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1 Lecture 1 – Pest Origins, Pesticides & the History of Biocontrol What is a pest? Pest can be defined as any species that interferes with human activities,

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Presentation on theme: "1 Lecture 1 – Pest Origins, Pesticides & the History of Biocontrol What is a pest? Pest can be defined as any species that interferes with human activities,"— Presentation transcript:

1 1 Lecture 1 – Pest Origins, Pesticides & the History of Biocontrol What is a pest? Pest can be defined as any species that interferes with human activities, properties or health

2 2 The need for pest management: Increase population Increase population less land available for agriculture less land available for agriculture Land in agriculture must be very productive Must also be sustainable

3 3 Where do pests come from? Farming practices Increased global trade and movement - pests without N.E. In U.S. the number of insect pest species has increased over 10 times since 1850 Introduced species comprise 39% of the pests on crops, 27% in forests

4 4 Pesticides – Panacea or problem? History: boom began in 1940’s - post WWII boom began in 1940’s - post WWII immediate effects were appealing environmental and effects on natural enemies were less obvious driven by industry and chemical sales “insurance” treatments often ignored need and biology

5 5 Problems with pesticides: temporary temporary expensive often NE’s are more susceptible to pesticides environmental contamination

6 6 Control problems with such heavy reliance on chemicals eventually arose. The first report of resistance to DDT was the house fly in Sweden in 1946 Within 20 years 224 species had developed resistance to one or more groups of insecticides

7 7 Another problem with heavy reliance on pesticides is target pest resurgence. After a spray, the pest drops to very low levels, but then suddenly surges to even higher levels than before the spray WHY? Natural enemies that manage to survive emigrate or starve, and die out. Pests that survive have no NEs and explode

8 8 Third problem is secondary pest outbreak : Occurs when a plant feeding species which is not a pest due to naturally occurring biocontrol suddenly becomes a pest because NEs are destroyed by pesticide. Eg. mites

9 9 We can demonstrate secondary pest outbreaks experimentally: treat blocks of plants with pesticides, leave others as controls PestHost PlantChemical CA red scale citrusDDT purple scaleorangesdieldrin citrus red mitecitrusDDT Pacific mitegrapescarbaryl cyclamen mitestrawberriesparathion cottony-cushion scalecitrusDDT olive scaleolivesDDT

10 10 Reaction to resistance, resurgence and secondary pest outbreak was to increase pesticide use. Resistance to low dose – up the dose Resurgence – spray again and again Secondary pest outbreak – treat like an original pest and add to spray schedule Resulted in more resistance, resurgences and secondary pest outbreaks

11 11 This has been termed “pesticide treadmill” – once on it, grower couldn’t get off Final problem of heavy reliance has been environmental contamination.

12 12 Environmental effects: In high use areas, pesticides may end up in soil, air, water, wildlife etc. Example: hydrochlorinated hydrocarbons (OCs) like DDT bioaccumulate - raptoral birds many have caused human deaths

13 13 History of Biological Control: Intentional manipulation of insects to suppress insects goes back to ancient China in 400 BC gathered, sold and established colonies of predatory weaver ants in citrus orchards to control caterpillars and boring beetles. moved nests around in the orchard and created overhead “ant highways” between trees using bamboo DeBach observed this practice still being used in Burma in the 1950’s

14 14 Parasitoids are less obvious than large predators - first observation was 1602 (Aldrovandi on butterflies - thought they were another life stage) 1st correct interpretation was in 1685, Martin Lister in the Philosophical Transactions of the Royal Society of London described parasitism by Ichneumonid wasps on caterpillars Insect disease - first to experimentally show was Agostino Bassi of Italy with Beauveria on silkworm, 1835

15 15 In Europe, R. Réaumur (in 1734), is thought to be the first to propose biocontrol: he advised the release of lacewings in greenhouses for the control of aphids. 1752 Carl Linneus suggested “every pest has a natural enemy, we should capture and use them to dis-infest crops” In 1840’s predators were released for control of gypsy moth and garden pests in Italy

16 16 North America - rapidly expanding agriculture in 1800’s Wheat midge Sitodiplosis mosellana was known to come from Europe 1855 Asa Fitch N.Y. state entomologist proposed importing parasites from England - didn’t happen

17 17 In 1865, the first successful international importation for weed control took place, when a cochineal insect (Homoptera) was transferred from India (originally from Argentina) to Sri Lanka, where it effectively controlled the prickly pear cactus within a few years

18 18 1873 first international movement of an insect natural enemy - Missouri state entomologist C.V. Riley sent predatory mite Tytoglyphus phylloxera to France for grape phylloxera - establishment but no control 1879 C.V. Riley appointed Chief entomologist for USDA - soon after imported internal parasite of cabbage butterfly. Established, but not very effective agent C. V. Riley - the “Father of modern biological control”

19 19 Cottony Cushion Scale: California Success Cottony Cushion Scale (Icerya purchasi) discovered in Menlo Park 1868 on acacia CA’s new citrus industry was mostly around LA - took 3-4 yrs before it appeared on citrus in LA By 1880 it was throughout CA - almost wiped out the citrus industry Chemical measures (cyanide fumigation) had only limited effect

20 20

21 21 C.V. Riley speculated and confirmed that CCS was from Australia Riley procured funds and sent Albert Koebele to AU in 1888 Keobele found a parasitic fly (Cryptochetum iceryae) and a predacious lady bird beetle (Rodolia cardinalis) [formerly Vedalia]

22 22 Cryptochetum iceryae

23 23 Rodolia cardinalis

24 24 Rodolia cardinalis larvae

25 25 Shipped to SF, reared, then released in tents in LA Beetle quickly established, spread, and provided complete control within 2 years Parasitic fly also became established and is primary control agent in coastal areas

26 26 Saved citrus industry in CA Dramatic success lead to: further federal government support State support through the University of California willingness of public/growers to consider BC Unfortunately CCS project also lead to a great deal of focus on coccinelids for BC in California and Hawaii with little success. By WWII 13 pests controlled in all or part of California.

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