Biological controlsBy

Jen H. and Amanda P.

Biological controls are the use of living organisms

 to reduce the incidence of pestorganisms

Encarsia formosa

Delphastus pusillis

These are two predatory insects in our tomato bay!

Why use biological pest controls?

-They are specific to the pest or pests we desire to control

-They consist of insects or insect diseases caused by bacteria, protozoa, viruses, or fungi, all natural

-They are effective against the target insect but are generally nontoxic to humans, pets, wildlife, and beneficial insects

-They typically break down quickly in the environment, which means shorter reentry times

-They are less likely to produce resistance than chemical pesticides

Disadvantages of using biological controls

-It is management intensive

-It requires more observation and knowledge than traditional pest management techniques

-Proper pest species identification is critical to success in choosing right biological control

-Release rate, timing, placement, temperature, and pesticide use affect performance of biological controls

-Wide varieties of crops make the choice of biological controls more difficult as the numbers of pests increase and vary

-Biological controls take more time to work than traditional methods

-No single biological is 100% effective

Biological controls can be used in both the greenhouse and the garden.

Examples of some common garden pests and their biological controls are

PEST BIOLOGICAL CONTROL

Aphid Hippodamia convergens (ladybug)Chrysopa carnea (lacewing)Tenodera aridifolia sinensis (praying mantis)

Thrips Amblyseius cucumeris

Mosquito Bacillus thuringiensis, Bt israeliensis

Grasshopper Nosema locustae, also chickens and ducks!

Goat head weed Microlarinus lareynii (puncturevine weevil)

Examples of biological controls we use in our greenhouse at Yavapai College

Encarsia formosa – parasitic wasp which feeds on whitefly

Delphastus pusillus – small black beetle which also feeds on whitefly

Mycostop – a naturally occurring bacteria, creates a defense against Botrytis

Guardian – contains nematodes which kill fungus gnats and shore flies

BotaniGard – contains fungus that attacks aphids, whitefly, thrips, and spider mites

Gnatrol – contains bacteria that kill fungus gnat larvae

Mycostop

-Contains dried spores and mycelium of Streptomyces griseoviridis Strain K61

-Comes in the form of dry powder, which can be mixed with water and used as a spray

-When applied as a drench or a spray, the dried spores and mycelium germinate and begin to grow around the plant’s roots

-The Streptomyces infects pathogenic fungi which cause diseases such as wilt and root rot. Mycostop is known by growers to kill Fusarium, Botrytis, Pythium, Alternaria, Phomopsis, and to a lesser extent, Rhizoctonia and Phytopthora

Guardian/Gnat Patrol

-Contains live nematodes Steinernema carpocapsae and Steinernema feltiae

-Comes on small sponges, which are soaked in water. Use the water as a spray

-Used to control fungus gnats but also kills more than 250 different insects

-Very tough, can survive in the root zone of plants for 60-90 days without a host insect. Covered with a cuticle which makes them resistant to most chemicals, fungicides, insecticides, and environmental conditions

-Detects insects by either a slight increase in temperature or by release of methane gas, and they can travel about 1” per hour to seek out insect hosts

-Kills insects by entering the insect, shedding their cuticles, and releasing bacteria which actually kills the insect; kills insect in 16-28 hours

BotaniGard

-Contains spores of the fungus Beauveria bassiana

-Comes in the form of a dry powder, which can be mixed as a spray

-Known by growers to control aphids, whitefly, thrips, mealybugs, and spider mites

-Spores attach to the insect, forming an enzyme which dissolves the insect’s cuticle. The fungus germinates and invades the insect’s body

-Compatible with predators such as Encarsia formosa

Gnatrol

-Contains Bacillus thuringiensis israelensis

-The bacteria disable fungus gnat larvae by paralysis. The gnat larvae then stop feeding on the plant and die, usually within 24 hours

-The bacteria does not kill adult fungus gnats

-Can be applied as a soil drench around the base of the plant, as a spray, or through an irrigation system

FactsEncarsia formosa

•used worldwide for commercial control of whiteflies

•Commercial use began in Europe in the 1920s

•small (~ 0.6mm in length), have a black head and thorax and yellow abdomen. Males are rare and dark in color.

•To successfully reproduce in greenhouses, E. formosa must locate potential hosts, assess host quality, and use nymphs appropriately for host feeding or parasitism. Following release into the hosts' habitat (i.e., greenhouses), E. formosa employs visual and olfactory cues to find infested host plants

•endoparasitoid that matures 8-10 eggs per day

Delphastus pusillisFacts

•Is a small black 'ladybug' from Australia that will consume about 150 whitefly eggs per day.

•They are about 1/8" diameter and will disappear into the plant canopy very quickly.

•They are recommended for moderate to heavy infestations (10 - 15 whitefly larvae per leaf). This small beetle is used to provide control of the greenhouse, sweet potato and silverleaf whitefly.

•They work well in areas with great diversity by hunting and eating immature whiteflies and especially, the eggs. This predatory beetle will sometimes consume spider mites. Both the adults and larvae are predacious. Delphastus pusillus beetles have a tremendous appetite.

References

ATTRA Publication, “Integrated Pest Management For Greenhouse Crops” Pest Management Systems Guide

Bioworkshttp://www.bioworksinc.com/products/shared/botanigard.pdf

Chem-Grohttp://www.chem-gro.com/PDF%20Files/GnatPaper.pdf

Cornell Universityhttp://www.nysaes.cornell.edu/ent/biocontrol/parasitoids/eformosa.html

Hydro-Gardenshttp://www.hydro-gardens.com/whitefly.htm