ECOLOGICAL STUDIES ON CERTAIN PIERCING SUCKING PESTS INFESTING SUGAR BEET CROP AND THEIR ASSOCIATED NATURAL ENEMIES IN SHARKIA GOVERNORATE, EGYPT.

         The present work was carried out at Diarb- Nigm district, Sharkia Governorate, during the two successive growing sugar beet seasons 2010/2011 and  2011/2012, to study the population fluctuation of certain sucking pests and their associated natural enemies. The obtained results  showed that the population fluctuation of common aphid Myzus perseica (Sulzer) and Aphis craccivora Koch, leafhopper Empoasca decipiens (Paoli) , Empoasca decedens (Paoli), Nezara verdulla Lins and two-spotted spider mite Tetranychus cucurbitacearum  (Sayeg)and their associated natural enemies of predator mite Amblyseius swirskii as well as the effect of temperature  and relative humidity. The aforementioned insect pest species were collected by two different methods from sugar beet plants using direct counting (plant sample) and sweep net. The obtained results showed that the plant sample proved to be the best method to collect aphid, green bug insect species and two-spotted spider mite of the present work, while  the sweep net proved to be the best technique to collect the leafhopper insect species. The seasonal abundance of  M. persicae on sugar beet plants recorded two peaks for M. persicae. The first one was occurred at 2^nd week of December, the second peak was found at 4^th week of January. The leafhopper E.  decipiens and E. decedens were recorded two peaks, the first  peak was recorded at 2^nd week of Novamber, while the second peak was occurred at 1^st week of February for E. decipiens and E. decedens for the two seasons, respectively. Two peaks were recorded for N. verdulla the first one was occurred at 2^nd week of December, while the second peak was recorded at 1^st week of February.  The mite (adult and immature stages) recorded two peaks, the first peak of adults and immature stages at 2^nd week of October 2010/2011 and 4^th week of October 2011/2012, respectively. The first peak of eggs at 2^nd week of October 2010/2011 and 1^st week of November 2011/2012, respectively. The second peak was recorded for mite (adult, immature stages and eggs), the second peak of adults at 3^rd week of  March 2010/2011  and 4^th week of  March 2011/2012,of immature stages at 2^nd week of  November 2010/2011  and 3^rd week of  March 2011/2012 and of eggs at 4^th week of  October 2010/2011  and 3rd week of  March 2011/2012, respectively. Two peaks were recorded for predator mite A. swirskii. The first peak at 4^th week of February 2010/2011and 2011/2012, respectively. The second peak was recorded at 4^th week of March 2010/2011and 2011/2012, respectively. This research aims to utilize the obtained results in developing the IPM programs against these pests on sugar beet plants through activation the effect of both temperature and relative humidity on insect numbers.