EFFECT OF NITROGEN FERTILIZATION DOSES OF COTTON CROP INSECTS AND THEIR CERTAIN ASSOCIATED PREDATORS

Abstract

Field experiments were carried out at Sidi Salem District, Kafr El-Sheikh governorate to study the influence of two nitrogen rates in combination with phosphorus (P) and Potassium (K) at their balance rate N:P:K = by ratio of (67:30:24) and high (N) rate 1.5N:P:K by ratio of (100.5:30:24) on the population numbers of cotton aphids and whitefly(adults) infesting cotton crop in addition to some associated predators during tow seasons (2011 and 2012). Obtained results revealed that the population densities of aphids and whitefly(adult) were maximum during mid and later stages of cotton seasons according to temperature (Temp.) and relative humidity (R.H %) levels. The highest means of aphid, whitefly and associated predators populations in both study seasons were scouted in plot fertilized with high N fertilization 1.5N:P:K and vice versa. Statistical analysis showed highly significant differences between the population means of aphids, whitefly(adults) and associated predators No. in the two fertilizer ratios in both seasons. Also, the population densities of aphids and whitefly was higher in 2012 than that in 2011 season, it is dependent upon of the corresponding Temp. and R.H %. On the other hand, insignificant positive correlation was found between predators and aphids and whitefly (0.290 and 0.042) respect. in plants fertilized with N:P:K ratio, while there was highly positive correlation (0.697 and 0.608) with both sucking insects respect. in 1.5N:P:K during 2011 season. But, in 2012, season predators was positive and highly significant correlated (0.789 and 0.881) with aphids and whitefly respect. in fertilization ratio 1.5N:P:K. Highly significantly positive (0.728 ) and significant positive (0.500) correlations were found with aphids and whitefly respect. with fertilization N:P:K ratio.