PEST OF OILSEED (ACHAEAJANATA) UPSC LONG ANS

PEST OF OILSEED (ACHAEAJANATA)

Host: This is a pest of castor, pomegranate, rose, Zizyphus, Euphorbia, Tridax, Cardiospermum, Ficus, Bauhinia, Citrus, mango etc.

Damage: Larvae defoliate plants quickly by feeding gregariously and voraciously. Midribs and veins are left intact and other parts of the leaves eaten up. Being larger in size, their capacity to cause damage is enormous. Young plants cannot sustain damage and die. Adults are fruit-sucking moths that prefer to suck juice from mango and citrus and fruits.

Life cycle: Adult moths are grayish-brown in colour with wavy lines on the fore wings. Hind wings are black in colour and have one large median and three marginal white spots. They are medium sized robust moths.

Eggs are round, bluish green in color, ridged and are laid singly on tender shoots, usually on the undersurface of the leaves. Fecundity of a female is 450 eggs. Incubation period varies between 2-5 days after which a tiny larva hatches out which is slender and yellowish-green in colour.

Young larvae are usually gregarious but as they grown they get scattered on leaves. A full grown larva is a typical semilooper, has a bluish-black body with a black head and reddish spots on the back and a reddish anal tubercle. Legs are missing on the median segments which makes it walk with looping action. Sometimes there are faint reddish-brown or whitish stripes on the body.

Full grown larva measures about 7 cms. There are 5-6 instar and the whole larval period is about 15-20 days. Pupation takes place in soil or among fallen leaves. Pupal period is 10-15 days but may be prolonged to few months under winter conditions.

Distribution: The pest is distributed in the whole of Indian subcontinent. Thailand, Malaysia, Philippines and Indonesia.

Control: As the larvae are large and prominent on the leaves, destroying them by handpicking is quite easy. They are also eaten by birds in large numbers.

Chemical control can be achieved by spraying endrin 0.02%, parathion 0.025% or by spraying 0.02% of diazinon, toxaphen, carbaryl, endosulfan and methyl parathion.

Biological control involves conservation of the following parasitoids:

Egg parasites: Trichogramma evanescens. Larval parasite: Apanteles sundanus, A. ruidus, Microplitis maculipennis, M. ensirus, M. similes, Euplectus leucostomus, Paniscus ocellaris, Zamesochorus orientalis, Tetrastichus ophiusae, Rogas percurrens and Enicospilus sp.