|
![[Under Construction]](images/undercon.gif)
| |
MITES
This module
is intended to serve as a source of basic information needed to implement an
integrated pest management program for mites. Any pest management plan or
activity must be formulated within the framework of the management zones where
it will be implemented. Full consideration must be given to threatened and
endangered species, natural and cultural resources, human health and safety, and
the legal mandates of the individual parks. Recommendations in this module must
be evaluated and applied in relation to these broader considerations.
Mites are members of the order Acarina, which also includes ticks. Hundreds of
species of mites occur in the United States. This module describes life
histories and integrated pest management strategies for seven species that have
been found to be of greatest concern in the National Park System. Six of the
mite species in this package are in the family Tetranychidae (which includes the
mites commonly known as spider mites), while the seventh, the eriophyid mites,
are in the family Eriophyidae. All are extremely small, requiring a hand lens to
determine their presence and numbers. Mites do not have a true head, wings, or
abdomen. There are four pairs of legs and a pair of leg-like palps associated
with the mouthparts. Mouthparts consist of a pair of needle-like stylets
(chelicerae) used to pierce cell walls, allowing the mouth to suck up cell
contents. This is important because the type of mouthpart creates the stippled
appearance associated with Tetranychid mite injury. The injury caused by
Eriophyid mites is much more variable, and includes yellowed foliage, distorted
foliage, or a variety of leaf and petiole galls. Mite-feeding injury is often
confused with injury caused by insects or air pollution. Refer to Table 1 for
more information on differentiating mite and insect injury.
Table 1. Plant pests and diseases which produce injury similar to
mites
PESTS SYMPTOMS DETECTION CONTROL /
PREVENTION
Tetranychid Leaves or Tap branches Dormant oil
mites needles get onto white in late winter;
pale yellow paper and insecticidal soap,
to bronze examine with summer oil or
stippled areas a 10X hand miticide at
at any time lens for other times as
from early small green needed.
spring on. or red spiders Ref: Grossman;
Usually on or shiny Johnson and Lyon
one-year-old round eggs.
growth of White cast
conifers and skins may
new growth be seen on
of broad- leaf undersides.
leaved and Look for
deciduous eggs at any
plants. time, mites
when
temperatures
are above 50
degrees.
Eriophyid Yellow to Look for clear, Insecticide or
mites bronze areas cigar-shaped miticide when
at tips of mites with a present.
needles or 10X hand lens Ref: Johnson and
twisted, or microscope. Lyon; Kelfer and
distorted On conifers, Smith
foliage or they are at
wiches’-broom. the base of
On hemlock, the needle or
entire plant under the needle
becomes sheath, except
chlorotic. on hemlock,
Many types of where they are
leaf or found on all
petiole parts of needle
galls on underside.
deciduous They are
plants. difficult to
detect.
Lace Leaves have Look for Don’t plant
bugs yellow to symptoms host plants
bronze throughout in full sun;
speckled season. apply
appearance insecticidal
with tar soap or
spots on registered
leaf undersides. insecticide
when nymphs
or adults
are active.
Ref: Johnson and
Lyon
Leafhoppers/ Stippled, Observation Registered
Planthoppers bleached, of the pest insecticide
or distorted or its cast when insects
foliage. skin in mid- are active.
and late Ref: Johnson
summer and Lyon
Thrips Stippled or Stippling Registered
bleached upper appears from insecticide
foliage or spring on, when insects
flowers, depending on are active.
often with region and Ref: Johnson
black frass thrips species. and Lyon.
on injured Examination of
areas. stippled areas
Stippling with a 10X
often seen hand lens
in rows. shows that
leaf tissue
has been
stripped away.
Ozone Large bronze Visual Replace
to brown observation with a
stippled of injury resistant
areas seen is related variety or
only on to a period species if
upper surface of poor air one is
of leaf. quality or available.
a temperature Ref: Sinclair
inversion. et al.
IDENTIFICATION AND BIOLOGY OF
TETRANYCHID MITES
The life cycle of tetranychid mites includes the following stages: egg, larvae,
nymph (up to several nymphal instars), and adults. In some species, males are
unknown and reproduction is believed to be parthenogenic (Johnson and Lyon 1988;
Weidhaas 1979). This means that females give rise to offspring without mating,
enabling rapid reproduction and population increases. Because of the large
number of generations in a single season, high infestations of mites can develop
rapidly (Huffaker et al. 1969; Johnson and Lyon 1988; Helle and Sabelis 1985;
Westcott 1973; Yepsen 1984). In general, mites deposit two to twenty eggs in a
single day, the exact number determined by environmental factors and the species
or strain involved. Silk production by mites varies from species to species,
with some producing copious amounts of silk, others little or none.
Habitats for the mite species in this module consist mainly of the foliage of
suitable host plants. Larvae and nymphs tend to feed on the underside of leaves,
while adults and older nymphs feed on both undersides and tops of leaves as well
as occasionally on buds and shoots.
Mites feed by rupturing leaf cells with a pair of needle-like stylets
(chelicerae) and inserting the mouth parts to draw up the cell contents while
the chelicerae are pushed deeper. Feeding causes small chlorotic spots to
appear, which eventually coalesce. Stippling occurs and large portions of the
leaf or the entire leaf becomes yellowed, bronzed, or whitened in appearance.
Leaf injury on evergreens may last for several seasons; injury on other plants
may cause premature leaf drop or may result in the death of the host plant.
Boxwood mite (Eurytetranychus buxi [Garman]). Adults are 1/32"
long, yellow green to reddish brown. Eggs are yellow, rounded, with flattened
ends. This species produces silk and is found throughout the United States on
boxwood, specifically varieties of American and European boxwood (Buxus
sempervirens). Japanese boxwood (B. microphylla) is rarely infested.
The boxwood mite eggs overwinter on the undersides of leaves and hatch in
mid-April. Early nymphs feed on undersides of leaves, second instar mites feed
on both sides of the leaf, and third instars move from leaf to leaf to feed.
Adults feed on shoots and upper surfaces of leaves. Populations are highest from
early spring to early summer, with a second peak in the fall.
Clover mite (Bryobia praetiosa [Koch]). Adults are brownish red to
red, 1/16" in length. Eggs are brick red, the nymphs red. These mites are easily
recognized under low magnification by their long front legs, which are over
twice as long as the other legs, and by the featherlike plates on the body. This
species does not produce silk, so the presence of webbing cannot be used as a
sign of this pest. Distributed throughout the United States on suitable host
plants, clover mites are also common indoors, frequently entering buildings in
large numbers in the fall.
Clover mite eggs overwinter in cracks in concrete foundations, between the
exterior and interior walls of buildings, and on the underside of the basal bark
of trees. These mites also overwinter as adult females or in other life stages.
Clover mites can become active at temperatures slightly above freezing. Eggs
hatch in late winter or early spring; one generation is usually complete before
mid-summer. Males of this species are unknown; reproduction is parthenogenetic
(Boudreaux 1963). Most eggs deposited by this generation aestivate until
September, but some hatch in early summer and produce several small successive
summer generations.
These mites feed on a wide variety of plants including clover, grasses,
dandelion, iris, ivy, mallow, strawberry, peas, tomato, violet, and zinnia. A
related species, the brown mite, feeds on tree foliage.
European red mite (Panonychus ulmi [Koch]). Adult mites are 1/32"
long and velvety red, with four rows of curved hairs on back arising from tan or
white humps (tubercles). Eggs and first instar nymphs are bright red; each egg
has a single central stalk or hair. Second and third instar nymphs are dull
green or brown. This species produces silk and thus webbing is seen at high
population levels. European red mites occur throughout the United States on
suitable host plants. They feed on apples and other fruits, nuts, and their
ornamental varieties. They may occasionally be found on elm, rose, mountain ash,
and a variety of other ornamental plants. European red mite overwinter as eggs
and hatch in early spring as new growth begins. Feeding activity and plant
injury occur throughout spring into early summer.
Southern red mite (Oligonychus illcis [McGregor]). Adult females
are 1/32" in length, blackish red, with backward curving spines. Adult males,
nymphs, and eggs are light red. This species produces silk. They are common in
the southeastern United States, New England, Ohio, and the Great Lakes states
but are particularly damaging in the deep south. Southern red mite feed on
broad-leaved evergreens, especially Japanese holly, Pyracantha, azalea,
and Camellia, as well as other hollies, laurel, and Rhododendron.
They overwinter as eggs on the foliage and twigs of their hosts. A cool weather
pest, Southern red mite develop damaging populations in early spring and late
fall. These mites thought to aestivate in the egg stage during summer, with
small populations becoming active during cool periods.
Spruce mite (Oligonychus ununguis [Jacobi]). Adults are 1/32" in
length with spines on the back, dark green or reddish green to nearly black with
tan legs. Eggs are reddish tan and nymphs greenish with tan legs. Spruce mites
produce copious webbing between needles of host plants. They are widely
distributed and may be found wherever suitable hosts occur. They attack only
conifers; primarily hemlock, spruce, arborvitae, Chamaecyparis, and
juniper. Fir and pine are attacked to a lesser extent. This mite overwinters as
eggs on the foliage and twigs of host plants. They are most active in cool
weather, so tend to increase in numbers and injury levels in early spring to
early summer, and again in the fall, while they may go into aestivation to avoid
hot, dry weather. Adults may be active in summer during cooler periods.
Twospotted mite (Tetranychus urticae ([Koch]). The common "spider
mite." Adults are large (1/8"), and yellowish with two or more predominant dark
spots on the back, which is sparsely covered with spines. These spots, which
become more apparent as each instar matures, are caused by accumulated food
material in the digestive tract. The eggs and nymphs are lemon yellow. They are
found throughout the United States, especially indoors and in greenhouses. There
are over 250 known host plants including flowers, foliage plants, corn and other
field crops, vegetables, brambles, and other herbaceous plants. They can be a
serious pest of roses, flowering fruits, and shrubs, and are frequently brought
outdoors on plants which were propagated or overwintered in the greenhouse. They
overwinter as eggs on host plants and cause damage to host plants throughout the
growing season. The warmer the temperature, the greater the rate of feeding and
reproduction. The twospotted mite becomes especially destructive during periods
of hot, dry weather, but also feeds and reproduces during cooler periods.
The twospotted mite can acquire several plant-infecting viruses during feeding
on infected hosts, but has not been shown to transmit them to new host plants
(Orlab 1968). Mites that enter houses can create a nuisance to homeowners and
can cause stains if they are crushed.
MONITORING AND THRESHOLDS FOR
TETRANYCHID MITES
Mite population cycles can be unpredictable, so timing of management practices
must be based on observations of the pest. Timing of monitoring for mites is
directly related to mite biology. For example, spruce mites may be active
anytime temperatures are over 50F, but once prolonged, hot, dry
weather occurs in summer they enter a type of dormancy known as aestivation and
generally do not become active again until fall. Aestivation occurs at about the
end of June in the mid-Atlantic region, when daytime temperatures are
consistently above 80F. Spruce mite aestivation corresponds to
the time when the activity level and generation times of other mite species,
such as the twospotted mite, the European red mite, and the southern red mite,
are increasing. Consult the information presented for each species as well as
the references for more detail on the population cycles of each mite species.
Mites are very small, so they must be knocked off the plants they are feeding on
to be counted. This is done by holding a piece of white paper or a clipboard
painted white under the plant and striking the branches with a rubber hose or
ruler. Generally the plant is struck three to five times before the mites are
counted. The number of times that this is done is not as important as doing it
the same number every time. Ten to fifteen seconds must pass before examining
the clipboard for mites, since it takes this long for them to begin moving after
being knocked off their host. Moving dots about the size of a period on this
page should be examined with a hand lens to determine that they are indeed mites
and to identify the species if possible. Population levels can be measured in a
variety of ways, including a simple presence/absence, ranges (e.g., 1-10, 11-20,
etc.), or actual population counts. In most cases, estimation of a population
range will suffice. Eggs tend to remain attached to the plant, so individual
branches must be examined to look for these. Again, estimating relative numbers
is more important than an absolute count. The number of eggs relative to the
number of adults will indicate if the population is increasing or decreasing.
Mite populations on plants that have cupped leaves, such as Japanese holly, also
need to be determined by examination of the individual plant, since mites tend
to remain in the cupped leaves when the plant is tapped.
Monitoring for mites is a time-consuming process. If you are willing to tolerate
some mite injury, the time required for monitoring can be reduced by focusing
monitoring efforts on plants in hot, dry areas, plants which have been under
heavy nitrogen fertilization, or plants which have had the most serious problems
in the past. If low mite populations are seen on these plants, then monitoring
of less susceptible plants can be skipped at that time. This is not
recommended if the aesthetic threshold of the plants being monitored is very low
(i.e. no injury can be tolerated).
Leaf discoloration and stippling caused by mite feeding can easily be confused
with several other insect and disease injury symptoms (refer to Table 1). It is
important not to assume that just because stippling is seen, mites are the
cause. Mites, eggs, or shed skins on leaf undersides will facilitate a
diagnosis. Stippling with tar-like frass on leaf undersides indicates lace bug;
lack of frass or mite signs is a clue that the injury is from air pollution.
Once mite activity is detected, a decision must be made as to whether
implementation of additional mite management tactics are warranted, and if so,
which is most appropriate. While a few action levels for mites have been
published (Hamlen et al. 1982; Nielsen 1989), it is unclear how these apply in a
generalized way. There is considerable evidence to show that host plant nutrient
status and drought stress (Jepsen et al. 1975; Mattson 1980) contribute to host
plant suitability as a food source for mites. This means that action thresholds
determined under one set of conditions may not be applicable in another system.
Published thresholds should be used as a guide, but to modified as the need
arises. The resource manager must keep accurate records of mite population
levels, plant injury symptoms, soil fertility, and rainfall at the individual
park. Relate these to timing and type of management strategies used in the past
to determine what works best at a particular site or on a certain plant species.
NON-CHEMICAL CONTROL OF TETRANYCHID
MITES
Good mite management combines regular monitoring to detect pest occurrence and
timely implementation of the most appropriate management tactics.
Monitoring is an essential part of a mite integrated pest management program
because injury cannot be seen until after feeding takes place and because mites
may be active any time microhabitat temperatures rise above 50F. This means that even though the ambient air temperatures are below 50F,
mites could be active on certain plants, such as those in sunny locations next
to a building.
Cultural Control
As was mentioned earlier, there is a considerable amount of evidence to
indicate that mite populations are higher on plants that have been under high
nitrogen fertilization regimes (Mattson 1980). Thus, plants that have mites
should not be heavily fertilized.
Physical Control
A strong, steady stream of water from a hose will wash mites from the
surface of some plant leaves. Prolonged (several hours) periods of heavy rain
have the same effect. This is only a temporary measure, most suited to an area
where no pesticides can be applied. Adult mites will generally return to the
plant within 24 hours.
Biological Control
A vast number of predators and pathogens have been examined for their potential
to serve as biological control agents for mites (Helle and Sabelis 1985). Some
are currently being successfully used, others show potential, while the
feasibility of others seems unlikely.
Mites in the family Phytoseiidae are important predators of plant-feeding mites
and have been used in biological programs for several pest species, particularly
in greenhouses. Spiders, beetles, flies, thrips, true bugs, and lacewings have
all been observed feeding on mites. Species in the lady beetle genus
Stethorus are voracious predators of mites and often eliminate infestations
of European red mite and spruce mite. However, the control often occurs after
the mite populations have peaked (Johnson and Lyon 1988). Tetranychid mites are
also susceptible to fungal and virus infections, but no pathogenic bacteria have
been reported as occurring in mites. There are no known insect parasitoids of
mites (Helle and Sabelis 1985).
Predaceous mites have been used in greenhouses to control twospotted and other
mite pests with good results. Predatory mites are available from commercial
suppliers. See Anonymous 1991 for a list of sources. Some commonly used
predatory mites include the following.
Phytoseiulus persimilis is a predatory mite used primarily in
Europe to control mite pests of greenhouse-grown tomatoes, cucumbers, and sweet
peppers. It must be released periodically at carefully timed intervals for
optimal control. It is used infrequently on greenhouse-grown ornamentals due to
lower damage tolerance levels and lack of resistance to pesticides (Field and
Hoy 1984).
Insecticidal soap is toxic to the adult predatory mite at rates needed to obtain
satisfactory phytophagous mite control. Insecticidal soap can be applied three
days after predator release without significantly reducing control, apparently
because it does not cause significant egg mortality (Osborne and Petitt 1985). A
recent study of the effect of abamectin (a pesticide derived from a bacterial
toxin) on this mite and the pest mite, Tetranychus urticae, demonstrated
that abamectin will reduce the population of both, with a greater reduction in
the population of the pest mite species than in the predatory mite. Thus it
could be used in an integrated pest management program to reduce the
predator/prey ratio and increase the effectiveness of Phytoseiulus persimilis
as a predator (Zhang and Sanderson 1990).
Phytoseiulus macropilis, a related predatory mite, was found by
Hamlen and Poole (1982) to give acceptable control on twospotted mite on
greenhouse-grown Diffenbachia when applied at a ratio of 1:10 or lower and
reintroduced every eight weeks. As with P. persimilis, predators must be
introduced into low-density spider mite populations (Samlen and Lindquist 1981).
Mataseiulus (Typholdromus) occidentalis is a
predatory mite that has been developed into several strains, one of which is
resistant to most organophosphate insecticides and to carbaryl. Another strain
does not go into dormancy under low light or short photoperiod conditions. These
strains are preferred in that they can prey upon twospotted-mites throughout the
year in greenhouses. M. occidentalis is preferred for mite control for
ornamentals and long-term crops (such as roses grown for cut flowers) because it
gives long-term control from a single release. This predator is unlikely to
bring about full control without leaf damage caused by the pest mite; therefore,
application of selective acaricides are useful in an integrated program (Field
and Hoy 1984). Field and Hoy (1986) suggest that although this species does not
give as good control of twospotted mite as does P. persimilis, it would
be a better choice as a biological control agent in long-term crops on which
pesticides will be used. They suggest that P. persimilis would be a
better predator for twospotted mite on short-term crops that are grown with
minimal pesticide inputs. For current information on pesticide resistance in
M. occidentalis, see Hoy and Conley (1987).
CHEMICAL CONTROL OF TETRANYCHID MITES
Recent advances in the development of horticultural oils have made this the
first pesticide to consider in the management of mites (Baxendale and Johnson
1988; Baxendale and Johnson 1989; Davidson 1990; Davidson et al. 1990; Grossman
1990). New oil formulations do not have the problems of phytotoxicity that were
so common among older formulations. Their effective control of mite populations
with minimal impact on beneficials make them well-suited to an integrated pest
management program. A drawback to the use of oils is the necessity of contacting
the pest to be killed. Thus oils tend to give unsatisfactory control in dense
plantings, on leaves that are cupped (e.g., Ilex crenata `Convexa'), or
on plants that are in hard-to-reach areas. In these instances, pesticides with
some residual activity could be used. Consult your regional Integrated Pest
Management coordinator concerning the best choice of pesticide for your
situation.
IDENTIFICATION AND BIOLOGY
OF ERIOPHYID MITES
Eriophyid mites are a diverse family of arthropods, containing many species with
a wide range of plant hosts and biologies. They can be divided into three
categories based on the type of plant injury they cause: galls, twisted,
distorted foliage and chlorotic, stunted growth. The gall makers are rarely
detrimental to plant health, but are a concern among the public because they are
so obvious. In general, the mites that cause these galls overwinter as adults
and begin feeding on expanding leaves in the spring. This induces formation of a
gall which surrounds the mite as it feeds. Eggs are laid within the gall; nymphs
mature within the gall and the emerging adults infest new foliage.
The eriophyid mites that injure foliage have varied life cycles. They are a more
serious concern than the gall-makers because they can cause distortion and
dieback of plant tissue. Consult Johnson and Lyon (1988) and Keifer et al.
(1982) for more information on eriophyid mite life cycles.
MONITORING AND THRESHOLDS FOR ERIOPHYID MITES
Eriophyid mites are often overlooked because they are so difficult to see and
because the injury they cause (especially necrosis and dieback) can be
attributed to many other causes. Thus, the first part of developing a management
strategy for eriophyid mites is the education of plant monitors about this
mite's biology and preferred hosts and the injury it causes. Monitors should
realize that they will most likely not see eriophyid mites without a microscope,
and that they may need to submit a sample to the Cooperative Extension Service
for identification.
It is difficult to outline a monitoring program for these mites because the life
cycles vary so much depending on the species. In general, monitors should be
aware of the types of injury caused by eriophyid mites, and that the mites will
be difficult to observe. In conifers, this is complicated by the fact that these
mites often feed below the needle sheaths.
CONTROL OF ERIOPHYID MITES
In the case of the gall-making eriophyid mites, no intervention is warranted.
Three cases where intervention often is appropriate is on hemlock, privet, and
white pine, where these mites can cause considerable injury. In these cases, an
insecticide such as acephate is usually recommended (Davidson et al. 1990;
Keifer et al. 1982; Smith 1990), since they seem to give better control than oil
or other miticides.
There have been many observations of predatory mites occurring in conjunction
with eriophyids, but their role in population regulation is unknown (Johnson and
Lyon 1988).
REFERENCES
1. Anonymous. 1967. Controlling clover mites around the home. U.S.
Department of Agriculture - Agricultural Research Service, Washington, D.C. Home
and Garden Bull. 134.
2. Anonymous. 1991. Directory of producers of natural enemies of common
pests. IPM Practitioner 8(4): 15-19.
3. Baxendale, R.W., and W.T. Johnson. 1988. Evaluation of summer oil
spray on amenity plants. Jour. of Arboric. 14(9): 220-225.
4. Baxendale, R.W., and W.T. Johnson. 1989. Update note concerning
horticultural oil concentrations for verdant use. Jour. of Arboric. 15(2):
51-52.
5. Boudreaux, H.B. 1963. Biological aspects of some phytophagous mites.
Ann. Rev. Entomol. 8:137-154.
6. Davidson, J.A. 1990. Recommendations for Insect Monitoring and
Control: Trees and Shrubs. University of Maryland Cooperative Extension Service,
Bulletin 258.
7. Davidson, J.A., S.A. Gill, and M.J. Raupp. 1990. Foliar and growth
effects of repetitive summer horticultural oil sprays on trees and shrubs under
drought stress. Jour. of Arboric. 16(4):77-81.
8. Field, R.P., and M.A. Hoy. 1984. Biological control of spider mites on
greenhouse roses. Calif. Agric. March/April pp. 29-32.
9. Field, R.P., and M.A. Hoy. 1986. Evaluation of genetically improved
strains of Metaseiulus occidentalis (Nesbitt) (Acarina:Phytoseiidae) for
integrated control of spider mites on roses in greenhouses. Hilgardia
54(2):1-31. 1986.
10. Green, S.G. 1982. Mites. pp. 739-775. In Mallis, A. (ed.)
Handbook of Pest Control, 6th ed. Franzak and Foster Co., Cleveland, OH.
11. Grossman, J. 1990. Horticultural oils: New summer uses on ornamental
plant pests. IPM Practitioner 12(8):1-10.
12. Hackett, K., and A.E. Giraldi. 1982. IPM binder for azalea lace bug.
John Muir Inst. Napa, CA.
13. Hamlen, R.A., and R.K. Lindquist. 1981. Comparison of two
Phytoseiulus species as predators of twospotted spider mites on greenhouse
ornamentals. Environ. Entomol. 10: 524-527.
14. Hamlen, R.A., and R.T. Poole. 1982. Integrated pest management of
spider mites. Southern Florist and Nurseryman. Jan. 8, 1982. pp. 27-29.
15. Herbert, H.J. 1981. Biology, life tables, and intrinsic rate of
increase of the European red mite, Panonychus ulmi (Acrina:
Tetranychidae). Can. Entomol. 113:65-71.
16. Huffaker, C.B., M. van de Vrie, and J.A. McMurtry. 1969. The ecology
of tetranychid mites and their natural control. Ann. Rev. Entomol. 14:125-174.
17. Jepsen, L.E., H.H. Keifer, and E.W. Baker. 1975. Mites Injurious to
Economic Plants. University of California Press, Berkeley.
18. Johnson, W.T., and H.H. Lyon. 1988. Insects That Feed on Trees and
Shrubs. Comstock Publishing Assoc., Ithaca, N.Y.
19. Keifer, H.H., E.W. Baker, T. Kono, M. Delfindo, and W.E. Styer. 1982.
An Illustrated Guide to Plant Abnormalities Caused by Eriophyid Mites in North
America. USDA Handbook 573.
20. Helle, W., and M.W. Sabelis, eds. 1985. Spider mites: Their Biology,
Natural Enemies and Control. Vol. 1B. Elsevier Scientific Publishers, New York.
21. Hoy, M.A., and J. Conley. 1987. Toxicity of pesticides to western
predatory mite. California Agriculture July/August 1987 pp. 12-14.
22. Mague, D.L., and H.T. Streu. 1980. Life history and seasonal
population growth of Oligonychus ililis infesting Japanese holly in New Jersey.
Environ. Entomol. 9(4).420-424.
23. Mattson, W.J., Jr. 1980. Herbivory in relation to plant nitrogen
content. Ann. Rev. Ecol. and Syst. 11:119-161.
24. Nielsen, D.G. 1989. Integrated pest management in arboriculture: from
theory to practice. Jour. of Arboric. 15(2): 25-30.
25. Nielsen, D.G. 1990. Evaluation of biorational pesticides for use in
arboriculture. Jrnl. of Arboric. 16: 82-83.
26. Olkowski, W., H. Olkowski, and T. Javits. 1979. The Integral Urban
House. Sierra Club Books, San Francisco, CA.
27. Orlob, G.B. 1968. Relationships between Tetranychus urticae
Koch and some plant viruses. Virology. 35:121-133.
28. Osborne, L.S. 1984. Soap sprays: an alternative to a conventional
Acaricide for controlling the twospotted spider mite (Acari: Tetranychidae) in
greenhouses. J. Econ. Entomol. 77(3):734-737.
29. Osborne, L.S., and F.L. Petitt. 1985. Insecticidal soap and the
predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae), used in
management of the twospotted spider mite (Acari: Tetranychidae) on greenhouse
grown foliage plants. J. Econ. Entomol. 78: 687-691.
30. Schwartz, P.H. 1982. Guidelines for the control of insect and mite
pests on foods, fibers, feeds, ornamental, livestock, and households. U.S.
Department of Agriculture - Agricultural Research Service, Washington, D.C. USDA
ARS Handbook 584.
31. Sinclair, W.A., H.H. Lyon, and W.T. Johnson. 1987. Diseases of Trees
and Shrubs. Cornell Univ. Press, Ithaca, NY.
32. Smith, S.L. 1990. Chemical briefing. American Nurseryman
172(4):62-74.
33. Weidhaas, J.A. 1979. Spider mites and other Acarina on trees and
shrubs. Jrnl. of Arboric. 5(1):9-15.
34. Westcott, C. 1973. The Gardener's Bug Book, 4th edition. Doubleday and Co.,
N.Y.
35. Yepsen, R.B. (ed.) 1984. The Encyclopedia of Natural Insect and
Disease Control. Rodale Press, Emmaus, PA.
36. Zhang, Z., and J.P. Sanderson. 1990. Relative toxicity of abamectin
to the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae) and
twospotted spider mite (Acari: Tetranychidae). J. Econ. Entomol. 83(5):
1783-1790.
|
![[Company Logo Image]](_borders/avms.gif)
AVMS 
