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Description
The sweetpotato whitefly (SPWF) adult is approximately 1/16 in.
long with a yellow cast. The two pairs of wings are folded at an
angle of 45 degrees over the back and are narrower than the greenhouse
whitefly (GHWF). Like other whiteflies, adults are quite active
and are commonly found feeding on the lower leaf surfaces. The eggs
are cigar-shaped, creamy white when young turning to a light brown
before hatching. The nymphs are flat and oval shaped and white to
gold in color. The pupa or fourth nymphal stage is rounded and pointed
with no parallel sides. It also lacks the ring of setae as is seen
with the greenhouse whitefly pupa, but usually has several pairs
of filaments rising from its upper surface. These filaments are
generally shorter as as compared to those found on the GHWF. |
Click
on image for larger version
Figure 1. Sweetpotato Whitefly Adult on Hibiscus
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Life
History
The lifecycle of the SPWF is similar to the GHWF. Egg laying begins
approximately 7 days after emergence with the eggs laid singly or
in groups as with the GHWF. Approximately 12 days later, the first
instar nymphs emerge, move about 1/8 inch and then settle down.
They undergo three molts with each stage lasting for 6 - 8 days.
The fourth instar or pupa lasts approximately 6 days with the adult
emerging in the morning. The entire lifecycle takes about 39 days
at 65° - 75°C, approximately 1 week longer than the GHWF.
Optimum temperature for development is 80°C. The SPWF is unable
to overwinter outdoors in northern regions, but may have continuous
and/or overlapping generation in the greenhouse.
Damage
As with other whiteflies, the SPWF reduces plant growth and vitality
and in some cases may cause plant death. In addition, extensive
feeding produces large quantities of honeydew which promotes the
growth of sooty mold and a reduction in photosynthesis. Most important,
the SPWF is known to vector several diseases of field crops and
may be a vector of Gemini visues.
Nonchemical
Control
Similar to the greenhouse whitefly.
Chemical
Control
Similar to the greenhouse whitefly.
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