| Several insect pests of noni were
observed at the Bird Sanctuary on the island of Rota in the
Northern Marianas islands of Micronesia in 2002. Some of the
damage we observed was significant. The Bird Sanctuary is a
protected habitat that is not really managed, and the noni population
there is a wild population that hosts a thriving community of
insects, both plant-parasitic and beneficial. |
| PLANT-PARASITIC INSECTS |
- Loopers and cushiony scale
- Weevils and rose beetles
- Stem-boring moth/Lepidoptera
- Leaf miners
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1.
LOOPERS (and cushiony scale)
Noni leaves in Rota may be attacked by green caterpillars known
as loopers. The pest in question on Rota is probably the green
garden looper. |
Looper feeding injury. The green garden looper
prefers to feed at noni leaf margins, leaving severely diminished
leaves with irregular margins. For some leaves, almost all leaf
tissue is gone, leaving only the primary veins. The white objects
on the leaves in the photograph are scale insects (one of the
cushiony scale species). |
Young looper on stem. Can you find the young,
yellowish-green looper in this image? It is on the noni stem,
near point of attachment of the leaf petioles. They can grow
to be much larger than this well-camouflaged young caterpillar.
|
Looper damage. Marginal chewing damage on noni
leaf (center) associated with loopers. A brown leaf spot symptom,
perhaps a fungal disease or leaf injury, is visible at upper
right. |
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2. WEEVILS AND BEETLES
In the Bird Sanctuary on Rota, noni leaves with numerous small,
irregular holes were observed. We believe these holes are the
result of feeding by weevils on noni foliage, and/or rose beetles.
The weevil and rose beetle populations in the area were quite
large. |
An irregular shot hole pattern is associated with insect feeding,
perhaps weevils or rose beetles. |
Windowing effect on affected noni leaf associated
with noni weevils (adaxial leaf surface). |
Windowing effect on affected noni leaf associated
with noni weevils (abaxial leaf surface). |
Mature weevil associated with foliar damage to noni. (species
undetermined) |
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3. STEM-BORING MOTH
A severe twig and stem dieback symptom was observed at the Bird
Sanctuary in Rota. The damage is associated with an insect,
a Lepidopteran larvae, probably a moth that lays its eggs at
the tips of stems, twigs and branches, or fruits. When the eggs
hatch, they feed within stems tissues, hollowing out the noni
stems and killing that part or the branch or organ. |
Twig and branch dieback after the moth larvae hatched and fed
within the growth tip of the stem. |
Blackened insect frass (excrement) at the apical meristem of
a noni stem. Moth larvae are inside the stem, devouring the
soft tissues of the inner noni stem. Adult female moths lay
their eggs in the apical meristem region of vertical stems and
lateral braches, as well as in noni fruit. |
Noni stem dissected to reveal the blackened inner stem tissues
caused by feeding of the moth larvae. |
Several larvae of the stem-boring moth are exposed and visible
when the affected stems are opened. The feeding damage can cause
noni stems to die back. |
Necrotic and blackened young noni fruit and re-sprouting stem,
associated with feeding activity of moth larvae. |
Severe scarring and black pitting of Morinda citrifolia
may result from the feeding activity of the larvae of an unidentified
stem-boring moth. |
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| 4. LEAF MINERS |
Leaf miners leave a whitened trail or tunnel of destroyed noni
leaf tissue. |
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