Academic Research Journal of
Agricultural Science and Research
Academic Research Journal of Agricultural Science and Research
Vol. 3(8), pp. 207-218. August, 2015.
Full Length Research
Estimate the effect of climatic factors on population density of parlatoria date scale insect, Parlatoria blanchardii by different models of correlation and regression
Bakry, M.M.S.1, Roya Arbabtafti 2, M.A.A. Abdrabbo3 and S.F.M. Moussa1
1 Scale insects and Mealybugs Research Dept., Plant Protection Research Institute, A.R.C, Dokii, Giza, Egypt.
2 Department of Agricultural Entomology Research, Iranian Research Institute of Plant Protection, Tehran, Iran.
3 Central laboratory for Agricultural Climate (CLAC), Agricultural Research Centre, Giza- Egypt
Accepted 4 July 2015
The parlatoria date scale insect, Parlatoria blanchardii (Targioni-Tozzetti) (Hemiptera: Diaspididae) is a serious pest on date palm trees in Egypt. The adults and nymphs of this insect sucking great amount of plant sap that give low rates of photosynthesis and respiration which leads to curling, yellowing, dryness and leaves shedding. The present work was carried out to study the impact of climatic factors on population density of P. blanchardii infesting date palm trees by different models of correlation and regression during the current year (average five years from 2009 to 2013) at Esna district, Luxor Governorate, Egypt. The results revealed that the monthly observations of the total population of P. blanchardii had three to four peaks of seasonal activity per year. The results showed simple significant positive correlation between the mean temperature and different stages of P. blanchardii and total population of insect. Similarly, the relation between mean dew point and different stages of P. blanchardii and total population of insect was significantly positive. Differently, the simple correlation between mean of relative humidity and different stages and total population of insects was significantly negative. Among five models of regression, the quartic degree of polynomial regression was exhibiting the highest percentage of explaining variance (E.V.%) as compared with the other models in all studied relations. Also, linear and logarithmic regressions were significant in all studied relations. The results revealed that the mean dew point was below the optimum range for activities of nymphs, adult females and total population of P. blanchardii. The most effective variable in population changes was mean dew point and it was 28.05, 23.42 and 26.41% for nymphs, adult females and total population of insect, respectively. The results demonstrated that the combined effect of maximum temperature, relative humidity and dew point was significant effect on the numbers of nymphs of P. blanchardii. The percentages of explaining variance (E.V.%) indicated that the effect of all tested climatic factors on population changes of nymphs, adult females and total population of insect were responsible for 73.9, 65.5 and 71.2%, respectively.
Key words: Parlatoria date scale, Parlatoria blanchardii, seasonal activity and climatic factors.
How to cite this article: Bakry MMS, Arbabtafti R, Abdrabbo MAA, Moussa SFM (2015). Estimate the effect of climatic factors on population density of parlatoria date scale insect, Parlatoria blanchardii by different models of correlation and regression. Acad. Res. J. Agri. Sci. Res. 3(8):207-218.