Journal of Environmental Biology

Seasonal dynamics of wheat aphid complex and predator

Coccinella septempunctata in relation to

abiotic and biotic factors

Rajesh Soni¹, G.S. Deol¹?and Satnam Singh²*

¹Punjab Agricultural University, Ludhiana-141 004, India

²Punjab Agricultural University, Regional Station, Faridkot-151 203, India

*Corresponding Author email : drsatnamsinghs@gmail.com

 Publication Data

?Paper received:

?07 September 2011

?Revised received:

?07 June 2012

?Re-revised received:

?30 June 2012

?Accepted:

?08 August 2012

Abstract

Seasonal dynamics studies on wheat aphid complex, comprising of four major species and its predator Coccinella septempunctata were conducted in context to abiotic and biotic factors. The alate form of aphids appeared on the crop during the I^st?week of December. The colony build up of aphid complex started during the 2^nd?week of January and peak was observed after the I^st?week of March. Wheat aphid complex started declining in the last week of March and disappeared by mid April. The abiotic factors like maximum temperature and evaporation were most important for the buildup of aphids. The grubs and adults of C. septempunctata appeared on the crop during mid February and their population increased with the increase in aphid population. The grubs and adult population showed a strong positive correlation with aphid complex. The population of predators had significant positive correlation with maximum, minimum, mean temperature, sunshine and vapour pressure. The population of aphids declined after the 2^nd?week of March due to the rise in temperature, crop maturity and this in turn resulted in the lowering of the predator population. The studies evaluate in detail the abiotic and biotic factors regulating the wheat aphid complex and C. septempunctata populations under wheat agro-ecosystem.

?

Key words

Coccinella septempunctata, Wheat aphid, Biotic and abiotic factors

Copyright ? 2013 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).