الفهرس 
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Abstract
This study investigates the season fluctuations of Spodoptera littoralis (Boisd.) moths and predicting of generations in cotton fields in relation to accumulated heat units by using sex Pheromone traps at the experimental farm, Sakha Research Station, Kefr El-Sheikh region, Egypt during 2016 and 2017 cotton growing seasons. Results indicates that S. littoralis moths had six peaks occurred from the 3rd week of May until the 1st week of September the highest number of moths was recorded during the end of June which being 8023.2 and 20 63.2 moth/ trap/ 30 days and 60 days after cotton planting in both seasons, respectively. The predicted peaks of generations could be detected when the accumulated thermal units recorded 525.42 DD’s. On the other hand, the highest mortality percentages of the 4th larval instar of S. littoralis were recorded five days after treatments, 98,49,96.49 and 91.81% for Chlorpyrifos, Lufenuron and Indoxacarb under semi-field conditions respectively In addition, Silica nanoparticles (SiNPs) gave the highest efficiency against the 4th larval instar of S. littoralis with LC50 values of 258.8843 ppm followed by Gibberellic acetic acid (287.4862 ppm) and Ethephon (320.4196 ppm), recorded three days after treatment. Gibberellic acetic acid was the most effective treatment with LC5o values of 207.6850 ppm against Bemisia tabaci (Genn.) (immature stage) followed by Ethephon (285.3632 ppm) and SiNPs (347.0463 ppm), recorded three days after treatment Gibberellic acetic acid was the most effective treatment until five days after treatment against Aphis gossypii Glover with LC50 values of 224.2301 ppm while SNiPs was 250.4571 ppm followed by Ethephon was 295.872 ppm. Gibberellic acetic acid was the most efficiency until five days after treatment against Empoasca spp. with LC50 values of 177, 2563 ppm followed by SiNPs (189.6238 ppm) and Ethephon (358.558 ppm), respectively. Population fluctuations of A. gossypii, B. tabaci and Empoasca spp. showed two peaks during August, September and October in both studied seasons. Ethephon (plant growth regulator) treatment gave the highest reduction percentage, 56.68 and 37.60% of pink bollworm infestation pectinophora gossypiella (Saund.) with 3 cm3 /L, while they were 50.66 and 43.75 % of spiny bollworm infestation, Earias insulana (Boisd.) with 1.5 cm3/ L during 2016 and 2017 late cotton seasons. Concentration of Ethephon; 2.5 cm3/L gave the highest significantly increasing of percentages of mature boll opening recording 36.68 and 22.57% in the two tested seasons, respectively. Key words: Spodoptera littoralis (Boisd.), peaks, predicting, generations, thermal units accumulations, Chlorpyrifos, Lufenuron, Indoxacarb, Sílica nanoparticles (SINPs), Gibberellic acetic acid, Ethephon, Bemisia tabaci (Genn.), Aphis gossypii Glover, Empoasca spp., pink bollworm, Pectinophora gossypiella (Saund.), spiny bollworm, Earias insulana (Boisd.).