module 10 Flashcards
Biological control
Uses natural predators of pests for control
Biological control uses
trophic interaction
1st trophic levels
Autotrophs plants
2nd order trophic level
1st order consumer
3rd order trophic level
2nd order consumer
3rd trophic order
Top predator that feeds on carnivores
Biological control agents exmaples
Predators
Parasitoids
Pathogens
herbivores
Parasitoids
Larval stage infects and kills arthropod hosts
Feed on internal organs of host
Once larval stage is done, the free living parasitoid
Exits the host to mate and seek a new host
Parasitoid organisms belong to the orders
Hymenoptera and diptera
Which gender contributed to parasitoids
Ovipositing females
Strepsipteran
Order of insects that are all parasitoids
Parasitoids that develop within the host are known as
Endoparasitoids
Parasitoids that develop on the host
Ectoparasitoids
Parasitoids that develop while the host grows are known as
Koinobiont
Idiobiont parasitoids
Feed on host and paralyze them
Exclusively ectoparasitoids
Superparasitism
Individuals are attacked multiple times by individuals of the same species
Superparasitism is mostly
Avoided because it promotes competition between parasites
What do parasites use to identify and avoid hosts that are parasitized
Antannae or ovipositors that are specialized to do this
Multiparasitism
When a host is parasitized by multiple parasites
Leads to interspecific competition and the only one species of parasite often emerges
Multiparasitism is more
Likely than superparasitism
Hyperparasitism
the larvae or pupae of a parasitoid serves as the host for another parasite
Hyperparasitoid larvae feed on
Other parasites associated with the original host
Can get in the way of IPM
Common defence mechanism for parasitism
Encapsulation
Encapsulation
Host hemocyte surround the parasite larva and cut off its access to oxygen and nutrition
Parasitoid resistance to encapsulation
Turns the hemocyte capsule into a protective sheath for the parasite larva
Some parasitoids have mutualistic relationships with
Viruses
Help suppress host immune responses
Some parasitoids avoid the host immune system by placing larvae in
Certain areas that easily compromised such as the fat body or ganglia of the CNS
Parasitoids have co-evolved with the
Hosts they inhabit changes nervous system
Ectoparasitoid wasps with spiders
Larvae make spiders spin a cocoon web for them
Bodyguard manipulation
Larvae that have pupated are protected by host after they have left the host body
Predators
free living organisms that feed o other animals
Most insect predators are
Generalists
Common arthropod predators used for biological control
Ladybird beetles
predatory mites
Lacewings
Ladybird beetles are used to manage
Aphids and mites
Lacewing are used to control
Aphids
Predatory mites are used to control
Other mites
Predators are used when pest population is
low
Vespid wasps
Most are predators and are used as control for herbivorous insects
Pathogens
Bacterial
Fungi
Microphages
Bacillus thuingiensis (bt)
Different strains affect different insects so it provides targeted control
Fungi attack insects through their
Intact cuticle
Grow on insect and produce toxins that impact the insect
Beauveria bassina
Spores of this fungus can be applied to whiteflies and aphid populations
fungal control has very little effect on
Other organisms and have mass use cases
Baculovirus
Pathogens that attack arthropods and have a wide range that attack certain insects
Baculovirus affects insects by
Being consumed by the insect and leading to them basically dissolving and releasing the virus onto surrounding surfaces where other insects come into contact
Baculovirus specific formulation to target
Gypsy moths to protect forests
Baculovirus breakdown in the environment
quickly
Baculovirus cost is
High because each type of virus must be made for a specific insect
Microbiome
A community of microorganisms that protect the organism host from disease
Effects of targeting the pest microbiome
Decreased growth rate
Diminished reproductive success
Reduction in the ability of the insect to transmit disease
Pest management targeting the pests microbiome
Introduce a new organism
Genetically modify microorganisms already present
target and eliminate microorganisms that essential to the insect
Biological control agents can be used in
weed management using herbivorous arthropods
What are biological control agents for weeds
Plant pathogens or herbivores
Weeds
Unwanted plants that grow in competition of crops
Can be harmful to plants or humans
Yellow toadflax weeds are controlled by
Toadflax weevil
Three most common biological control approaches
Classical
Augmentative
Conservation
Classical biological control
Introduction of non-native biological control agents to deal with pests
Classical biological control is used to
control but not eradicate
Alfafa weevil is dealt with
Classical biological control
12 species of parasitoids were introduced to control the alfalfa weevil
Augmentative biological control
Active manipulation of populations of biological control agents
often means the release of a natural predator
Augmentative biological control methods
Inoculative
Inundative
inoculative Augmentative biological control
Frequent well-timed release of control agents
Inundative Augmentative biological control
All biological control agents are release at once
goal is to overwhelm the pests immediately
Inoculative example
Whiteflies
Wasp population is used to deal with whiteflies by laying their eggs in the fly
Inundative control example
use of BT
Application of BT is used to kill pest population in one go
Bacteria is killed off by sunlight but lasts in soil for a year
Beneficial traits in biological control agents
Pesticide and disease resistance
Temperature hardiness
Manipulate sex ratios
Conservation biological control
Specific variables in the environment are changed to promote natural enemies of pest in a ecosystem
Parasitoid wasp populations assisting with corn
conservation biological control
Forested areas surround corn crops and the wasps live in them and move into the corn later in the season to feed on pests
Natural habitats may be have resources or alternative hosts needed for
Parasitoids
Anagrus parasitoid wasp
Conservation biological control example
The wasps parasitize grape leafhoppers but the leafhoppers overwinter as adults so they cannot be parasitized in the winter
Alternative hosts are provided that overwinter as eggs for the wasps to parasitize and this allows them to survive and then deal with leafhoppers in the warmer climate
Banker plants
Non-crop plants that support that have non-pest herbivores that help support the natural predator of a pest in the system
Banker plants allows managers to
Use a single species of natural enemy rather than a suite of enemies that compete or predate each other
Conservation biological control is more
sustainable
Biological control advantages
Cheaper both environmentally and economically
Less likely to affect other organisms
Biological control being cheaper
Rearing and introducing a biological control may take a lot of resources, but if the population becomes established, then there will be no further need to follow up
The most affordable form of biological control is
Conservation
Biological control and chemical control can be
effective in IPMs
Biological control requires
Thorough understanding of the species and environment
Asian ladybird beetle
Introduced as biological control for aphids
Ended up competing with native ladybird beetles
Asian ladybird beetle is now the predominant ladybird beetle
The use of biological control agents with a limited host range means that
There might be more agents required to look after an area which can be costly
Diversity of plants in ecosystems can
Complicate use of biological controls
More diversity of plants means more types of pests means more methods of control means more money
Time it takes for biological control is a
Lagging effect and may be a problem because they may not be able to help high value crops or deal with dangerous pests immediately
Biological control agents shelf life is
Short unlike chemical agents because they are living organisms
Chemical control is better as a
Short term fix
Cultural control/ecological management
Purposeful control of environment factors to reduce the number of pests
cultural control involves
Changing the environment or removing the environments for pests to survive
Tillage
Technique used in agriculture that mechanically disturbs soil
Can expose insects to the environment and disturb their homes
Soil dwelling insects become exposed
Temperature as a cultural control
temporarily changing the temp in order to make the environment inhospitable
used against bed bugs
Another cultural control method is the removal of
Pest access to resources
Also destroy alternate hosts
Crop rotation
Alternating what type of crop is planted in consecutive seasons
Mitigates the buildup of pests that specialize in one crop
Crop rotation is important to deal with the
Wester corn rootworm beetle
Larvae feed on roots of corn plants after winter
By alternating crops, the specialist larvae die
Alternating crop planting times example
Aphids feed on young plants in the summer that were just planted
By planting these plants earlier, they will be mature in the summer and the aphids will be less likely to feed
Trap cropping
Planting crops next to the main crops that are attractive to the pest
Divert pest infestation and the pests are controlled in the trap crops
Insecticides and lures are used when insects are trap cropped
Intercropping
Planting multiple crops in the same area
Makes field less attractive to pests and increases yield
When onions are planted next to carrots
It diverts flies
example of intercropping
Trap trees
Lure is placed on trap tree and then the tree is moved
kills pest
Insect netting
Protects crops and people
Host resistance to pests can be changed through
Selective breeding
Genetic engineering
Non-preference defence
Physical or chemical traits that prevent pests from finding or accepting the host plant
Antibiosis
Plant trait that interfere with an insects metabolism
tolerance
By increasing presence to pests, the crop becomes more tolerant
Compensatory growth example
Damaged corn plants by beetles grow longer roots when they grow back and have higher yield
No selection pressure is placed on pests as a result of
Host tolerance
The pests cannot development resistant to hosts that have tolerance
The effectiveness of tolerance depends on
Host and environmental conditions
Increasing host tolerance can be done by
Increasing fertilizer use or just selecting those with higher resistance
Selective breeding can take
Many generations
Genetically modified organisms (GMOs)
Genetic engineering
Allows us to target genes using molecular processes
Transgenic organism
Genetically modified organisms that has increased pest defence and herbicide resistance
Ways desired genes can be transferred into a host
Injected into fertilized egg to allow it to integrate into cell
Use a bacterial vector to integrate DNA into target
Genetically modified animals are not
Feasible while plants are
BT crops
BT is put into plants and plants produce BT toxin
Can be deadly to insects and lead to them developing resistance to BT crops
BT resistance can be combated by planting
Refugia next to plant that is being protected
RNA interference crop (RNAi)
RNA molecules that bind to mRNA during protein synthesis and prevents the reading of mRNA to turn it into codons
RNA interference crop (RNAi) is known as
Post-transcriptional gene silencing because the genes have already been transcribed into mRNA
RNAi inhibits the synthesis of
Enzymes used to fight plant toxins
Sterile individual introduction
Pests mate with sterile individuals and it leads to no offspring, negatively affecting the population
