Opisina arenosella
| Opisina arenosella Walker | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Crytophasidae |
| Genus: | Opisina |
| Species: | O. arenosella |
| Binomial name | |
|
Opisina arenosella (Linnaeus, 1758) |
|
Opisina arenosella Walker, or the coconut black-headed caterpillar is common in multiple East Asian countries including Bangladesh, India, Sri Lanka, Mayanmar, as well as Indonesia. It is considered a pest to these countries, as they infest coconut palm trees, causing considerable damage to the trees, and reducing the plant's yield significantly. This is a great burden to all countries who experience infestations, as coconut is one of the main crops driving the economy. The species exists on coconut palms in all forms, from larval to moth, and utilizes the tree fronds as a main source of nutrition. Various methods of control have been explored, yet the primary control method is the administration of pesticides directly to the root of the coconut palms.
The coconut black-headed caterpillar is identifiable in the larval form as a caterpillar with greenish brown with dark brown head and prothorax, and a reddish mesothorax. There are often brown stripes on the body of the larva.
Post pupation, the caterpillar morphs into a moth which is greyish white in colour. The female is distinguishable from the male in that it has longer antenna, and three faint spots on the forewings, while the males have fringed hairs in the apical and anal margins of the hind wings.
The coconut black-headed caterpillar lays eggs in small groups on the under surface of coconut leaflets near to feeding larvae. Eggs hatch in three days on average, and then move into the larval stage where the larvae undergo a series of instars. Larvae of O. arenosella generally go through five instars, but have been recorded to go through as many as eight instars in laboratory settings. Instars from one to five last 6 days, 7 days, 7 days, 5 days, and 10 days respectively, which makes the larval stage approximately 48 days in length. Larvae are generally less than 4.0 mm in size between instars 1 & 3, between 4.0-11.0 mm from instars 4-6, and larger than 11.0 mm from instars 7 & 8. Some early larval and egg mortality has been observed in O. arenosella as a result of cannibalism on the eggs and younger larvae by older larvae. Adult coconut black-headed caterpillars rest under the surface of the damaged coconut palm leaves, where most of the damage to the coconut fronds can be observed. Larvae construct galleries of silk and frass, into which they retreat if disturbed. These galleries are also where pupation, which lasts approximately eight days occurs. Little is known about the moth form of O. arenosella. The organism is nocturnal, but their dispersal patterns are poorly understood.
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Wikipedia