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Chaetanaphothrips signipennis |
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Banana Rust Thrips |
Hosts | Distribution | Damage | Biology | Behavior | Management | Reference |
Authors
Arnold H. Hara, Extension Entomologist; Ronald F.L. Mau, Entomologist; Christopher M. Jacobsen, Research Associate; Ruth Y. Niino-DuPonte, Research Associate
Department of Plant and Environmental Protection Sciences
and
Ronald Heu, Entomologist.
Hawaii Department of Agriculture
Honolulu, Hawaii
INTRODUCTION
Banana rust thrips, Chaetanaphothrips signipennis (Bagnall)
(Thysanoptera: Thripidae), was collected once in 1954 from an outdoor planting of
anthuriums in Manoa, O`ahu, and was not seen again until 1996, when it was collected from
several commercial nurseries and farms on the island of Hawaii, after causing severe
damage to anthurmium, ti, dracaena, and banana.
The primary hosts of banana rust thrips are anthurium, ti, dracaena, and banana. They also infest immature fruits of orange, tangerine (mandarin), and tomato, as well as green beans.
Banana rust thrips are present in parts of Australia (Queensland and New South Wales) and Central America (Honduras, Panama), Brazil, Fiji, Sri Lanka, and India. In the US, they are also established in Florida and Hawaii.
The primary hosts of banana rust thrips are anthurium, ti, dracaena, and banana. They also infest immature fruits of orange, mandarin (tangerine), and tomatoes, as well as green beans.
The appearance of feeding damage
caused by banana rust thrips varies with host plant species. In most cases, thrips prefer to feed on very
young, succulent, immature fruits, flowers, and foliage.
On anthurium, banana rust thrips damage
appears as white streaks or scarring on the front and back of the spathe, deformed
spathes, and, with age, bronzing of injured
tissue (Figure 1c). In severe cases, mature
anthurium spathes fail to open, reduced plant growth may occur, and the foliage may be
affected by deformity, bronzing and streaking. Damage
by banana rust thrips to certain anthurium cultivars, such as Kalapana and
Ozaki, may appear as curly-cues rather than streaks.
On banana, feeding damage is observed
on the pseudostem, but it is the injury to the fruit that significantly affects
marketability (Figure 2). Thrips feeding in
leaf sheaths results in characteristic dark, V-shaped marks to the outer surface of leaf
petioles. Damaged tissue becomes bronze or
rust-colored with age. Feeding damage to the
fruit occurs on fingers soon after flower petals dry, typified initially by a water-soaked
appearance. Young fruits may exhibit dark,
smoky-colored random squiggles or curly-cue feeding tracks on the surface. On mature fruit, oval-shaped, reddish
stains may be seen where the fingers touch.
Extensive damage may cover more of the fruit surface with reddish-brown or black
discoloration and superficial cracks. Though unmarketable, such fruits are still edible.
Figure 1.Feeding damage by banana rust thrips on ti and anthurium. a) streaks and curly-cue markings on opened ti leaf. b) deformed leaf whorls on red ti that failed to unfurl; c) deformed anthurium spathe. [Photos: A.H. Hara]
Figure 2. Damage to banana fruit by banana rust thrips [Photo: A. H. Hara]
Adult banana rust thrips reproduce sexually. The entire life cycle (egg to adult, Figure 3) of banana rust thrips is completed in approximately 28 days but may take up to 3 months during the cooler season.
Figure 3. Life cycle of the banana rust thrips. [Insect drawings from D. Schulz ~1950]
After mating, females lay kidney-shaped eggs that are invisible to the naked eye by depositing them in plant tissue where the thrips feed. Eggs hatch into nymphs in 6 to 9 days.
The newly hatched yellow nymphs feed for a few days before molting into the second nymphal stage, which is yellow or orange and feeds for a few more days. After 8 to 10 days, mature nymphs migrate off the host plant into soil or growth medium below and molt into prepupae.
PREPUAE AND PUPAE
Prepupae look similar to nymphs but have wing pads. After 2 to 5 days, prepupae enter the pupal stage, which has longer wing pads. Both stages remain in the soil, medium or debris beneath the host plant and are capable of crawling but do not feed.
In 6 to 10 days, the adult
emerges from the pupal cell and may remain beneath the surface for up to 24 hours before
making its way up to reinfest the host plant.
Adult female banana rust
thrips are slender, creamy yellow to golden brown, and 1/16 to 1/25 inch (about the
thickness of a dime) (Figure 4). Their wings
have dark eye-like spots at the base and are fringed; when the wings are folded, the adult
appears to have a black line down its back.
Figure 4. Adult banana rust thrips [Photo: C.A. O'Donnell, UC Davis]
Higher temperature and humidity and new growth of host plants appear to be favorable to thrips feeding and breeding, leading to heavier infestations and damage during the summer months. Thrips prefer to feed on young, growing plant tissue, such as areas of bud development, or in anthurium, the base of the plant where the spathes develop.
NON-CHEMICAL CONTROL
Biological
In Hawai`i, anthocorid bugs
(Orius tristicolor, O. persequens, and O. insidiosus) are general thrips predators, but the extent
of their effectiveness against banana rust thrips is not known. Some lacewings, ladybird beetles, and predacious
mites may also exert some control on nymph and adult thrips, while ants may prey on
prepupae and pupae in the soil, medium or surface debris near the base of the host plant. Several fungi, including Paecilomyces spp. and Verticillium lecanii, have been isolated from other
thrips species and may infect banana rust thrips as well.
Cultural
Remove infested flowers and
foliage from the field or shadehouse to eliminate sources of thrips. Discard old stock plants that may harbor thrips,
and obtain thrips-free propagative material for restocking.
There are no reports of
resistant or susceptible anthurium cultivars, although injury is more noticeable on pastel
shaded cultivars such as Marian Seefurth.
In banana plantings, covering bunches with polyethylene bags during fruit development provides a physical barrier to insect infestations; but bags cannot fully protect the fruit when a thrips infestation is heavy.
Biorational
A hot water dip at 120o
F (49o C) for 10 minutes before planting can disinfest anthurium propagative
material of banana rust thrips. Banana,
dracaena, ti and anthurium have all shown
potential for heat treatment, although cultivar sensitivity has been observed to vary with
season. Tests indicated that some anthurium
cultivars tolerate hot water treatment as top cuttings with leaves, including: White
Lady, Blushing Bride, and Kozohara, while Ozaki
cultivar cannot tolerate hot water dip except as whole stem pieces (gobo). The
dracaena cultivar Janet Craig was also tolerant of hot-water treatment. Due to variations among cultivars and growing
conditions, small-scale phytotoxicity tests should be conducted before a large amount of
propagative material is hot-water treated.
CHEMICAL CONTROL
Because pesticide registrations may
change, consult a chemical sales representative, the Hawaii Department of Agriculture, or
the CTAHR Cooperative Extension Service for information on insecticides currently approved
for use against thrips in a particular crop.
Remove infested flowers and foliage
from the field or shadehouse to allow increased insecticide penetration and coverage. Growers have reported that banana rust thrips
tends to be more difficult to control than anthurium thrips, possibly due to the
formers pesticide tolerance and greater reproductive capacity. Growers are advised to consider insect
development of pesticide resistance in devising their integrated pest management
practices.
Generally, thrips populations
increase during the summer and decrease during the winter due to fluctuations in
temperature and rainfall. Consequently,
repeated spray applications may be needed only from May through August. Foliar sprays are usually applied two to three
times at 2-week intervals for moderate to severe thrips infestations. Since thrips prefer
young, growing plant tissue, direct insecticide sprays to the area of bud development, or
in anthurium, to the base of the plant where the spathes develop. Use caution when applying insecticides on
anthurium, becauses phytotoxicity varies among cultivars and is more likely to occur under
hot, dry growing conditions. When thrips
injury is sutained during the bud stage, injured flowers will be harvested for at least
one month following application of an effective insecticide.
In banana, spraying the immature
bunches and the surrounding soil can significantly reduce thrips damage to the fruit; when
bagging bunches, spray just before bagging. A
contact granular insecticide applied in a 30-inch radius around each banana plant is
effective against the prepupal and pupal stages of banana rust thrips that inhabit the
soil. No granular insecticide is currently
registered for use on anthuriums.
FOLLOW SAFETY PRECAUTIONS GIVEN ON MANUFACTURERS LABELS.)
PRECAUTIONARY STATEMENT
Consult a chemical sales representative, the Hawaii Department of Agriculture, or the University of Hawaii Cooperative Extension Service for correct formulation of insecticides, more information, or updated recommendations. The user is responsible for the proper use, application, storage, and disposal of pesticides.
DISCLAIMER
Reference to a product does not imply approval or recommendation by the College of Tropical Agriculture and Human Resources, Cooperative Extension Service, University of Hawaii, or the United States Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable. All materials should be used in accordance with label instructions.
This information is the culmination of a series of interviews with researchers, extension agents, chemical sales representatives, and growers in Hawaii and a worldwide literature search.
FOR QUESTIONS OR COMMENTS PLEASE CONTACT:
Arnold Hara: 461 West Lanikaula St. Hilo, HI 96720, Ph: (808) 974-4105 Fax: (808) 974-4110 E-mail: arnold@hawaii.edu
Caldwell, N.E.H. 1938. The Control of Banana Rust Thrips.
Department of Agriculture and Stock. Division of Plant Industry (Research), Bulletin #16,
December 1938.
Denmark, H.A. and L.S. Osborne. 1985. Chaetanaphothrips
signipennis (Bagnall) in Florida (Thysanoptera: Thripidae). Ento. Circular No. 274,
Sept. 1985, Florida Department of Agriculture and ConsuemrService, Division of Plant
Industry.
Lewis, T. (Ed.) 1997. Thrips as Crop Pests. Institute of Arable Crop Research, Rothamsted,
Harpenden, Hertfordshire, CABI Publishing, UK.
DEC/2002
Adapted from the authors' CTAHR PIO publication, "Banana Rust Trhips Damage to Banana and Ornamentals in Hawaii". Insect Pests IP-10, June 2002.
BR-THRIPS