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24 Cards in this Set

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  • Back
Define spider-mite day.
the damage caused by one spider mite feeding for one day
If your chemical control did not work, what could have happened?
pesticide resistance, pesticide applicator could have mixed the product improperly, coverage many have been inadequate, the pH of the water used to mix the pesticide could have altered the toxicity of the product, and the product could have been old or degraded due to improper storage.
Spray-rig nozzles may have been calibrated incorrectly, the grower may have driven the rig too fast so that too little product was applied.
The integrated mite management program in California almonds included several different tactics. Describe them. What unusual features did this program have?
The IMM program in almonds in CA included:
- using selective pesticides (low toxicity to predators) to control insect pests
- monitoring (number of spider-mite days) to be sure acaricide treatments were applied when needed
- using a low rate of acaricide (1/10 the normal rate of propargite or 'spot treating' hot spots only) to leave some prey for this obligatory predator
- (if necessary) releasing pesticide-resistant M. occidentalis (carbaryl-OP resistant)
- irrigating correctly to maintain tree vigor
- reducing dust (roads near the orchard are oiled or paved)
Why is classical biological control the appropriate strategy for managing this particular cassava green mite in Africa?
- the pest is not native to Africa
- it cannot be controlled readily any other way
- chemical control is too expensive for substinence farmers
- lending support to the hypothesis that effective natural enemies might exist in S. Am., there is no history of prolonged and severe mite attacks on cassava in Latin America prion to the introduction of CGM into Africa
Describe the classical biolgical control program for the cassava green mite in Africa.
- The strategy was to explore areas in the Neotropics that correspond ecologically to the very large and climatically diverse areas in Africa where the CGM is a pest and to identify ecological homologues between the continents. As species were identified, several biological traits were studied and the data were added to a database for evaluating the predators for potential release in Africa.
- Typhlodromalus aripo was released in Africa beginning in 1993. It became widely established. The phytoseiid spread over a wide area within 2 years. It is specific to CGM.
- Unique mass rearing methods are aerial application methods were developed.
Because mites are small, you have learned about methods for sampling mites in agriculture. Describe the techniques and how they are used.
Presence-absence sampling where a certain number of leaves are sampled to looked to see if pest and predator mites are simply present or absent
Brush and count method using either a mite-brushing machine or paint brush to count the number of mites per leaf; more laborious but provides more detailed info such as mean number of spider mites and predators per leaf, pradator:spider mite ratios, and accumulated spider mite-days
What key points did IMM in grapes include?
1) Mites may be induced by pesticide applications since most are resistant and their predators are killed.
2) Selective insecticides and acaricides are important
3) Cultural controls such as dust and water management are important.
4) Sulfur resistance developed in M. occidentalis was key to its use in grapes in CA to control spider mites which were also resistant to sulfur.
5) Tydeids in CA vineyards are important as alternative prey for M. occidentalis, especially early in spring and in autumn and winter, This is a 'community of mites.'
6) The desired predator:prey ratio in CA vineyards is 10:1 to 2:1.
7) Host plant resistance in grapes is "not an option."
What are the key steps in classical biological control?
1) Determine the pest is foreign.
2) Determine the pest problem justifies the effort.
3) Determine the pest is a good candidate for classical biological control.
4) Conduct a survey for the pest and its natural enemies in its area of origin.
5)The area of origin of the pest is the likely site of the greatest diversity of natural enemy species.
6) The natural enemy must be able to establish in the new environment.
7) Information must be obtained on the biology of the natural enemy.
8) Importation of natural enemies into the USA is regulated by state and federal agencies.
9) A priority list has to be made and one to several species evaluated for possible release.
10) The natural enemy should not pose a risk to agriculture or to the environment.
11) Release methods should be carefully considered.
12) Evaluate for establishment.
13) Evaluate its impact.
14) It is rare that a SINGLE natural enemy is able to control a pest.
15) Conduct an economic assessment so that the costs and benefits of the program can be calculated.
What is the species of Tenuipalpidae that is of great economic concern currently and what damage does it cause?
Raoiella indica, the red palm mite, causes serious economic injury to palms, bananas and plantains by causing extensive yellowing to the lower leaves.
What pest causes citrus leprosis?
Brevipalpus californicus, the citrus flat mite, family Tenuipalpidae. It injects toxic substances during feeding on citrus causing nail-head-rust on leaves and fruits.
Eriophyids are relatively host-specific agricultural pests. Describe the types of damage they do.
Eriophyids are called blister mites, rust mites, bud mites or gall mites because their feeding causes different types of damage to plants.
Buds are injured when eriophyids feed on their surface or when they cause gall formation.
Eriophyids can also cause "witches broom" of twigs, flower galls, shortening of internodes, or secondary development of leaf hairs.
Some eriophyids are considered beneficial. Why?
The apple rust mite is considered a beneficial species in Washington apple orchards under an IMM program because these mites serve as prey for M. occidentalis early in the growing season. Apple rust mites allow predator populations to increase so they can suppress the spider mite pests on apples later in the growing season.
Describe cyclamen and broad mites. How can they be controlled?
Cyclamen mites and broad mites are tarsonemids. They have broad host ranges. Broad mites have oval bumpy eggs.
Tarsonemids usually are found in damp, shady places and feed on the lower leaf surface and is restricted to young foliage or flower parts. This causes curling and crinkling of leaves followed by patches of blisters.
Phoresy on aphids and whiteflies occurs with these mites.
Control is with sulfur and a fungal pathogen Hirsutella nodulosa infects broad mite.
Give the biology of a representative species of Penthaleidae.
Redlegged Earth Mite
- RLEM life cycle is: egg --> larva --> protonymph --> deutonymph --> tritonymph --> adult
- Males produce spermatophores
- Eggs exhibit an aestival diapause which are drought-resistant
- Females die with their bodies full of diapausing eggs
- Damage is seen as silvering of the leaf as a result of damaged cells. It also taints forage in pastures
Mites are serious pests of honeybees. Name the two important species of mites that attack hive bees in the USA.
Acarapis woodi, the tracheal mite and Varroa destructor, the Varroa mite
Describe the biology and damage of the tracheal mite. How can they be managed?
The tracheal mite is a tarsonemid (Actinedida/Prostigmata); it is the only internal mite attacking honey bees.
- These tiny mites infest the tracheal system of adult bees, feeding on hemolymph, reducing the bee's longevity by impairing the ability of the bees to fly and weakening them so they die of starvation or exposure.
- The mite passes through its life cycle in the tracheae of the bee and all life stages are found there.
- Fertilized adult females leave the tracheae to colonize a new host, apparently attracted to particular hydrocarbons from the cuticle of bees less than 4 days old. Once a suitable host is found, the female enters a trachea and lays approximately 20-25 eggs over 25 to 30 days.
- Life history is egg--larva--pharate adult--adult
- Causes decreased honey production, decreased brood production, and increased winter mortality of colonies
- Control by feeding bee colonies "grease patties" during the fall and winter. The oil conceals young bee odor.
Describe the biology and damage of the varroa mite. How can they be managed?
V. destructor requires high temps and high RH and reproduces on both capped drone (males) and worker brood (sterile female workers)
- Large, dorsoventrally flattened, heavily sclerotized reddish-brown mites.
- The reproductive cycle of Varroa requires that the female move from adult bees to the cells of bee larvae. Varroa females enter the brood cell of a larval bee shortly before the cell is sealed. The Varroa female may feed on the bee larva but quickly crawls underneath the larva and immerses itself in the brood food provided by the worker bees. The Varroa female remains in the brood food, ventral side towards the opening of the cell until the bee larva eats the food, cleaning and freeing the Varroa.
- As mites are freed, most of them die, but those that survive begin feeding on the hemolymph of the larval and later the pupal bee.
- Reduced honey produciton and weak or killed colonies can result.
- Varroa is thought to transfer the acute paralysis virus from unhealthy bees to healthy bees, or stress activates it.
- Control: resistant bees may be developed through selection.
What families of mites would be considered beneficial?
Anystidae, Hypoaspidae, Tydeidae
The integrated mite management programs in California citrus included a variety of tactics. Briefly describe the tactics employed.
Citrus is grown in four major areas in CA, each with distinctly different climates, ranging from the desert to the coastal-intermediate region. Pest management practices and pests vary with citrus-production region.
Tactics involve:
- monitoring
- biological control (i.e. Euseius tularensis)
- dust management
- chemical control (sulfur and difocol, but toxic to predators)
What is the difference between pest management in CA compared to FL?
In CA, the importance of pests varies by climatic region and citrus variety. The major insect pest of citrus in the San Joaquin Valley is the California red scale. In FL, there is more uniform soil, climate and pests with the most important mite pest is the citrus rust mite
Although phytoseiids are premier predators of pest spider mites, they are also important predators of some insect pests. Describe the role phytoseiids play in citrus pest management in CA.
Citrus thrips are also significant pests of citrus in the San Joaquin Valley because the thrips feed on epidermal cells of the fruit, leaving scabby scars on the rind, which causes a conspicuous ring and makes the fruit unmarketable as fresh fruit. The cosmetic damages have no effect on fruit quality. A predatory mite (Eusius tularensis) is an important predator of citrus thrips.
Define transovarial transmission.
transmission of pathogens from mother to progeny
Define transstadial transmission.
transmission of pathogens from instar to instar
Mites are important post-havest pests of agricultural and ornamental crops. Describe the types of damage they can do and list some key mite species. How can these pests be managed?
In family Acaridae
- for pantry and stored food pests, keepp foods in tightly closed containers, freeze for several days, inspect foods, clean shelves
Bulb mites damages bulbs exhibit brown rotting tissue around the neck of the bulb; leaves and flowers that develop may be delayed and abnormal
- Acaridae sometimes produce a different second nymphal stage called a hypopus that are nonfeeding and are adapted to surviving long periods without food.