What is Biological Control and Why is it Needed?

--Get student views and background

--What do you know now about biological control?

--What do you hope to learn? Read chs 1 and 2 of text Goals of Biological Control

• Global invader suppression: Lower density of invasive pest in the whole landscape, permanently

• Help farmers: Keep pest density in crops below injury levels, for one or more seasons

Target Groups

Usual targets • (whiteflies, aphids, mealybugs, ) • Mites (2-spotted spider mite-via augmentation) • Plants (waterhyacinth, Salvinia, thistles, spurge)

Rarely targets, but has been done • Other invertebrates (snails, millipedes) • Vertebrates (rabbits, cats) Types of Natural Enemies

• • Predators • Pathogens (of both in insects, weeds, vertebrates) • Specialized herbivores Techniques of Biological Control

Area wide, Field level Against insects permanent control or weeds control Classical biocontrol XX XX I, W

Habitat manipulation XX I

Pathogens as pesticides XX I (W)

Insectary releases XX I

Reasons BC is Needed

1. Invasions of new exotic pests

2. Problems with pesticides

Invasions of new exotic pests INSPECTIONS TO SLOW RATE OF PEST INVASION Invasions of new exotic pests INCREASING LOAD OF INVASIVE PEST INSECTS Invasions of new exotic pests OVER HALF OF INVASIVE INSECTS BECOME PESTS Problems with pesticides MANY PESTS ARE RESISTANT TO PESTICIDES A history of the development of resistance to pesticides by Colorado potato on Long Island, New York lead arsenate cryolite flood cryolite

pyrethrum pyrethrum sabadilla flood sabadilla lead arsenate nicotine sulphate/fish oil

Before 1945, pesticides were based on minerals (e.g., lead, cryolite, arsenic) and plant extracts (e.g., pyrethrum, sabadilla, nicotine, etc) DDT dichloro-diphenyl-trichloroethane

Paul Hermann Müller (1899 - 1965)

In 1939, the insecticidal properties of a synthetic chemical,

DDT, were discovered. The large scale use of DDT to delouse soldiers and civilians in WWII spurred the creation of an industry for chemical (rather than botanical) pesticides.

flood DDT DDT DDT flood DDT flood

flood DDT became DDT DDT widely used Lead arsenate for most pests DDT DDT flood Lead arsenate The 1950s and 1960s were the era of chemical pest control

This control system 1. Was based on rapid development of many new pesticides 2. Employed pesticides as the sole method of control 3. Used preventative and calendar based applications 4. Treated at the first sign of pests in crop, regardless of number 5. Did not monitor to learn current pest density 6. Was inexpensive and effective but polluting and not sustainable

Problems with pesticides USE OF PESTICIDES IN MAJOR CROPS Reasons for the End of the Chemical Pest Control Era

1. Pest control failures due to pesticide resistance

2. Pest outbreaks due to resurgence

3. Pest outbreaks due to secondary pests

4. Environmental contamination with residues Pest Resurgence

Natural Enemy (3) www.uky.edu/Classes/ENT/530/Lecture_Notes/ mar29/mar29.ppt

Pesticide is applied Pest = 2 Natural Enemy = 0

Pest = 7 Natural Enemy = 3

Pest = 14 Problems with pesticides: Pest control failures due to the destruction of natural enemies (pest resurgence or secondary pest outbreaks)

DeBach demonstrated resurgence by using DDT to eliminate Aphytis melinus from citrus groves. Red scale populations exploded

Pesticide applied to kill target pest Secondary Pest Outbreak

Target pest

natural enemy of secondary pest secondary pest In the absence of its natural enemies, the “secondary pest” rapidly increases in density Outbreaks of two spotted spider mites are routinely caused when pesticides applied for other pests kill most of the phytoseiid predator mites that normally control spider mites Pesticides also damaged the environment Influential book sounding alarm over pesticide abuse Pesticides in food chains

Bioaccumulation refers to the concentration in a food chain of a fat soluble material such as DDT or PCB. This lead to loss of eagle and falcon populations in wide areas Thin-egg-shell syndrome in raptors, pelicans and other wading birds Illness in farmworkers exposed to fresh pesticide residues use new pesticide Pesticide Treadmill resistance

use more pesticide START: chronic Pest outbreaks Problem

use more use resurgence & pesticide pesticide replacement www.agls.uidaho.edu/hort_disease/ Lectures/Lecture02_IPM.ppt Shift to IPM

Critical paper: Stern, In the 1960s, Smith, Hagen and pesticide use van den Bosch,1959 “The Integrated dominated pest Control Concept” management. Critical Project: IPM was invented control of the spotted as process to aphid reinsert natural enemies into the control system Robert van den Bosch was an outspoken critic of pesticide misuse To monitor mites in apples, for example, one has to count the mites on samples of leaves, frequently (1 or 2 times per week)

Counting mites Traps can be used to track relative abundance of pests in crops

White traps for apple sawflies

Red ball traps for Yellow traps for whiteflies apple maggot

Pest injury levels indicate what density of pests really cause losses

Economic spray SPRAY

Injury Level

Economic Threshold

with

InfestationLevel control DO NOT SPRAY NOT DO May June July August Deformed frogs:

An unsolved problem

Caused by herbicides?

Looking back: how did use of biological control get started?

Before use came knowledge, beginning with understanding of the existence and biology of natural enemies. Predators parasitioids were obvious, but parasitoids and pathogens were first understood in the 18th and 19th centuries, in Europe

1662 WOODCUT IN EUROPE

#1. Precedent for classical biological control: Vedalia beetle, in CA, controlled cottony cushion scale and saved an young but important industry To import predators into CA from the native range of cottony cushion scale (Australia) required long ship journeys, which required rearing the insects through several generations on board OVER HALF OF INVASIVE INSECTS BECOME PESTS also was an important but less visible natural enemy of cottony cushion scale Data showing control of CCS in Australia on caged and uncaged plants- caging raises scale survival from 5 to 50% (Prasad 1989)

Data showing that source of control of CCS in Australia varies by season, with Rodolia being the key agent in warm periods and the during cooler months (Prasad 1989)

Making a Science out of It

1. 1913-hired to give direction to BC efforts of Hort. Comm., which were drifting 2. Began to place use of BC on scientific basis 3. Healed rift with USDA allowing CA to continue to import natural enemies 4. Served as head of BC efforts from 1913 to 1951 5. Oversaw movement of BC programs from state to University in 1923 6. Trained first graduate students in biological control Paul DeBach career: 1945-1983

1. Wrote 1964 basic text for science 2. Solved the red scale problem 3. Developed methods to evaluation natural enemy impacts

Paul DeBach Control of a GWSS, Plant Disease Vector

Mark Hoddle Glassy wing sharpshooter

Mark Hoddle and other worked to control glassy wing sharp shooter, a threat to the wine industry. Control has been achieved in CA, Tahiti, and other islands More precedent projects #2. Precedent for classical biological weed control: Introduced moth controlled Opuntia cactus in Australia Infestation in Australia in the 1920s before natural enemy release Of 50 species considered, one (Cactoblastis cactorum) was dramatically successful in reducing cactus density After natural enemy release----collapsing, dying stands of cactus OVER HALF OF INVASIVE INSECTS After death of cacti, land BECOME PESTSbecame economically valuable for crops again #3. First classical weed biological success in the US : St. Johnswort infestation in CA in 1940s, dominating grasslands

Yellow is dense infestation of weed Two species of Chrysolina (Chrysomelidae) controlled the weed in the western US in the 1950s and 1960s Same release site after insects suppressed the weed: a return to native and economically valuable vegetation #4. Precedent for CBC of an insect using a pathogen : Control of the palm pest, rhinoceros beetle, in the South Pacific with an introduced baculovirus

On Pacific islands, coconut palms are a basic crop.

Rhinoceros beetle larvae feed in and destroy palms

An Oryctes virus was found in the pest in Malaysia and introduced to Western Samoa, using artificially infected females as vectors Oryctes virus of rhinoceros beetle on coconut is one of few examples of successful use of an insect pathogen as a classical biological control agent

Key biological feature was survival of infected females long enough to vector virus to larval group feeding sites #5. Precedent for augmentative BC of greenhouse insects: Whiteflies are a long standing pest in greenhouse vegetable crops

Whitefly Encarisa formosa showed up nymphs spontaneously and was later commercially produced Commercial production methods for E. formosa were developed and a release card that allowed a repeatable number to be applied

As hung in the greenhouse

As received in the mail #6. Precedent for biopesticides based on insect pathogens: Healthy caterpillar vs one killed by Bacillus thuringiensis

healthy

Killed by Bt #7 Precedent for CBC of Weeds with Plant Pathogen: Skeleton weed infestations in Australian wheat fields Close up of skeleton weed plant Release of skeleton weed rust as a classical biological control agent MY formative experience with biological control: suppression of alfalfa by introduced parasitoids in the 1970s

Hypera postica, the alfalfa weevil, an invasive insect from Europe

In the 1970s most alfalfa (millions of acres) in the northeastern US had to be sprayed once or twice per year to control this insect Defoliation of alfalfa by alfalfa weevil larvae

Hypera postica, the alfalfa weevil, an invasive insect from Europe Defoliation of alfalfa by alfalfa weevil larvae Bathyplectes curculionis, an ichneumonid from Europe that attacks H. postica larvae Microctonus aethiopoides, a braconid that attacks H. postica adults, reducing oviposition before death

Control was complete in the eastern US, eliminating the need for annual pesticide applications on millions of acres alfalfa Kinds of natural enemies

• Parasitoids (against insect pests) • Predators (against insects and mites) • Herbivorous insects and mites (against plants) • Pathogens (against insects, mites, plants and vertebrates) Parasitoids

Diptera Hymenoptera • Tachinidae • Aphelinidae • and 11 other minor • Encyrtidae families • and 34 other families of some importance

TACHINIDAE

Compsilura concinnata an important tachinid of browntail moth APHELINIDAE (Aphytis melinus) on California red scale PREDATORS

Predatory Insects Other Predators • Many orders, • spiders especially species in • mites • Coleoptera • snails • Hemiptera • small mammals • Hymenoptera • birds • Diptera Coccinellidae- ladybirds-mostly generalist predators

Twice- stabbed ladybird Phytoseiidae- predaceous mites PATHOGENS

• Bacteria (e.g., Bacillus thuringiensis) • Viruses (e.g., NPV of gypsy moth) • Fungi (e.g., Beauveria bassiana) • Nematodes (e.g., Steinernema feltiae) • Protozoa (e.g., Nosema sp.) Bacillus thuringiensis healthy caterpillar (top) and Bt-killed one (bottom) Insect cells infected with NPV Fungus-killed caterpillar Entomophagous nematode-see stylet Nematode-killed termite HERBIVOROUS • MANY FAMILIES • Dactylopidae • • Chyrsomelidae • Tephritidae • Many moth families

Dactylopids are important for control of cacti Curculionidae-the weevil Crytobagous salviniae controlled Salvinia molesta