~ 2 ~  Journal of Entomology and Zoology Studies 2016; 4(1): 02-06 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2016; 4(1): 02-06 © 2016 JEZS Received: 01-11-2015 Accepted: 01-12-2015 Amjad Ali Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Haider Karar Entomological Research Sub- Station, Multan, Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Muhammad Farooq Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Faisal Hafeez Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Muneer Abbas Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Touseef Khan Babar Entomological Research Sub- Station, Multan, Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Correspondence Faisal Hafeez Entomological Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan. Influence of weather factors on the trapped population of pink bollworm ( Pectinophora gossypiella ) under Multan Agro-ecosystem Amjad Ali, Faisal Hafeez, Muhammad Farooq, Haider Karar, Muneer Abbas, Touseef Khan Babar Abstract Studies were carried out to evaluate the impact of weather factors on the population dynamics of pink bollworm for three consecutive years from 2009 to 2011 at Entomological Research Sub-station, Multan. Pheromone traps charged with Gossyplure [(Z, Z) and (Z, E) 7, 11 hexadecadienyl acetate] were installed and data for moth catches was recorded regularly at fortnightly basis. Simple correlation and regression coefficients were also computed to know the relationship between weather factors and moth catches. The results indicated that highest peaks of pink bollworm appeared during April having 1.1 and 1.13 moths/trap at 37.78 and 36.78 o C (maximum temperature), 22.00 and 20.12 o C (minimum temperature), 29.89 and 28.46 o C (average temperature) and 67% (RH) during 2009 and 2011 respectively whereas peak appeared in November and December during 2010. Out of weather factors, maximum temperature and rainfall showed positive response while minimum temperature, average temperature and relative humidity had a negative impact on the population fluctuation of pink bollworm. Regression coefficient showed 8.92% impact of weather factors in population fluctuation. Keywords: Pink bollworm, Multan, Climatic changes, Regression analysis 1. Introduction Cotton is one of the most sensitive crop to the pest attack and chemically intensive among all fields. In Pakistan, bollworms are considered as major pest of cotton. Apart from cotton they also cause serious damage to number of other crops particularly the summer vegetables such as okra, tomato, tori, chilies and different cucurbits etc. Ahmed [1] reported that cotton crop is the most susceptible to bollworm, which inflect heavy damage that may vary from year to year but generally cause 20-30% of yield reduction. Ghouri [8] reported about 20% loss of yield by different bollworm pest only. Pectinophora gossypiella is one of the major lepidopteron pests of this region and cause significant infestation throughout the world. It causes an enormous damage and loss of cotton yield when it neglected [7] . Hutchison et al. [12] reported that young larvae of P. gossypiella penetrate in to the young bolls and flowers two hours after the hatching. The pink bollworm larvae feed on flower buds, flowers, bolls and seeds, and the termination of growth results in boll rotting, premature or partial boll opening, reduction of staple length, strength, and increases trash content in the lint. Sex pheromones are being used to monitor emergences of over winter population of pink bollworm (a successful technique for monitoring and mating disruptions) [16, 18] . Hummel et al. [11] identified the sex pheromones for pink bollworm as 1:1 mixture of (Z, Z) and (Z, E) 7, 11 hexadecadienyl acetate, named gossyplure. Boguslawski [4] used sex pheromones and pesticides in different plots for control of P. gossypiella, and found sex pheromones more successful than pesticides. Being cold blooded organisms, the effect of temperature on insects largely overwhelms the influence of environmental aspects [3] . Temperature exerts great impact upon the total number of eggs and on the ovipositional behavior of insects [5] . More often rainfall may have a negative impact on the insect population because eggs and neonates of some insects may be dislocated or killed by rain [14] . Its population increases during rainy season and population drop with increase in temperature. Different stages of the insect prolonged developmental period during winter and coloration also changes with change in temperature and humidity [17] . Insects are capable of surviving only within certain environmental limits, so one can predict the occurrence of peak activities of a given pest