Role of Coccinella septempunctata (L.) in management of cereal aphid, Sitobion avenae (Fab.) in subtropical wheat crop ecosystem

Rana, J. S. (2005) Role of Coccinella septempunctata (L.) in management of cereal aphid, Sitobion avenae (Fab.) in subtropical wheat crop ecosystem. Cereal Research Communications, 33 (2-3). pp. 577-582. ISSN 0133-3720

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Abstract

The alates of Sitobion avenae started settling on wheat during first week of January (standard week 1) simultaneously with the activity of its predator, Coccinella septempunctata . However, the population density of this predator at this stage was very less. From standard week 5, the aphid population started increasing steadily and colonies of alates and apterous aphids were seen on leaves and stem. Middle of February to the start of March was the most favourable period for multiplication of this pest. The maximum population of cereal aphid was observed during standard week 10 (second week of March), when wheat ( Triticum aestivum ) crop was in earing stage and the temperature was between 8.5 and 23.1° C along with a relative humidity of 45.7 to 88.3 per cent. The aphid started declining gradually during following weeks, finally disappearing by second week of April (standard week 15). Its predator, C. septempunctata was observed feeding on aphid colonies during standard week 4, which increased steadily till middle of April, when the aphid population started declining. This asynchrony in their population pattern in wheat crop is being contemplated to be the major cause of flare up of the population of this pest. The correlation drawn between different stages of predator and aphid population revealed that the collective contribution of these factors was 93.92 per cent. Abiotic (temperature and relative humidity) and biotic (predator) factors were observed to be significantly influencing the aphid population in this crop ecosystem.

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