lecture 23: trade and pests. key points: trade and pests id the below three species –cpb –swd...
TRANSCRIPT
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
• 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 potato
Popular 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
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
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