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: