|
| Technical Bulletins- Encarsia formosa |
 |
|
 |
Encarsia formosa
Whitefly Exterminator II
Target Pests:
Greenhouse whitefly (Trialeurodes vaporariorum); Silverleaf whitefly (Bemesia
argentifolia);
Sweet potato whitefly (Bemesia tabaci).
Description:
Encarsia formosa is a tiny parasitic wasp that parasitizes whiteflies.
It was the first biological control agent developed for use in greenhouses.
Adults are black with yellow abdomen, less than 1 mm (1/20 inch) long (they
do not sting). Larval stages live entirely inside immature whiteflies,
which darken and turn black as the parasites develop inside.
Use as Biological Control:
Encarsia are used to control greenhouse whitefly on greenhouse cucumbers,
tomatoes, peppers and poinsettias and other plants grown in greenhouses.
They control silverleaf/sweet potato whitefly using high release rates.
Optimum conditions are temperatures over 20°C (68°F) and relative
humidity 50-70%. When daytime temperatures are less than 18°C (64°F).
Encarsia activity is sharply reduced, making them less effective. Encarsia
should not be used if high whitefly populations are already established.
The predatory beetle Delphastus avoids feeding on whiteflies parasitized
by Encarsia, therefore it can be used with Encarsia. The parasitic wasp
Eretmocerus californicus may also be used with Encarsia.
Monitoring Tips:
Check the undersides of lower leaves for parasitized whitefly scales. They
turn black (for greenhouse whitefly) or transparent brown (for sweet potato
whitefly) so are easy to tell from unparasitized scales, which are whitish.
Life Cycle:
The complete life cycle takes about 28 days at 21°C (70°F). Temperature
affects developmental rate; for example, larval development takes 15 days
at 25°C (77°F) and 45 days at 15°C (59°F). Encarsia populations
are all female (males sometimes occur but they are not functional). Eggs
are laid in 2-week-old whitefly scales (second and third whitefly larval
stages), one egg per whitefly. Most Encarsia are female and each lays up
10 eggs per day for an average of 200 eggs. Larvae develop inside the whitefly
scale for 10 days (at 20° - 25°C). They pupate for another 10 days,
then adults emerge by chewing a hole in the top of the scale. Adults are
most active for about 10 days, although they can live up to 30 days.
In addition to parasitizing them, Encarsia kill whitefly scales by feeding
on the host directly; they also feed on whitefly honeydew.
Product Information:
Encarsia pupae are sold glued onto cards. It is important to hang the cards
from lower leaves in the shade as Encarsia tend to fly upward; avoid wetting
them while watering. If there are hanging baskets some cards must be placed
on the baskets, as well as on infected plants.
Adults will emerge from the pupae over a period of 1-2 weeks at 20° -25°C.
Small emergence holes in the pupae are visible using a 5-10X lens and indicate
that the parasite has emerged.
If necessary, the Encarsia pupae can be held for up to 2 weeks at 5°-10°C
(40°-50°F), however the percentage of emergence will decrease with
time.
Introduction Rates:
1-10 Encarsia/m? (10 ft?) or 1-5 Encarsia/infested plant, every 1-2 weeks,
until 80% of whitefly scales are parasitized. Encarsia are usually released
in low numbers before pests are present (called an inoculative release),
or, in higher numbers after pest populations are established (called an
inundative release).
Above rates must be at least doubled for control of silverleaf/sweet potato
whitefly or if temperatures are 18?C or less.
Encarsia tend to remain in regions where the whitefly are concentrated,
therefore it is important to distribute them well:
For inoculative releases - spread introductions over 40
or more release points per 1,000 m sq.
For inundative releases - use 60 or more release points per 1,000 m sq.
and place more where whiteflies are found.
Once the percentage of parasitized scales exceeds 80%, the number of Encarsia
present should be enough to control whitefly.
For Best Results:
The whitefly species in a crop must be correctly identified to make sure
it is a species that Encarsia can control and to determine the correct
release rate. Eliminate whitefly from alternate plant sources, such as
weeds or previous crops, and from cuttings before Encarsia
releases begin.
High whitefly populations hinder movement of the parasite as does the presence
of excessive amount of honeydew. Remove whiteflies and honeydew by spraying
with water or 1% Safer's insecticidal soap.
When de-leafing plants, do not remove leaves that have significant numbers
of black (parasitized) whitefly scales. If leaves must be pruned from plants,
retain them, under the plants, until the wasps have emerged (1 to 2 weeks).
Using Pesticides:
Encarsia are extremely sensitive to insecticide residues. Plastic covering
or flooring used in greenhouses may harbor residues at levels that are
harmful to this parasite for over 6 months.
Spreader stickers in spray applications are harmful to Encarsia.
If whitefly hot spots develop, spot spray with Safer's soap (1% solution),
weekly, directing the spray onto new leaves to kill adult whiteflies and
early stages of scale. Kinoprene (Enstar) may also be used on ornamental
crops. |
|
|
|
|
|
|
| 0 items |
|
|
|
 |
Bestsellers |
|
|
|
Information |
|
|
|
