7. Aphid: Myzus nicotianae , Myzus persicae  (Aphididae: Hemiptera)

Distribution and Status: Cosmopolitan, major pest

Damage symptoms

By constantly sucking the sap from leaves they make the plant pale and sick and thereby retard the growth. Sooty mould develops rendering the leaves unfit for curing. In addition they also transmit virus diseases like rosette or bushy top.

Bionomics:

Aphids are pinkish to brown or green small louse-like insects. Both apterous (wingless) and alate (winged) forms pass through 4-5 nymphal instars in their development and the nymphal period ranges from 5-7 days. Both the forms mate within a day or two after the final moult and start reproducing young ones. The apterous forms produce significantly more number of young ones than alate but their life-period is shorter than that of alate. In the field generally viviparous apterous forms are observed in large number. The winged forms are black or reddish with transparent wings. They are responsible for spreading the infestation from plant to plant and establish new colonies. Incidence of aphids reaches its peak from December and to first week of January.

Management

Spray acephate 75 SP 500 g or imidacloprid 200 SL 125 ml or thiamethoxam 25 WG  100 g in 500-800 L of water per ha. Leave one week gap between last spray and harvesting of leaf. Spraying should be done preferably in the evening hours.  After first spray, carry out subsequent sprays at 10- 15 days interval on the top 4-5 leaves of the infested plants only. It is necessary to leave a gap of two weeks between last spray and priming, otherwise the leaves will carry excess of insecticidal residues to the cured leaves.