Natural Enemies Horticultural Allies. Natural Enemies Organisms that – –kill –decrease the...
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Transcript of Natural Enemies Horticultural Allies. Natural Enemies Organisms that – –kill –decrease the...
Natural Enemies
Horticultural Allies
Natural Enemies
• Organisms that – – kill– decrease the reproductive potential– or otherwise reduce the numbers – of another organism
• Can limit pest damage
Natural Enemies
• Reduce pest populations through– predation – parasitism– herbivory – competition– antibiosis
Predation
• Predators – – attack, kill and feed on several or many
other individuals
• Specialized predators – – feed on a single species or a few closely
related species
• Generalized predators – – feed on a variety of similar organisms
Predators
• Coleoptera – beetles• Hemiptera – true bugs• Diptera – flies• Neuroptera – lacewings • Hymenoptera – wasps• Arachnida – spiders• Vertebrates – birds, reptiles, coyotes,
etc.
Predators
• Predatory mites – family Phytoseiidae– controls pest mites and other insects
• Mites, collembola, flatworms, protozoa and some nematodes control pest nematodes
• Giant amoebae, various soilborne animals are pathogens to fungi and bacteria
Predators
• Birds, bats and fish prey on various insects and other pests
• Raptors, cats and coyotes prey on various pest birds, rodents and other vertebrates
Parasitism
• Parasites – – feed in or on a larger host– prolonged and specialized relationships
with hosts– typically parasitize only one host individual
in their lifetime
Parasites
• Disease producing bacteria, fungi, protozoa, viruses and some nematodes
• May attack invertebrates (insects and nematodes), weeds, pathogens and vertebrates
Parasites
• May weaken hosts without killing it
• Those that significantly weaken or kill the host are important natural enemies in biological control
Parasites
• Pathogens – – parasitic microorganisms – impair normal activities of host tissue or
cells– includes: bacteria, fungi, protozoa and
viruses
• Important controls of insects, nematodes, mites, weeds, and other pathogens
Parasites
• Parasitoid – – insect that parasitizes and kills other
invertebrates – parasitic in immature stage– kills hosts as they enter maturity– adults are free-living– adults about same size as hosts
• Can include – Hymenoptera and Diptera
Parasite vs. Parasitoid
• Parasites derives food from host organisms without killing the host
• Parasitoids end up killing the host before the parasite matures
Internal vs. External Parasites
• Endoparasite – internal– develops inside of the host
Internal vs. External Parasites
• Ectoparasite – external – develops while attached to the outside of
the host
Herbivory
• Herbivores – – animals that feed on plants– important natural enemies of weeds– specialized herbivores selectively feed on
one or several closely related weed species– some limit production by feeding on
flowers or seed
Competition
• Competition – – two or more organisms strive for the same
limited resources – i.e. food, water, shelter or light
• Can limit some weeds• Limited use as a biological control
Antibiosis
• Antibiosis – – substances secreted by organisms
inhibiting vital activities of other organisms
• May be useful in controlling some plant pathogens
• Few current applications
Common Natural Enemies
• Nematode-trapping fungi
Common Natural Enemies
• Predatory nematodes• Not particularly useful
in disturbed soils
Common Natural Enemies
• Decollate snails control . . . – European brown garden snails– citrus thrips – feeds on pupae in soil– can feed on seedlings
Common Natural Enemies
• Predatory mites– occurs in several families– tend to pear-shaped, longer-legged and
shinier than pest mites– more active than plant-feeding mites– feeds on plant-feeding mites, insect eggs,
immatures – crawler stages of scale, thrips and whitefly nymphs
– translucent, bright white, red, yellow, green
Common Natural Enemies
Common Natural Enemies
• Parasitoid wasps control . . . – various Homopterans including: aphids,
whitefly, scale, psyllids, mealybugs, and a host of other pests . . .
– as well as various Lepidopterans
Common Natural Enemies
• Lacewings (Order Neuroptera)– larvae are predaceous– not adults from all species are– feeds on aphids, whiteflies, mealybugs,
caterpillars, mites, psyllids, insect eggs, and other insects
Common Natural Enemies
• Green Lacewing (Chrysopidae)
Common Natural Enemies
• Brown Lacewing (Hemerobiidae)
Common Natural Enemies
• Lady Beetles (Coccinellidae)– over 500 species in America– most are predaceous as larvae and adults– many are prey-specific including various
insects and mites
Common Natural Enemies
Common Natural Enemies
Common Natural Enemies
Common Natural Enemies
• Assassin bugs (Reduviidae) – over 160 species in North America– all are predaceous– some attack mammals– Feeds on a range of insect pests
Common Natural Enemies
• Damsel bugs (Nabidae)– predaceous on mites, aphids, caterpillars,
leafhoppers, etc.– resembles small Reduviidae – long front appendages
Common Natural Enemies
• Syrphid flies (Syrphidae)– AKA hover flies, flower flies– larvae are predaceous – adults often resemble honey bees– feeds on aphids and other soft-bodied
insects
Common Natural Enemies
• Mantids (Mantidae)– praying mantids
or praying mantises
– predaceous – elongated thorax– long, grasping
forelegs – opportunistic and
cannibalistic