Lecture 23: Trade and pests

Key Points:Trade and pests

• ID the below three species– CPB– SWD– BMSB

• What is the underlying reason why problems like CPB develops

• Which of these three abovementioned species switched hosts

• Which species affects small fruit• Which species affects fruit, veg and nurseries

• CPB: A serious pest of potatoes– now cosmopolitan– with a fascinating history

Handsome devil, ‘eh?

Voyage of the Beetle

• 17th century & the Spanish Conquista

• Living in central Mexico was a beetle which fed on burweeds (Solanum

rostratum)

It’s name was Leptinotarsa decemlineata

• Burweed– also known as Buffalo Bur &/or Kansas

Thistle– Native of Meso-America (NOT North

America)– Primary host plant for L. decemlineata

L. decemlineata• Life History

– wet season & female cements her eggs to bur weed leaves - batches of ca. 20 eggs

L. decemlineata• Adults are brightly colored

– warning coloration– “mess with me & I’ll toss my cookies”

• Larval beetle is brightly colored

L. decemlineata• Both adult and larval beetles are

defoliators

L. decemlineata

Step Number One

Necessary to get this

L. decemlineata

• Note:– In the 17th century the potato was NOT

found in North America or Mexico.– In the 17th century L. decemlineata was

NOT a pest insect for the indigenous peoples of Meso America.

Voyage of the Beetle

• Spanish introduced cattle to the “New” world

• “Vaca” driven to northern markets in Texas in late 17th

& early 18th centuries.• The cows carried the spiny

seeds of the burweed, and the plant began a northward migration.

• Bison also picked up the burweed seeds and carried them even further north.

Voyage of the Beetle

• As the host burweed plant moved north, so followed the beetle.

• The beetles followed the northward trail of their host plant and by 1820 had reached the Great Plains of America.

• It was here that the beetle was discovered by the entomologist Thomas Say and named.

The potato• Native to the western

highlands of South America• Solanum tuberosum

– a.k.a. the IRISH potato

“Discovered” by Franciso Pizarro in 1531 during his “rape” of the Inca empire.

The potatoPopular Elizabethan English legend has it that the potato was brought to England about 1580 by either

Sir Francis Drake, or Sir Walter Raleigh, or Both!!

The potato

• 1719– potato seed stock sent from Ireland

back to the “New” World (New Hampshire, actually).

• Potato culture (growing) spread quickly throughout America

• Hypothesized that L. decemlineata first encountered potatoes ca. 1820

The potato & the beetle• 1859

–CPB made the transition from burweed to potato in central plains of U.S.

–CPB population EXPLODED–Described in terms of biblical

plagues, especially along the northeastern U.S. seaboard potato growing regions.

The potato & the beetle

1875–CPB crosses the

Atlantic to England {a small gift to

our cousins}–during the next 100

years they spread throughout Europe.

The potato & the beetle• 1900

– W.L. Tower shows that CPB originated in Mexico, NOT Colorado or Iowa as many believed.

– Mexican CPB populations have yellow larvae that do not eat potatoes

– American CPB populations have red larvae that love to eat potatoes

– Tower believed the CPB of the U.S. was a new “variety”/subspecies.

The potato & the beetle• 1982

–T.H. Hsiao (geneticist at Utah State Univ.)

–Found a chromosomal inversion in the potato eating variety of the CPB

–Potato eating gene (allele) found to be dominant & explained the feed switch which elevated the beetle into major pest status.

Very minor genetic differences have enabled the beetle to switch plant hosts. {And} the beetle populations that have followed have had a major impact on our agriculture and history. Lu & Lazell - 1996

Final Thoughts

CPB Control• Huge list of chemical materials.• Some novelties:

– Transgenic potatoes that have had B.t. genes incorporated so that the plant produces B.t. toxins.

– Sounds good!! But what are some problems??• Resistance• use as human food

Spotted Wing Vinegar Flya.k.a Cherry Vinegar Fly

Drosophila suzukii

The “Newest” Plague to the PNW

Drosophila diversity

Female flies about tooviposite on a rasp-berry fruit.

D. suzukii

Hosts

Infested blueberry{with oviposition holes}

Fly larvae exiting blueberry

Spotted Wing Drosophila  

D. Dalton

D. suzukii biography• First “discovered” in Japan {1916}• Pest throughout Asia• First seen in U.S. in the autumn of 2008

{California}• First seen in PNW in 2009

– Blueberries & Raspberries = 20% loss– California cherry industry = 30% loss

SWD U.S. Distribution 2010

D. suzukii biology• Thrives in cooler climates {read that as

the Willamette Valley}• Up to ten generations per year• Short life cycle (egg to adult) = as little

as ten days• Multiple fruit hosts available in western

fruit growing regions of the PNW.

The future: Brown Marmorated Stink Bug

This bug has a wide host range, potentially causing even more economic damage than SWD

Key Points:Trade and pests

• ID the below three species– CPB– SWD– BMSB

• What is the underlying reason why problems like CPB develops

• Which of these three abovementioned species switched hosts

• Which species affects small fruit• Which species affects fruit, veg and nurseries