Population Dynamics of the Whitefly, Bemisia Tabaci (Gennadius) (Homoptera: Aleyrodidae) on Common Bean, Phaseolus Vulgaris in Relation to Cultivar, Temperature and Humidity
Amal I. Safe , EL-Saied A. Naiem, Horia. A. Abdel-Whab and Kamal M. El-Gendy
The objectives of this study were to find the correlation between population dynamics of the whitefly, Bemisia tabaci, Phaseolus vulgaris cultivars, temperature and humidity during the summer and winter growing seasons of 2013 and 2014. The three P. vulgaris cultivars screened were Copy, Polesta and Manga. In 2013 and 2014 cropping seasons, the population densities of B. tabaci gradually increased from the 3rd week of March until the 4th week of April. For, the population density increased and reached a peak from the 1st week of May, and then the population density decreased gradually from the 4th week of May until the 3rd week of June in 2013 and 1st of June in 2014. Densities of this pest typically increased as the growing season progressed and reached a peak in November and started to decrease from 1st of December until the end of them. In 2013 and 2014 cropping seasons, the population densities gradually increased from the 2nd week of October until the 4th week of October. Furthermore, the population density reached a peak from the 1st week of November, and then decreased gradually from the 4th week of November until the 4th week of December in 2013 and 2014. In 2013 summer cropping season, the cultivars Copy and Polesta were the most infested varieties. A similar trend was observed during 2014 summer growing season. In 2013 winter cropping season, the cultivars Copy and Manga were more susceptible to white fly infestation than Polesta cultivar. A similar picture was obtained during the winter cropping season of 2014. The most infested varieties were Copy and Manga respectively. Whereas Polesta variety was the least infested. B. tabaci population density was positively affected by temperature in 2013 and 2014 summer growing seasons, where the correlation coefficient were 0.64 and 0.6, respectively. In contrast, in 2013 and 2014 winter cropping season the relationship between B. tabaci population and temperature was insignificant and/or significant and negative with a correlation coefficient of -0.14 and -0.61 respectively. The results revealed that the relative humidity showed non-significant positive association with B, tabaci abundance in 2013 summer growing season with correlation coefficient of 0.08. On the other hand, B. tabaci density showed non-significant negative association with relative humidity in 2014summer season and 2013 winter seasons and significant negative association in 2014 winter season with correlation coefficients of 0.18, 0.73 and 0.32 respectively.
Keywords: Bemisia tabaci; Population Dynamics; Whether Conditions; Common Bean.