Scientific name: Chilo partellus (Swinhoe)
Common name: Spotted Stalk Borer; Pink Borer
Synonyms: Chilo zonellus (Swinhoe)
Ethiopian name: Ageda Korkur
Order: Lepidoptera
Family: Pyralidae
HOSTS:
Main hosts: Maize, Sorghum, Bulrush millet, Sugarcane, Rice
Alternative hosts: Several wild grasses
IMPORTANCE IN ETHIOPIA:
Major pest of: Maize, Sorghum
Minor pest of: Wheat
DISTRIBUTION IN ETHIOPIA:
This species is most important at altitudes below 1500 meters above sea level.
In young plants the shoot can be killed, causing a “dead heart”. In older plants the upper part of the stem usually dies as a result of the boring of the caterpillars.
INSECT BIOLOGY & RECOGNITION:
Egg: The eggs are laid on the underside of a leaf near the midrib in 3-5 rows, in groups of 50-100. They are flattened, ovoid, and about 0.8 mm long. Hatching takes place after 7-10 days.
Larva: The young caterpillars produce characteristic leaf windowing. Sometimes the early stages mine in the leaves, causing yellow streaks. After a few days they bore down inside the funnel. They also may move down outside the stem and then bore into it just above an internode. In older plants the caterpillars sometimes live in the developed heads. In general appearance the caterpillars look like Busseola fusca larvae (= Maize Stalk Borer). They are creamy pink with groups of dark spots along the back. The head capsule is brown. When mature they are about 25 mm long. The caterpillars can be distinguished from B. fusca and from Sesamia calamistis (= Pink Stalk Borer) by the hooks on its prolegs. In C. partellus these hooks are arranged in a complete circle. In B. fusca and S. calamistis they are arranged in a crescent. The larval period takes 28-35 days.
Pupa: Pupation takes place in a small chamber in the stem. The pupal period takes 7 10 days.
Adult: Adult moths have a wingspan of 20-30 mm. Males are smaller and darker than females. The forewings of males are pale brown. The forewings of the females are much paler and the hind wings are almost white.
CONTROL METHODS:
Cultural control:
Stems and damaged cobs should not be left in the field. They might contain diapausing larvae which will be a source of infestation for the next crop. Crop residues should therefore be burnt, deeply buried, or fed to cattle. If stalks are to be dried for use as building materials, fuel, or other purposes, it is recommended to thinly spread them horizontally in the open field for several weeks. This will reduce the survival of diapausing caterpillars.
Observe a closed season of at least two months. When there are few hosts to feed on, this will prevent the continuity of the pest population.
Plant the crop as soon as possible after the rains begin and try to plant the whole crop in the area at the same time.
Thick stemmed grass weeds should be destroyed because they might serve as alternative hosts.
During the first six weeks of growth, pull out all plants with “dead hearts” and destroy them.
Crop rotation is recommended.
The larvae of Chilo partellus bore quickly into the stem. Therefore it is important to plant early so that plants can pass their vulnerable stage before the pest becomes serious.