Mite Morphology And Physiology

Front 1

Describe the differences between mites and insects in their basic body organization.

Back 1

Unlike insects, which have head, thorax, and abdomen, the Acari have only 2 segments- the gnathosoma (pair of chelicerae and pair of palps) and the idiosoma (the rest of the body including the region with the legs. There is no "head." No antennae although the first pair of legs often antennae-like. Four pairs of legs except in family Eriophyidae which has 2. No wings. Condensed systems. Chelicerae instead of mandibles.

Front 2

List the major taxonomic categories for mites.

Back 2

Phylum Arthropoda
Subphylum Chelicerata
Class Arachnida
Subclass Acari (Acarina)
Order Parasitiformes (contains Phytoseiidae and ticks)
Suborder Gamasida (Mesostigmata)- Phytoseiidae
Suborder Ixodida (Metastigmata) - ticks
Order Acariformes
Suborder Actinedida (Prostigmata) - Tetranychidae, Eriophyidae, Tarsonemidae, Tydeidae
Suborder Acaridida (Astigmata) - stored product mites
Suborder Oribatida (Cryptostigmata) - soil or beetle mites

Front 3

Define idiosoma.

Back 3

The body segment that includes the rest of the body including the region with the legs.

Front 4

Define podosoma.

Back 4

The region containing the legs.

Front 5

Define opisthosoma.

Back 5

The region behind the legs.

Front 6

Define gnathosoma.

Back 6

The segment containing the pair of chelicerae and pair of palps.

Front 7

Define propodosoma.

Back 7

The region containing the first 2 pair of legs.

Front 8

What kind of chelicerae do the different members of Acari have?

Back 8

Ticks have a specialized hypostome that is a bar bed piercing organ with retrorse teeth. Spider mites have chlicerae that are highly modified and stylet-like. Most have chelate-dentate chelicerae

Front 9

Why could there be more mite species than insect species?

Back 9

Mites are smaller and are able to occupy smaller niches than insects. They also rival the insects in the diversity of habitats they colonize such as terresrial, fresh water, oceans, parasitic on plants, vertebrates or invertebrate animals.

Front 10

What is agricultural acarology?

Back 10

the study of mites if importance to agriculture

Front 11

Define peritreme.

Back 11

also called stigma, which is the opening to the respiratory system

Front 12

Define hypostome.

Back 12

barbed piercing organ of ticks

Front 13

What is a spermatodactyl?

Back 13

a chelicerae modification that is used for transferring spermatophores to the sperm receptacle of the female.

Front 14

What are pedipalps?

Back 14

they are used as sensory appendages and sometimes become modified for grasping food; there are also used for cleaning the chelicerae after feeding.

Front 15

What is the typical digestive tract of a mite?

Back 15

it includes the mouth, which opens into a muscular pharynx connected to the stomach or ventriculus by a long esophagus. The esophagus passes through the "brain" of the mite. A hindgut, divided into anterior and posterior regions opens to the exterior either terminally or subterminally. The gut is usually provided with a nuber of paired diverticula. In some mites, a pair of malpighian tubes may open into the hindgut. Paired salivary glands are associated with the alimentary canal.

Front 16

Excretions from mites come out as what form?

Back 16

guanine

Front 17

Mites have a more diffult time surviving in the environment than insects. Why? What physiological limitations do mites have compared to insects?

Back 17

Mites must maintain the water content of their body. Terrestrial species continually lose water that must be replaced and the aquatic species continually gain water that must be eliminated. This is due to mites being much smaller than insects and thus have a higher surface-to-volume ratio than insects.

Front 18

How is water conserved in mites?

Back 18

Most terrestrial mites are cryptic and are found primarily in sites where high relative humidity reducing the rate at which water is lost to the air. Water is also conserved by the epicuticle. Coxal glands help maintain water and ionic balance, especially in ticks.

Front 19

What is a cultural control method for pest grain mites?

Back 19

dry the grain and store it in a dry environment

Front 20

Spider mites intake too much fluid so how do they deal with that?

Back 20

They have a specialized digestive tract, in which the excess fluids are shunted from the esophagus to the hindgut for elimination.

Front 21

How does the muscles of mites differ from insects?

Back 21

The number of muscles in mites is reduced as compared to the muscles in insects.

Front 22

What are the 2 main types of muscles in mites?

Back 22

- Intrinsic which extend over the joints of leg segments are are flexors.
- Extrinsic muscles are those of the body and consist of dorso-ventral, oblique, rotator and elevator muscles. They originate and insert on the body wall.

Front 23

What side of the mite do muscles originate and how do they modify the shape of the body?

Back 23

- located dorsoventral
- modifies the turgor pressure of the body fluids. Hydrostatic pressure causes the extension of the chelicerae, palps and legs.

Front 24

Describe the respiratory systems of the different mite suborders.

Back 24

The location of the stigmata vary.
- Astigmata - absorbs gases through skin
- Prostigmata - opening is in front of body
- Cryptostigmata - opening is hidden
- Metastigmata - stigmatal openings on special plates just behind the fourth pair of legs
- Mesostigmata - stigmata opening on the side of the body between the legs on a peritrematal shield

Front 25

Describe the nervous system of a mite.

Back 25

The embryonic arachnid nervous system is similar to that of other arthropods and has ganglia in each segment, but the nervous system of mites has become greatly consolidated. It has become condensed into a compact, unsegmented mass. No central nerve cord or ganlia are found in the opisthosoma and nerves arise from this single concentrated mass.

Front 26

Describe the sensory system of a mite.

Back 26

Most of the sensory structures on the body and legs of mites are setalike, although some pores are also sensory. Many are tactile, some are chemosensory and some may be involved in detecting relative humidity. All eyes are simple with a cup-shaped retina. Legs and palps contain numerous sensory receptors.

Front 27

Someone brings you a small arthropod for identification. How do you decide that you have a mite? How might you identify it?

Back 27

To decide if I had a mite, I would count the number of legs and see if it had two body segments. I would identify it by mounting it to a slide and using a phase-contrast microscope. Setal structure and location could help identify it further.

Front 28

Describe the circulatory system of a mite.

Back 28

The circulatory system in the mites is an open system, with the blood bathing the internal organs. The blood is typically colorless and contains numerous blood cells. The blood circulates by the movement of the dorsal-ventral muscles or, sometimes, by a circulatory organ called a "heart."

Front 29

What is an aedeagus?

Back 29

male intromittent organ for transfer of sperm to females

Front 30

What is a hypopus?

Back 30

a phoretic deutonymphal stage

Front 31

What is phoresy?

Back 31

hitching a ride on another organism such as an insect

Front 32

What is the typical life cycle for a two-spotted spider mite?

Back 32

egg --> larva --> protonymph --> deutonymph --> adult (male and female)

Front 33

C/C diapause and quiescence.

Back 33

Diapause is a genetically determined state of reduced metabolic activity which typically is induced prior to the onset of unfavorable conditions. Temperature and photoperiod determine it. Quiescence, which occurs in direct response to adverse physical conditions, is terminated as soon as favorable conditions return.

Front 34

How can mites by dispersed?

Back 34

- walking
- aerial dispersal, involving silking or other specific behaviors
- phoresy
- as aerial plankton, in which they are picked up and blown long distances

Front 35

What life stage is usually dispersed in two-spotted spider mites and predatory mites and how do they disperse?

Back 35

adult mated females that have not yet begun to oviposit so they are not yet weighed down by their relatively large eggs.
Spider mites are dispersed by silk strands and predatory mites stand on their hind legs and blown away.

Front 36

C/C arrhenotoky and thelytoky.

Back 36

Arrhenotoky is a genetic system where unmated female tetranychids can produce eggs that develop into haploid males. Thelytoky is where unfertilized eggs produce females only.

Front 37

How does arrhenotoky allow pesticide resistance to develop rapidly?

Back 37

Because males in the Tetranychidae are haploid, any new mutations are immediately exposed to selection in the male, so if a male is exposed to pesticides and a single copy of resistance gene is present, the resistance gene will be selected for.

Front 38

What increases the likelihood that a favorable mutation will be selected?

Back 38

the combination of sib mating and haplo-diploidy leads to a rapid fixation of any new favorable alleles in a population; therefore, haplo-diploid spider mite species can respond rapidly to selection for resistance to pesticides or for the ability to survive on new host plants.

Front 39

Describe the reproductive system of mites.

Back 39

Mites have both direct and indirect sperm transfer. Males that transfer sperm directly into the sperm receptacle of the female often have special structures for grasping the females during copulation. Tetranychidae have an aedeagus, while Phytoseiidae have a spermatodactyl.
Indirect sperm transfer involves deposition of a sperm packet (spermatophore) on the substrate by males then the females pick up the spermatophores and place them in their sperm receptacle.

Front 40

Why do males guard female deutonymphs?

Back 40

The female produces a sex pheromone that elicits the "guarding" behavior.

Front 41

What is the mating behavior of T. urticae?

Back 41

T. urticae males touch the female with his forelegs. Next, the male crawls under her and holds on by clasping her third and fourth pair of legs with his first 2 pair of legs. At the same time, the idiosoma of the male is arched upwards so that the aedeagus is introduced into hte genital opening of the female. At this stage, the female will permit a full coputlation to occur or will terminate the mating.

Front 42

Describe parahaploidy.

Back 42

All eggs must be fertilized. Phytoseiid eggs that produce females remain diploid. In males, the diploid eggs undergo development, but about halfway through embryogenesis one half of the chromosomes are heterochromatinized and eliminated from the cells, leaving the male haploid for the rest of his life- having only the females genes.