A Quick History of Entomology

• Prehistory, humans & insects in nature, lore

• Ancient History, first recorded descriptions & uses of insects, Greek, Egyptian, Chinese cultures

• Enlightment Period & Natural History

• Darwin

• Industrial Revolution => Advent of large scale agriculture (especially in USA) & 1st professional entomologists. CV Riley & Biocontrol.

• Elucidation of insect vectored diseases

• Pesticide era

• Post-pesticide era & IPM

• Modern era, beyond traditional IPM

• Future: destabilized Earth era?

• “Pest” is a relative term (Natural vs. Anthropophilic worlds).

• Agriculture is the manipulation of nature to serve the food and fiber demands of humans.

• Agricultural systems are inherently unnatural…

• …because of reduced diversity or altered, non-coadapted components…

•…and therefore tend toward instability.

• Insects, weeds, and plant diseases are the major pest groups.

• Economic and practical goals of pest management frequently do not match.

• This field is ever-changing; climate instability is the newest, most pervasive factor.

Important Concepts aboutAgriculture and Insects

Why insects become pests of plants.Review: Natural World: no “pests”; every species plays a part Anthropogenic World: “pests” in context: damage to food or fiber crops = competition with humans. Some Origins of Plant Pests

• Scale + Economy: massive agricultural operations with low economic injury levels

• Ecological disruption: breakdown of natural controls from pesticides, other agricultural practices, habitat detruction

• Changing crop types: new crops with new pests

• Host plant switching: native insects move from native host plants to agricultural crops

• Exotic pests: insects introduced from elsewhere

• Resistance: resurgence through adaptive response

Integrated Pest Mangement“An approach to the control of pests (insects, diseases, weeds) in which all available techniques are evaluated and integrated into a unified program.” Evans, 1984

Major points:

• More a mind-set than a method or set of particular methods. NOT just an alternative to pesticides; may actually include conditional use of pesticides.• Concept that pests are best managed rather than eradicated.• Concept of stability of whole agro-ecosystem.• Concept of living with the pest as part of a stable system (cf. eradication per se.)• Concepts of ET & EIL as a quantitative guides for triggering control action.• Predictive: requires detailed biological knowledge of pest and environmental factors influencing the system.• Depends on concurrent, accurate pest & environmental monitoring.

Basic Pest Management Decision Theory

EIL:Loss of crop

value

ET: Threshold

(Treatment) level

Buffer zone

Experimentation Monitoring

Some Types of Insect Control Used inPest Management Systyems

Pesticides Traditional toxics Low-residual chemicals Botanical compounds (e.g. rotenone) Biologicals (hormone analogs)

Confusants (pheromones that interrupt mating)

Cultural controls hand-picking (small scale) mulching crop rotation habitat modification

Biological control inundative augmentative

Pesticides (a summary)

• Any substance that can be used to directly reduce populations of a pest. (Pest = weed, fungus, microbe, insect, vertebrate).

• Pesticides have been used for thousands of years.

• There are thousands of types of pesticides and dozens of major categories, based on chemical nature and method of effect.

• Petrochemicals are the base of most modern conventional pesticides.

• Unconventional pesticides, especially as used on insects, include microbes, behavior-changing chemicals, hormone analogs, and other taxon-specific substances.

• In the USA today, a new pesticide must undergo rigorous testing to make sure it works and does not cause unintentional harm to the environment or users. (Such testing is not necessarily adequate.)

• It generally takes many years and millions of dollars to register a new pesticide for field use. Large firms develop and make pesticides; only the most lucrative (not necessarily the most safe or effective) are eventually marketed.

• Most of the most toxic &/or environmentally harmful pesticides are no longer legal to sell or use in the USA. (But some are still made and used in other countries, e.g. DDT)

• Pesticide use, on the farm and in the home, is still very high and represents a major environmental challenge.

• In many instances of pest control, a pesticide is used to guarantee maximum profit margin, i.e. an otherwise harvestable and saleable crop is made more valuable by treating.

• Insects, in particular, have become resistant to many pesticides. This is now a major factor in both managing insects and in developing new pesticides.

Pesticides (continued)

multiple resistance, i.e. instances of resistance

Gullen & Cranston, 2005

Development of pesticide resistance in the USA.

Classical food web exemplifying stability and control of a pest complex through a diverse natural enemy community. Ecological studies of food webs and the particular population dynamics of their components led to the theory and eventual application of biological control.

Potential Pests (primaryconsumers)

Potential SecondaryPests

Natural Enemies (secondaryconsumers)

Biological Control

A component of some IPM systems

General Concept: certain species on higher levels of food web (predators, parasitoids, microbes) used to control plant pests (primary consumers) in agroecosystems.

Assumptions 1) Natural ecosystem of biocontrol agent is equivalent to target agroecosystem 2) Biocontrol agent will respond similarly to surrogate prey/hosts.

Types Natural, native or naturalized elements, background effect “Composed”, natural enemies purposely introduced or augmented to gain desired control effect

Potential Problems with Composed Biocontrol Programs

Ecological mismatch, biocontrol agent non adapted to target system (climate, other predators, parasites, competition, etc.)

Differential response, agent responds differently than anticipated (slow growth, different prey/host)

System initiation, legal/reulatory, time/money constraints, conflicting research results

Backfire! Biocontrol agent may become a pest by attacking other beneficial organisms or by becoming a nuisance, e.g. Multicolored Asian Lady Beetle.

Developing a Biocontrol Program

Research & Development Essential to establishing a working system & protecting environment

Pioneer for biocontrol agents Classical: go to pest country or origin (e.g. Riley) Modern: cooperative efforts, genetic manipulation.

Test in experimental setting with simulated target system, potential alternative prey/hosts. Artificial rearing in large numbers. Economic parameters developed.

Release in real world

Monitor & Modify as system changes

Classical response of biocontrol agent to host.

Historical outcome of biocontrol of weeds.(Weed biocontrol has generally been more successful than biocontrol of insects.)

History of Biological Control

• Historical uses “selected” to succeed

• Some very old success stories have survived, e.g. citrus pest control with ants in China.

• Some early successes in modern agriculture, e.g. Vedalia beetle in citrus.

• Many failures, some disasterous(e.g. Multi-colored Asian Lady Beetle).

• Modern milieu: still useful but proceed with great caution.

C. V. Riley an early professional entomologist.

The Vedalia beetle, Rodolia cardinalis

The Vedalia beetle [& a parasitic fly, Cryptochaetum iceriae (not shown)] introduced from host country (Australia) to control cottony cushion scale on citrus in USA. The first major modern classical biological control success story.

1990’s?

2008

Exotic insect control of an exotic invasive plant. The imported tamarisk beetle,Diorhabda elongata.

Two pest species in WA currently under IPM.

Apple maggot

Gypsy moth

• Monitoring

• Quarantine

• Trapping

• Cultural control

• Chemical control

• Monitoring

• Quarantine

• Microbial control

Control of the Boll WeevilAn Integrated Pest Management

Success Story

Cotton flowers or “squares”

Boll weevil adult, attacking (ovipositing into) a young boll or fruit.

Larva feeding inside the boll.

original detection in U.S.A.,1892

MEXICO,original range

Range expansion of the cotton boll weevil, Antohonomous grandis, (COLEOPTERA: Curculionidae), a native insect turned into a pest by agricultural modification of habitat & food source.

Cotton stubble, refuge habitat for overwintering boll weevil adults.

Fields used to be heavily sprayed during bloom. Butstubble is easily removed by chopping and “plow down”.

Cotton “plow down” program surveilance & compliance.

Boll weevil pheromone monitoring trap.Monitoring is integral to all pest management programs.

Laboratory test of boll weevil parasite. Field release of parasites.

Biological control supplements other procedures.

Epitaph: The boll weevil has become a minor pest; cotton IPM systems have changed to meet the challenges of new pests and new environmental factors.

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