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Abbas Q.,Entomological Research Institute | Ahmad I.,Pest Warning and Quality Control of Pesticide | Shahid M.A.,Pest Warning and Quality Control of Pesticide | Akhtar M.F.,Entomological Research Institute | And 3 more authors.
Pakistan Journal of Nutrition | Year: 2014

A field study was carried out to determine the role of weather factors on canola aphids population. Aim of this study was to investigate, how meteorological factors play a role in fluctuating aphid population. The experiment was conducted on canola crop grown under three farming systems i.e., synthetic fertilizer, farm yard manure and untreated control. Aphid population was recorded from 1st week of February to 2nd week of March during 2009 and 2010 and weather data was collected from metrological observatory during the same period. The results revealed that a peak aphid population was recorded during the beginning of 2nd week of March in both years of the study. Aphid density was positively associated with maximum as well as minimum temperature while it showed a negative correlation with relative humidity. The rainfall during 2009 showed significant and negative correlation with aphid population while during 2nd year of studies (2010) it showed non significant correlation. On division of aphid infestation period into different phases of infestation, it was observed that during the establishment phase, the rainfall and relative humidity were negatively correlated, whereas, temperature was positively correlated while, during the declining phase temperature had negative relationship with aphid population build up. © Asian Network for Scientific Information, 2014.

Saleem M.,Entomological Research Institute | Hussain D.,Entomological Research Institute | Ghouse G.,Pest Warning and Quality Control of Pesticide | Abbas M.,Entomological Research Institute | Fisher S.W.,Ohio State University
Crop Protection | Year: 2015

Studies were carried out to evaluate the resistance of Pakistani populations of the beet armyworm, Spodoptera litura (F) to several commonly used insecticides. Different field populations of S. litura from four districts of the Punjab were monitored from 2009 to 2011 for resistance to insecticides using a standard leaf dip bioassay method. For organophosphates and pyrethroids, resistance ratios compared with a susceptible Lab-Pk population were in the range of 8-109 fold for deltamethrin, 11-139 fold for cypermethrin, 19-143 fold for chlorpyrifos and 39-162 fold for profenofos. For new chemistry insecticides, resistance levels were 2-74 fold for spinosad, 4-216 fold for abamectin, 7-87 fold for indoxacarb, 2-77 fold for emamectin benzoate, 1.9-58 fold for lufenuron and 4-43 fold for methoxyfenozide. Pairwise correlation coefficients of LC50 values showed a positive correlation with cross-resistance among deltamethrin, cypermethrin and chlorpyrifos, while resistance to profenofos showed correlations with resistances to other insecticides except chlorpyrifos. New chemistry insecticides showed no correlations between any of the tested insecticides. There were high to very high levels of resistance to organophosphates in most of the population, which suggested that the use of these should be avoided against this pest. Selective use of pyrethroids in several areas, including Bahawalpur and Lodhran, where the pest showed a low level of resistance, would appear to be acceptable, the new chemistry insecticides, lufenuron, methoxyfenozide, emamectin and indoxacarb had no, very low, low and moderate resistance levels against populations, respectively. These are considered to be safe to the environment and safer to natural enemies. © 2015 Elsevier Ltd.

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