Study on Population Changes of Important Sucking – Pests (Aphis Gossypii (Glov.) and Bemisia Tabaci (G.) in the New Varieties Second Plant (After Canola) in the Golestan Province of Iran.

Investigating the population dynamic of important cotton pests on new cotton varieties is important. Cotton cultivars have important pests such as thrips, aphids, whitey and bollworm. Considering the premature cultivars with proper yield for second cultivation in cotton-growing Golestan province at the north of Iran, this study seems necessary. This genotypes was cultivated with 9 treatments in 4 replicates. A completely randomized block design was carried out in Hashem Abad research station in a spray-free plot with the dimensions of 30 × 80 cm in 2018-2019 years. According to the results of this study, analysis of variance of two years showed that the yield of N2G80 with 1538 g in the plot with 41.7% lint percentage had the highest yield, and M13 with 685 g in the plot and 35.8% lint percentage in the lowest yield they had.The infestation rate of the genotypes tested in the population of green aphid of cotton in K880-2 and Golestan® cultivars was 48.88 and 40.31 in aphid with the highest density, and the SKT-133 and TBL-60 genotype respectively with 27.15 and 29.11 aphids per leaf had the least infestation. The amount of infestation of the genotypes tested to the population of whitey cotton on the N2G80 and TBL-60 genotype was 90.76 and 68.86 whitey in the leaf with the highest infestation and N2G80 and TBL-60 genotype respectively with 40.05 and 75.51 white y in leaf were the least infested. Correlation coecient between traits was equal to 0.55. The number of bolls per plant was not correlated with other traits including boll weight, lint percentage, aphid and white y.

amount of infestation of the genotypes tested to the population of white y cotton on the N2G80 and TBL-60 genotype was 90.76 and 68.86 white y in the leaf with the highest infestation and N2G80 and TBL-60 genotype respectively with 40.05 and 75.51 white y in leaf were the least infested. Correlation coe cient between traits was equal to 0.55. The number of bolls per plant was not correlated with other traits including boll weight, lint percentage, aphid and white y.

Introduction:
More than 200,000 hectares of land annually are allocated to cotton cultivation in Iran. Cotton cultivars have important pests such as thrips, aphids, white y and bollworm. Changes in the population of major cotton pests in Golestan province were shown on new cultivars in cotton regions of the country relative to normal cropping in the region that cultivars tolerant to the most important pests of sepid cotton had the lowest infection with bell worm and sucker pests (aphids and white y) in the Golestan province region. (Darvish,Mojeni,1994,1996and 1996. A study was conducted on the cultivars tolerant to cotton aphid in Hashemabad station. Akala.S.J × ciland-2 variety has the lowest infection with cotton aphid and other cultivars, such as Zeta − 2, 010, Bakhtegan and Bulghar 433, had moderate infestation (Darvish, Mojeni, 2000). Pest activity of cotton in the region with two important peaks in early June in early June and early July in Gorgan and Gonbad (Darvish, Mojeni ,2006).
White y is one of the most important pests of Golestan province that started its activity in late July due to its favorable weather conditions and is observed at the end of crop season with considerable density.
The infestation rate of different cotton varieties in cotton honey showed that the cultivar sepid has the lowest infestation with cotton white y due to low leaf area and low cracking compared to other cultivars. Among other cultivars, 17 varieties showed a low resistance, six cultivars were susceptible and the remaining two cultivars showed high susceptibility to aphid damage (Susa, et al.,1997). Several cotton cultivars and lines in Pakistani province were examined for morphological characteristics related to pest resistance and it came to the conclusion that the earliness in the cultivars makes it possible to ee from the end of the season's white y and bollworm (Kumar and Saini, 2008). An investigation has been conducted on the economic threshold of aphid control and tolerance of the cotton plant to the aphid (Gao, 1989). In India, the cotton white y population dynamic with the use of sticky yellow traps for pest prevention (Nandihalli, et al., 1993 ). In India, studies on eleven varieties of Gossypium arboreum, G. hirsutum, G. haerbaceum cotton species have been performed to determine the aphid tolerant variety and state that according to the morphological and anatomical analysis of cotton plants, the varieties that are cortical and also the leaves with thick parenchyma and the distance between the barrows at the lower level of the leaf is important for feeding the pest. Therefore, the aphid activity on the varieties with these characteristics is more than the varieties that have no sting or dense sting at the plant's puberty at the leaf surface (Khan and Agarwal, 1990 ). Studying on the preference of cotton-green aphids on six cotton cultivars in Greece in 2006. The results showed that Eva cultivar had a high trichome density on leaf with a population of 58-62 aphids in leaf and the Zeta-2 cultivar had the lowest aphid population with the lowest trichome density on the leaf of aphid, 29-33 aphids in leaf of the least aphid population (Kosas,et al., 2006).
The genotypes RS2098, CNH911, and PA183 were non-preferred for oviposition and exhibited an antixenosis mechanism of resistance in cotton to white y. The genotypes NHH44, LK861, Supriya, RS2013 and LD694 were categorized as moderately resistant in cotton to white y.

Results:
Based on studies carried out over a two-year trial and by statistical analysis, data conversion and composite variance analysis was performed using Mstatc software. In terms of the average cotton yield, the highest yield (1538 gr / plot) and M13 (35.8% lint percentage in the lowest yield) (685 gr / plot) in the two years of N2G80 cultivars with 41.7% lint percentage) other genotypes included SKT133 (32.6%), GT40 (32.9%), TBL60 (35.6%), K880-1 (37.7%), Golestan® (33.3%), and the highest lint percentage were in a group. In terms of average boll weights in tested treatments, the combined variance analysis of two years was N2G80 with 176.3 g and M13 was the most light weight boll with 138.6 g. Early maturity in the GT40 genotype was 91.3%. While the SKT133 genotype was 34.3% (Table 1,2 ).
There was a signi cant difference between the mean of infestation to the population of green aphid in tested treatments with compound analysis of variance during two years of experiment. In SKT-133 and TBL-60 cultivars there were 27.15 and 29.11, respectively, in aphid with the least aphid and K880-2 cultivars and Golestan cultivar had the highest population with 48.85 and 46.31 aphid/leaf, respectively (Table 3). There was a signi cant difference between the treatments in terms of the average infestation rate of white y cotton in the treatments with combined analysis of variance during two years of experiment. The N2G80 and TBL-60 cultivars with 40.05 and 51.18, respectively, were lowest white y in the leaf and the BKW30 and K880-2 cultivars were 90.76 and 68.86, respectively, in the leaves with the highest white y (Table 3, Fig. 2).
Correlation coe cient between traits was equal to 0.55. The number of bolls per plant was not correlated with other traits including boll weight, lint percentage, aphid and white y. The correlation between the number of bolls and prematurely was very small and equal to 0.08. The correlation coe cient of the weight of the boll with lint percentage was 0.68. The population was positively correlated with the white y (0.47). The correlation between aphid and white y was positive and negative (-0.62). There was a positive correlation between the populations of the aphid and the yield of 0.50. Between the yield value and the early mature correlation, equal was 0.21 (Table 4).    cultivars and lines in Pakistani province for pest resistance morphological characteristics and it came to the conclusion that the earliness in the cultivars makes it possible to escape from the attack on the end of the White y and bollworm. (Kosas, etal., 2006), studying the preference of cotton aphids on six cotton cultivars in Greece. The results showed that Eva cultivar had a high trichome density on leaf with a population of 58-62 aphids in leaf and Zeta-2 with the least trichome density on the leaf population of aphid, 29-33 aphids per leaf had the lowest aphid population. Therefore, the cultivars bearing N2G80, TBL-60 and SKT-133 in this project had the lowest population of infestation with important sucking pests (thrips, aphids and white y ) and, on the other hand, they had a good yield and early maturity, which could be used in the future for the release of new Varity or in the production of new hybrids. The genotypes NHH44, LK861, Supriya, RS2013 and LD694 were categorized as moderately resistant in Population dynamic of Ahis gossypii (Glove.) on Genotypes