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Aphidoletes aphidimyza Aphid Predatory Midge by Applied BioNomics PO Box 1555, Ventura, CA 93002800-248-2847 * 805-643-5407 * fax 805-643-6267 question
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Target pest
Aphids, all types, to some extent potato (tomato,
pepper) psyllid
Description
‘Aphidoletes’ larvae are
voracious native predators of over 60 species of aphids.
·
Larvae are
orange, legless maggots, up to 3 mm (1/16 inch) long.
·
Adults are
small, delicate midges (flies) 2-3 mm (1/16 inch) long, with long legs. Adults
are rarely seen as they are mostly active in the evening.
·
Rincon-Vitova’s
Max Line of Aphidoletes are collected and shipped with minimum time in transit
and no holding under refrigeration to assure adults with the ability to fly
long distances to find aphids.
Use in Biological Control
·
Aphidoletes
are used to control aphids indoors in commercial greenhouses and interior
plantscapes as well as outdoors in orchards, shade trees, roses and home
gardens.
·
Optimum
conditions are 21-25º C (70-77º F) and high relative humidity (over 70%),
particularly for the pupal stage, which must not dry out.
·
If aphids are present in outdoor plants in late summer, a release of
Aphidoletes at this time helps reduce the overwintering aphid population, while
establishing an overwintering predator population that will be active early the
following spring.
·
A feature of Aphidoletes in production greenhouses is its habit of
flicking the aphid off the foliage or flowers leaving no sign on the plant.
Monitoring Tips
Using 10-15 X hand lens, full grown larvae are
relatively easy to see among the aphids because of their characteristic orange
color. Younger larvae are much smaller
and pale in color, difficult to see.
A complete life cycle takes 21 days at 21º C (70º F).
Development rate depends on temperature and availability of prey.
·
Sex ratio in populations vary, but there are usually somewhat more
females (60% females).
·
Female midges lay their eggs on leaves beside aphids. Each females lays
150-200 eggs during her lifespan of 1-2 weeks. The eggs are shiny orange ovals,
less than 0.3 mm (1/50 inch) long.
·
At 21ºC, eggs hatch in 2-3 days and the tiny, legless larvae crawl along
the leaf in search of aphids.
·
Larvae feed by biting aphids and paralyzing them with a toxin before
sucking out the aphid body fluids. They feed for 7-10 days and can kill 3-50
aphids per day. Where aphid populations are high, larvae kill many more aphids
than they can consume.
·
To pupate, larvae drop to the ground and burrow into the top 1-2 cm (1/2
inch) of soil or organic material to spin a cocoon. Adults emerge in 2-3 weeks.
·
Outdoors, the last generation of Aphidoletes in the fall overwinters in
the cocoons in the soil. They are very hardy and survive outside throughout the
growing regions of Canada.
Aphidoletes is sent as
pupae (cocoons) in moist vermiculite or sand. The predators may be released in
either of two ways:
·
Immediately
upon receipt, gently sprinkle the vermiculite carrying the cocoons onto the
surface of the soil or growth media, in the shade; keep the vermiculite moist
(not wet) until adults have emerged.
·
Hold
containers at 22ºC (70ºF) temperature checking daily for emergence until adults
are seen flying in the container, then place the container with the corner cut
open in the shade, greenhouse or garden, ideally at dusk.
·
Adults
should begin to emerge within 7-10 days and all should emerge within 14 days of
receipt.
Note: Aphidoletes
larvae respond to cool temperatures and shortening day lengths (less than 16
hrs) by entering diapause (like a hibernation state). There has been hesitation
in the past to use them between September and mid-March. However new
observations suggest a great value from low year-round releases in greenhouses
to keep the pressure on low levels of aphids (see below).
Generally, Aphidoletes
should be released in the spring, 2 or 3 times at 7-10 day intervals to
establish the predator.
Greenhouse Vegetables
·
Tomato – 1 Aphidoletes/6 plants, weekly for 2 weeks
·
Pepper – 1 Aphidoletes/plant, weekly or until established
·
Cucumber – 10 Aphidoletes/plant, weekly in infested areas only until
established
Outdoor Use
·
Gardens – 250 Aphidoletes/aphid hot spot, weekly for 2 weeks
·
Orchards – 5-10 Aphidoletes/tree, weekly for 3 weeks
·
Shade trees/5-10 Aphidoletes/tree, weekly for 3 weeks
·
Roses –
3-5 Aphidoletes/plant, weekly for 3 weeks
For large areas, such as
apple orchards, use 2,000-8,000 Aphidoletes/ha (1,000-4,000/acre), repeated 1-3
times, 1-2 weeks apart, or until established.
For outdoor use, release
during the evening on the upwind side of the planting so that the prevailing
winds will help to disperse the midges throughout the plot.
For Best Results
Using Pesticides
For effects of specific
pesticides on Aphidoletes.
For additional control of
aphids, pirimicarb (i.e., Pirliss®) may be used. It is slightly toxic to
Aphidoletes, but the repellent effect of the pesticide disperses the aphids and
has been found to repel Aphidoletes females from laying eggs on leaves with
pirimicarb residues therefore avoid frequent use. Insecticidal soaps are
harmful to all stages of Aphidoletes, but have no residual effect.