Population Dynamics of Thrips tabaci (Lindeman) in Relation to Abiotic Climate Factors on Bt and Non-Bt Cotton Cultivars Muhammad Hannan Ahmed 1 , Muhammad Irfan Ullah 1, *, Abu Bakar M. Raza 1 , M. Afzal 1 , A. Khaliq 1 , Yasir Iftikhar 2 and Haiz Muhammad Aatif 3 1 Department of Entomology, University of Sargodha, Sargodha, Pakistan 2 Department of Plant Pathology, University of Sargodha, Sargodha, Pakistan 3 Department of Plant Pathology, Bahaudin Zakariya University, Bahadur Subcampus Layyah Article Information Received 25 March 2015 Revised 13 April 2017 Accepted 25 May 2017 Available online 12 October 2017 Authors’ Contribution MHA planned and conducted study. MIU reviewed and interpreted results. ABMR helped in data collection and analysis. MA critically reviewed and interpreted results. YAand AK helped in data analysis. HMA reviewed and helped in planning and conducting the study. Key words Bt cotton, Thrips tabaci, Population dynamics, Abiotic factors, Environment. Cotton is an important ibrous crop and called as white gold of Pakistan. Like many other crops, various chewing and sucking insect pests attack on different Bt and non-Bt cotton genotypes. Furthermore, metrological factors (especially temperature, relative humidity and rainfall) also play vital role in the population dynamics of sucking insect pest complex like jassid, aphid, thrips and mites. The present study was conducted on six cotton cultivars (3 Bt and 3 non-Bt) to monitor the population dynamics of thrips in relation to abiotic climatic factors. Interaction effect was found signiicant in Bt varieties but not for non-Bt cultivars. Average thrips population per leaf on various Bt and non-Bt varieties showed that the CIM-557 along with BT-703 had the highest number of thrips density while Bt variety FH-113 had the lowest thrips population per leaf. Similarly, in relation to thermal effect, high thrips population was recorded at 29-35 o C but population declined at 40°Ċ. Findings are helpful for appropriate management of sucking complex in case of cotton crop. INTRODUCTION T he Gossypium is the genus of the cotton having hard seed coat. Cotton growing history is as old as human beings. Tropical and subtropical regions of the world including United States of America (USA), China, India and Pakistan are the most leading cotton producing countries of the world (Allen, 2000; McKinion et al., 1989; Saeed et al., 2007). It is the main ibrous crop which provides different products for domestic usage (Ali et al., 1993). Cotton, rice, wheat and sugarcane are the major agronomic crops of Pakistan which accounts about 33.4 percent (Shaiq and Rehman, 2000). The average cotton yield of cotton in Pakistan is 571 kg/ha which is very less as compared with the other cotton growing countries as it is attacked by several insect pests. Losses in cotton crop have reported by attack of about 162 species of different insect pests and plenty of diseases (Manjunath, 2004). In cotton growing areas, cotton provides 40% cash income for rural household products. Moreover, exporting cotton, our earning comprises as * Corresponding author: mirfanullah@uos.edu.pk 0030-9923/2017/0006-1937 $ 9.00/0 Copyright 2017 Zoological Society of Pakistan much as 60 percent. Unreined material provided to 1200 ginning factories, 458 textile mills and 5000 oil expellers (Nazli and Meilke, 2008; Agha, 1994). Besides the agronomic practices used in cotton production that increase the chances of pest outbreaks, environmental conditions are also important in the population dynamics of different insect pests (Khaliq et al., 2014; Hasan et al., 2013). Other than chewing insect pests, sucking insect pests are playing an important role in the damaging to the crop. They suck cell sap from their piercing sucking mouthparts from the twigs, shoot, stem and leaves. Discoloration of leaves occurs due to the sucking of these pests (Khaliq et al., 2014). Thrips and mites favor low rainfall and high relative humidity for their proper development (Khaliq et al., 2014). During favorable conditions, these pests cause heavy losses to development and growth of the crops (Zhang et al., 2013). Thrips (Thysoptera: Thripidae) are very small insects having orange yellowish to brown color (Mass, 2013) with deinite type of strippy wings (Lewis, 1997). Thrips are cylindrical, and adult have yellow to brown color. Pupation of the thrips occurs in the soil among fallen fruits or in crakes and crevices. Thrips mostly become active throughout the year and heavy populations pose sever losses (Mound, 2005). Moreover, ABSTRACT Pakistan J. Zool., vol. 49(6), pp 1937-1943, 2017. DOI: http://dx.doi.org/10.17582/journal.pjz/2017.49.6.1937.1943