Abstract:
The present dissertation consisted of six chapters in addition to a general introduction and review of literatures. The introduction deals with the importance of aphids as pests, carriers of viruses, their numbers, host specificity and speciation, morphs and life cycles. Concepts and components of 1PM, it's brief history, constraints as well as foundation and pillars of IPM are also discussed in this section. Rationale, aims and objectives of the present investigation are also included at the end of general introduction. Related works to the present investigation both from home and abroad are mentioned under the title of"Review of Literatures". Chapter 1 contains the population dynamics of three aphid pests viz., Aphis craccivora Koch, Aphis gossypii Glover, Lipaphis erysimi (Kalt.) (Homoptera: Aphididae) infesting bean, brinjal and mustard plant respectively. Population of natural enemies of said aphids were also recorded. Highest population of A. craccivora was recorded (71.66±1.67 per twig) in the 3rd week of December, 2003 and lowest (9.00±0.58 per twig) in the l st week of November, 2003. Population of A. gossypii was highest (17.00±1.16 per plant) in the 4th week of December ,2003 and lowest (2.00±0.58 per plant) in the 4th week of January, 2004 and the population of L. erysimi reached to its peak (43.00±1.53 per twig) in the 4th week of December, 2003 and lowest (9.66± 0.33 per twig) in the 2nd week of November, 2003. The impacts of environmental factors viz., temperature, relative humidity, dew point and rainfall on the weekly nwnber of aphids and their natural enemies were investigated by calculating the degree of relationships between the said variables. In order to do this analysis of 'r' (Correlation co-efficient) values were calculated separately.
Description:
This Thesis is Submitted to the Institute of Biological Sciences (IBSc), University of Rajshahi, Rajshahi, Bangladesh for The Degree of Doctor of Philosophy (PhD)
