewing later) Most plant matter was similar in composition
Later, some insects specialized in eating spores Plant spores are higher in nutrient value than other tissues
Some spore eaters later moved to pollen with the rise of the angiosperms (Cretaceous) This avoids much toxic chemistry Pollen is hard to digest
Finally some pollen eaters switched to nectar.
Insects with complex life cycles often specialize in different foods at different stages
The history of insects eating plants (greatly abbreviated)
Suppose all insects started out as food generalistsCompetition among plant eaters is high Impact on plants by all the eaters is high
Plants develop some protective chemistry to defend themselvesAn “arms race” starts as insects develop ways to avoid or
metabolically adapt to these new chemistries.
What were once toxic chemistries, soon became markers, attractants and nutritional requirements.
So what started as chemical defense became the basis of mutual adaptation.
Evolution from Polyphagus to Oligophagus to Monophagus
Geologic Time
Repellants / Attractants Change movement direction of insects
Start or Stop Movement Simulant or depressant of locomotors systems May work in-vitro
Start or Stop Feeding
Antibiotics Limit larval growth and development Limit life expectancy/ fecundity of Adults
Ovipositional cues
Plant Chemicals influence Insects in many ways
Cloudless Sulfur laying eggs
Basic Biological ChemistryCarbohydrates, Proteins, Nucleic Acids
Plant Structural ChemistryCellulose , Lignin, Tannin
Plant Secondary Natural ProductsNot strictly necessary for growth and development
Internal toxic compoundsVolatile organics that surround the plantLeaf Surface Chemistry
Induced or Constitutive Induced are made in response to damage
Types of Plant Chemistry
Plant Natural Product Chemistry
Compounds found on the leaf Surface
Plant Leaf Cross Section
Leaf under Dissecting Microscope
Monarch Egg
Glandular Trichomes under Electron Microscope
Trichome Exudate collected on Glass
Large Scale Leaf Surface Chemistry Collection
Gas Chromatograph of Leaf Surface Chemistry, Nightshade and Tomato
Chromatograph of Flue Cured Tobacco
Chromatograph of Oriental Tobacco
Tobacco Bud Worm Moth
Plant Sterols
Closely related plants share growth habit, structural and biochemical themesThey look (and smell) alike to us and insects
Chemistries that have adaptive advantage are continued from ancestral types of plantsIf it works stick with it
Members of plant families usually have variations on the basic chemical theme(s)Tweaking and improving all the time
Plant Chemistry is a Family Trait
Common Plant Families
Started with the list of common plant families, identify the ones known to be used by butterflies35 families host butterflies out of about 150 in
floraAbout 17 plant families host the majority of
butterflies
Made a table of these most common host plants compared to the families of butterflies
XX means many butterflies in that group
What are the important butterfly host plant families in our area?
SwallowtailsTigers, Pipevines, Blacks, Zebra
Blues and HairstreaksAzures, Eastern-tailed Blue
BrushfootsMonarch, Fritillaries, Buckeye, Satyr, Wood
nymphYellows and Whites
Cabbage White, Sleepy Orange, SulfursSkippers
Fiery, Silver Spotted, Sachem
Butterfly Family Groups
The Family Correlation
At the Family level there appears to be a segregation of butterfly families using plant familiesNo one plant family is used by all butterflies
Three plant families are used by three butterfly families
Three plant families are used by two butterfly families
Eleven plant families are used by only one butterfly family
Many families are not butterfly hosts, but may be hosts of other insects.
Thoughts on Family Correlation
The Whites and Yellows group nicely in two familiesYellows use legumes, Whites use brassicas
Skippers group into three plant familiesThese are most often found in open fields and
grassland natural communities.The Swallowtails and Brushfoots seem to
diversify mostSwallowtails predominantly on woody speciesBrushfoots seem to favor herbaceous
If the Gossamers, Yellows and Whites and Skippers were broken into subfamilies other patterns might appear
This is by no means a rigorous scientific study, there is lots of room for improvement.
Subsequent to the original presentation, “Butterflies of the East Coast an Observers Guide” was published (Cech and Tudor, 2005)
These authors recognize the importance of plant families to the butterfly host plant discussion in several parts of this book.
They also integrate host plant use with theories of butterfly lifestyle or success strategies
Additional Information
Cech and Tudor 2005
Host-Plant Related Lifestyles
Cech and Tudor 2005
Host plant selection and use is complex and is certainly varies depending on the species involved
Ovipositional cues are most likely chemical although some visual cues and random trial also occur
Chemical content of the leaf both feeds larva and may protect larva and later adults from predation and completion. These insects are often harmed or suppressed, but they are still successful.
Relationships of host plants and insect predators reflect past evolution and speciation. Plant chemical arms race might be responsible for insect diversity explosion in
Cretaceous
Diversity of plant families in an area probably supports a diversity of butterfly species Good for wildlife sensitive gardeners to know
Awareness of chemical cues in nature will make us better naturalists.
Final thoughts
Dennis BurnetteFounder of the Carolina Butterfly SocietyMotivational force behind the Triad ChapterAnd special thanks for any butterfly images
which may have slipped into any of my butterfly presentations!
To all the folks who organize and report butterfly counts. This is really great citizen science.
To the current board of CBS and organizers of this meeting.
Thanks to: