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Studies were conducted to investigate the performance of eight Bt and five non-Bt cotton genotypes against whitefly and thrips and impact of abiotic factors on the population fluctuation of these sucking pests, at Cotton Research Station, Multan, during 2010 and 2011. The results exhibited that Bt genotypes found more susceptible host for the whitefly and thirps than non-Bt genotypes, during the course of years of study. Among Bt genotypes, maximum and minimum temperature showed significant and positive effect on whitefly population whereas relative humidity exerted negative effect during 2010. During 2011, the effect of all the factors was non significant. On cumulative basis, there was positive correlation between population of whitefly and minimum temperature. But in case of non-Bt, it has negative with maximum temperature whereas relative humidity had a positive effect on whitefly population. Similar trend was observed for thrips population on Bt varieties during both years but on non-Bt varieties only minimum temperature exerted strong positive impact on thrips population. Hierarchical regression models for whitefly and thrips revealed that minimum temperature was the most important factor (Bt and non-Bt varieties). Maximum temperature was the major contributing factor for whitefly fluctuation on Bt varieties during 2010. [ABSTRACT FROM AUTHOR]

Studies were conducted to evaluate the life history parameters and predatory potential of a stigmaeid mite Agistemus buntex Chaudhri against Tetranychus urticae Dufour at three constant temperatures viz., 20, 25 and 30°C. At 25°C, egg, larvae, protonymph, deutonymph and egg to adult stages were completed in 7.36, 3.00 2.44, 2.34 and 15.14 days, respectively for male, and 8.48, 3.98, 3.69, 3.52 and 19.67 days, respectively for the female. The development time was longer at other two temperatures. Daily fecundity, total fecundity and sex ratio was much greater at 25°C compared to 20 and 30°C. The lower development threshold was found to be 6.65 and 8.35°C for A. buntex female and male, respectively. Degree day requirements (DD) for A. buntex were 346.02 DD for female and 250 DD for the male. The intrinsic rate of natural increase (rm) of A. buntex was recorded as 0.11 at 25°C. Finite rate of increase (λ) values for A. buntex were found to be 1.07, 1.12 and 1.11 at 20, 25 and 30°C respectively. From obtained results, it can be concluded that A. buntex can become a strong candidate for biological control of T. urticae in Pakistan and elsewhere along-with other control strategies. The findings will serve as baseline information to better understand the biology of the pest, which can be utilized in an effective management program. [ABSTRACT FROM AUTHOR]

Mango (Mangifera indica L.) leaves are susceptible to severe attack by insect gall formers. The study's objective was to assess how different vertical strata of the tree canopy and variation in leaf traits affect gall formation. For this, individual and temporal variation in leaf traits of different mango cultivars (Anwar ratole, Chaunsa, Dusehri, Fajri, Sindri and Siroli) and their ultimate effect on gall formation were studied in 2009-10. In addition, the approximate quantity of carbon, nitrogen, phosphorus, potassium and water content in the leaves was also analysed. Significant variation was found among all mango cultivars for leaf traits and gall formation (p<0.05). Within host individuals, a maximum level of gall formation (200-240 galls, in case of Fajri cultivar) was found on the foliage of the upper tree canopy followed by the lower and inner canopy with the consistent pattern over 2 years. Moreover, gall formation showed significant correlation to carbon to nitrogen (C/N) ratio, phosphorus and potassium level in the leaves of all the studied cultivars except Siroli. [ABSTRACT FROM AUTHOR]