author(s)
Reda M Tabikha

abstract
Corn leaf aphidrnRhopalosiphum maidis and bird cherry-oat aphid R. padi, attackingrnmany host plants, which be recorded not only in most localities of Egyptrnbut also along a year. So, numbers of generations could be calculated andrnpredicted in all localities by employing Geographical Information System (GIS)rnand by exploiting calculated values of daily degree units and thresholds ofrndevelopment for them, with current and future thermal climatic conditions.rnEstimated biannually generations differ from region to another, that numbers ofrnwintery and summery generations of R. maidis ranged between 1 - 29 andrn12-50 generations, respectively under current conditions. Expected numbers ofrnbiannually generations will changed with rates ranged between -4:14 and -24:16rngenerations, respectively in 2050, and with rates ranged -3:15 generation andrn-42:17 generation, respectively in 2070. On other hand, Numbers of wintery andrnsummery generations of R. padi ranged between 1 – 27 and 11 – 42rngenerations, respectively under current conditions. Finally expected numbers ofrnwintery and summery generation in 2070 will be nearly similar to 2050, that itsrnchanging rates ranged between -3:14 generation and -36 : 16 generation,rnrespectively. Temporal spatial distributions and variations of generationrnnumbers in different regions and governorates of Egypt were discussed underrncurrent and future conditions. Moreover future of growing cereal crops was alsorndiscussed especially in southern reclaimed regions.