1. Banana aphid

1.Banana aphid - Pentalonia nigronervosa Coq. (Aphididae: Hemiptera)
    Damage
    • There is no direct damage caused by this pest but it acts as a vector for the notorious virus disease bunchy top disease of banana.
    • The disease is characterised by the initial appearance of green streaks on the secondary veins on the ventral side of lamina.
    • The affected leaves become brittle and petioles completely elongated.
    • The leaves become small and eventually the crown of plants becomes composed of stunted leaves, which present bunchy top appearance.
    Bionomics
    • The adult viviparous insects are of two forms, winged and wingless.
    • The alate viviparous female has reddish to dark- brown body measuring on an average of 1.45 mm in length. In the apterous viviparous female the body is reddish to dark brown measuring on an average 1.55 mm in length.
    • The male insects are not observed. The female reproduces parthenogenetically.
    • The female gives birth to young ones from the second day, of its emergence.
    • A female brings forth 32-50 young ones. The nymph has 4 instars conferring a period of 8-9 days.
    • The aphids occur on banana plant in colonies.
    • They shelter at the base of the pseudostem, top region of the pseudostem and leaf axils.
    • The population is high from early September to late January with two peaks in between one during September-October and the other during December-January.
    • Moderate temperature and high humidity favours the increase in aphid population.
    • Infective aphid can transmit the virus to healthy plant in 1.5-2 hours of feeding.
    • The minimum acquisition feeding time for nymph is 16 hours.
    • The aphid remains infective for up to 13 days after feeding on infected material.
    Management
    • Spray methyl demeton 2 ml / litre or monocrotophos 1 ml / litre or dimethoate 1.70 ml / litre of water,
    • Direct the spray towards the crown and pseudostem base up to ground level at 21 days interval at least thrice.
    • Avoid injection of monocrotophos after flowering.
    • Destroy diseased plants with rhizome.
    • Inject 5 ml of 2, 4-D herbicide (125 mg/1) into pseudostem using injecting gun for effective killing of diseased plants.
    • Spray methyl demeton 25 EC 500 ml or monocrotophos 36 WSC 250 ml/ha or dimethoate 30 EC 500 ml/ha to control aphids. Direct spray towards crown and pseudostem base at 21 days interval at least thrice.
    • Follow pseudostem injection with monocrotophos 36 WSC after diluting 1 ml in 4 ml of water at 45 days interval. Use banana injector devised by TNAU or lumbar puncture needle. Avoid injecting monocrotophos after flowering.
    • Encourage activity of predators, Scymnus, Chilomenes sexmaculata, Chrysoperla carnea and other coccinellids; and entomopathogen, Beauveria bassiana.

Last modified: Monday, 6 February 2012, 11:22 PM