الفهرس 
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Abstract
Cotton, Gossypium barbadence L., known as ”white gold”, is still considered one of the most important economical crops in Egypt. The cotton plants are susceptible to infestation by several insect pest species during all different stages of their growth. The low yield of cotton is caused by many factors, but the most serious ones are mainly related to the damage in green bolls caused by the cotton bollworms; the pink bollworm (PBW), Pectinophora gossypiella (Saunders) and the spiny bollworm (SBW), Earias insulana (Boisd.). The main method for controlling the cotton pests in Egypt, especially the bollworms is still by using chemical pesticides. Therefore, there is a mounting need to develop alternate, non-chemical tools, economical and environmentally friendly methods to suppress such pest’s infestation to cotton. Among non-polluting insect management methods, mating disruption technique and biological control through parasitoids alone have been successfully demonstrated in Egypt. Field experiments were carried out to study the population fluctuations and non-chemical control (mating disruption technique and releasing the egg-parasitoid, Trichogrammatoidea bactrae Nagaraja) of the two cotton bollworms; PBW and SBW at Elwan district, Assuit Governorate (Upper Egypt), for two successive cotton growing seasons, 2013 and 2014. In addition, this study also aimed to evaluate the performance of the parasitoid, T. bactrae when reared on eggs of different hosts under laboratory conditions. As well, the morphological changes on the sensory organs of this parasitoid species when switching the rearing host to alternative ones, using scanning electron microscopy (SEM), were investigated. The obtained results could be summarized as follows: A- Ecological studies 1- Population fluctuations of the cotton bollworms Population fluctuation studies of the two cotton bollworms, started from June to October throughout the two seasons of study, based on number of male moths captured by the sex pheromone baited traps and with referring to the phenology of the cotton plant and main weather factors. Besides, cotton bolls’ infestation rates by both bollworms were determined. The seasonal population showed 5 peaks of the both pests during the first season 2013, increased to 7 and 6 peaks for PBW and SBW, respectively in season 2014. The highest captured rates of both cotton bollworms were recorded in September and October, which coincided with the highest numbers of green bolls throughout the two seasons. 1.1. Effect of certain factors on population fluctuations of the cotton bollworms The relationship between the fluctuations in numbers of both captured moths versus the plant age, together with some prevailed weather factors through the 2 cotton seasons, 2013 and 2014 was studied. The independent variables were: plant age, temperature (maximum and minimum), relative humidity % (max. and min.), soil temperature at a depth of 5 cm (max. and min.) and wind (speed and direction). The statistical analysis of data revealed that the plant age was the most important factor affecting attraction of both pests and alone was responsible for more than 50% of the variability of the populations of the pests in the two seasons. The common ranks of the independent variables on the fluctuation of both bollworms seemed to be as follows: for PBW (plant age (23.39%), max. soil temp. in 5cm depth (6.06%), min. temp. (4.34%), min. RH% (4.29%) and finally min. soil temp. in 5cm depth (1.98%)), while for SBW (plant age (49.21%), max. RH% (4.55%), max. temp. (2.70%), min. temp. (2.32%), min. soil temp. in 5cm depth (1.80%) and finally max. soil temp. (1.01%)). However, relative impact of the wind had minimal effects on both moths’ attraction. 1.2. Percentage of infestation in the green bolls The results revealed that the infestation % with PBW in green bolls started by late June, increased gradually, and then sharply from early August up to the end of the season (October). For SBW, the infestation started in late August in 2013 and late July in 2014 and steadily increased to the 2nd week of September, then decreased when the majority of the bolls were opened. Moreover, the relationships between boll infestation and numbers of larvae were observed simultaneously, especially by late season. This means that as the infestation level increased, the number of larvae was exponentially increased. The highest % of infestation in cotton green bolls with both pests was recorded in August and September in both seasons. The use of pheromone trap data can be vital for early warning of the population incidence and prediction only but it is not sufficient to rely on control program without inspection of green bolls and determine the infestation level. Therefore, it is necessary to correlate trap inspections with green boll numbers and infestation. 2- Non-chemical control of the cotton bollworms in cotton fields The non-chemical control measures included were: behavioral control (mating disruption technique) and biological control (utilization of the egg parasitoid, T. bactrae, as a bio-control agent). 2.1. Mating disruption technique (PB-Rope) Effect of mating disruption technique, at the rate of 300 PB-Rope dispensers/ feddan for suppressing the population and percentage of infestation with PBW & SBW in cotton fields during 50% flowering growth stage was investigated. 2.1.1. Population monitoring (Trap catches) Number of captured moths in the sex pheromone traps was much lower in the pheromone-treated area as compared to that in the control field, in both seasons. Subsequently, the % of disruption was near to 100%. Season 2013: Just before installation of PB-Rope dispensers (sex pheromones of P. gossypiella), the number of PBW moths caught in the trap was much higher than that in the untreated field (control). In treating field, captures were suppressed totally (100%), starting the 1st week of July (4-days post treatment) till the 2nd week of September (71-days post treatment). Then, catches gradually appeared till the end of the season, but the numbers continued to be lower than that in the untreated fields. For SBW, the first appearance of male moths in the trap was by mid-August (late of the season) (46-days post treatment), with the same rate (4.00 males/trap) in both treated and untreated areas. Numbers of moths in the treated area sharply increased in the 2nd week of September (71-days after treatment) as compared to the untreated. Afterward, the number fluctuated and became lower than that observed in the control till the end of the season. Season 2014: The numbers of moths caught in the trap during this season were lower than that of the first one. Before applying the dispensers, the first number of PBW moths was similar (4.00 males/trap) in both areas. After 4-days of treatment (on June, 26th), number of moths caught was zero up to harvest time (by mid-September, 18th) (87-days post treatment) as compared to untreated areas. Then, the traps started to catch some moths after harvesting but with very low numbers in comparison with the untreated, which remained relatively higher. On the other hand, for SBW, the number of moths in the pheromone treated area was similar somewhat to the control until the 1st week of August, 7th (46-days after treatment). Then, the number of moths in the treated area increased till the 1st week of September (77-days after treatment). After harvesting by mid-September, the number fluctuated and became lower than that in the untreated one till the end of the season. 2.1.2. Infestation level Infestation rate of the cotton green bolls before applying the pheromone dispensers was (2.66%) in the first season, 2013 and was relatively higher (5.33%) in the second one, 2014 as compared to those in the untreated area (4%) in both seasons. In the treated area, % of infested bolls significantly decreased recording zero for 6 weeks, representing (100%) reduction in the infestation in both seasons. After this time, the infestation occurred, but at a very low level in the treated area only. By early-September, the majority of bolls opened and infestation rate was (<10%) in 2013 as compared to those of untreated field (49 %) by the end of this season. However, the infestation % in 2014 remained for 3 weeks in the untreated area only. Obtained results indicated that when PB-Rope dispensers were applied during the 50% flowering growth stage, the % of disruption in both seasons was nearly (100%) and significantly reduced the infestation rates with PBW in green bolls until the end of the season (harvesting). On the other hand, for SBW, although insignificant differences were noted between the mean numbers of male moths in the pheromone-treated area and that in the control, but the infestation level in green bolls was significantly decreased as compared to control area. This may be related to the competitive behavior between PBW and SBW as the presence of a huge amount of synthetic sex pheromone emitted from the dispensers into a crop and the atmosphere that led to dispersal of this pest to alternative hosts. This study suggests that using only one application of pheromone dispenser, early during the flowering growth stage (50%) of the cotton plants was sufficient to maintain the moth catches and infestation % in green bolls at the lowest level as compared to the untreated area. Subsequently, farmers don’t need to apply insecticides to suppress the infestation. 2.2. Biological control This study aimed to find out the most proper timing of releasing the egg parasitoid, T. bactrae (50% flowering and boll formation growth stages), and different rates of releases (1-4 releases) for suppressing the populations of both PBW and SBW. Season 2013: Just a pre-release of this parasitoid, the percentage of infested bolls with PBW was (4 and 3%) in the control and the experimental areas, respectively. In contrast, for SBW, no infestation was observed in both areas. On both dates of application, the rate of infested bolls increased towards the end of the season (harvest time) reaching its maximum in September. However, it was low as compared to the untreated for both pests in all releases; indicating that the parasitoid succeeded to suppress the infestation rate. Generally, bollworm’s infestation at the late season (August-September) was much higher than that in the early season (June-July). Based on obtaining results, the 4-releases of T. bactrae were able to reduce the total percentage of bollworms infestation than control with about (58.18 and 56.53%) during the two application dates, respectively. Additionally, releases of the parasitoid at the boll-formation growth stage showed an increasing role against SBW than PBW. Season 2014: The percentage of infestation with both of PBW and SBW during this cotton season was much lower than that recorded in 2013. Pre-releasing the parasitoid, the % of infested bolls with PBW was (4 and 2.67%) in the control and the experimental areas, respectively. On the contrary, no infestation was observed in both areas with SBW. The highest infestation rate by both pests in the green bolls, during this season, was recorded in all treatments in August, with different rates. It was obvious that 4-releases of T. bactrae, when applied at the (50%) flowering growth stage) succeeded to reduce the total percentage of bollworms infestation than control with (91.64%), opposed to (80.26%) during the boll formation growth stage throughout the whole period of the season. Also, the results proved that release timing of the parasitoid showed an efficient role against SBW than PBW, when compared to control. This may be attributed to the presence of okra plants (major host plant) in the adjacent areas that increases the infestation rate of SBW in this season. Obtained results revealed that different rates of releases at the two different application dates showed a significant reduction in % of infestation in green bolls; (12.54 to 66.36 and 43.74 to 90.03%) with PBW and (18.95 to 62.51 and 59.1 to 93.25%) with SBW, as compared to the control in 2013 and 2014 seasons, respectively. Moreover, 4-releases early, at 50% flowering growth stage, suppressed the infestation with PBW by (66.36 and 90.03%) in the two seasons, respectively. For SBW, the 4-releases caused a higher reduction in the infestation in the 2nd season (93.25%), opposed to (50%) in the 1st one. In conclusion, the egg parasitoid, T. bactrae can successfully be used as a biological control agent against the two pests in cotton fields in Upper Egypt. Furthermore, releasing of this parasitoid, 4 times early during the cotton flowering growth stage, is recommended. The use of this parasitoid was <50% less cost than the insecticide applications when both control methods were compared. 3- Cotton production and cotton boll weight At the end of each season, the cotton yield per feddan at different treatments (mating disruption technique, releases of T. bactrae) versus control (untreated area) was determined. Obtained results indicated that the mean cotton production (Kentar)/feddan can be arranged in a descending order as follows: PB-rope pheromone (10.25) > releases of the parasitoid at 50% flowering growth stage (9.75) > releases of the parasitoid at boll formation growth stage (8.62) > control (6.37). Additionally, the average weight of cotton bolls at each treatment showed that both in the control (1.999 gm) and in one parasitoid release (2.075 gm) during the boll formation stage had the lowest weight of cotton boll as compared to the rest of the treatments that ranged between (2.428-2.996 gm). The 4-releases of parasitoid, early through the flowering growth stage, achieved the best results in reducing the % of pest infestation and high yield. B- Laboratory Studies 1- Performance of T. bactrae in eggs of different insect hosts This study aimed to evaluate host preference and the effect of the host species on the performance of the egg-parasitoid, T. bactrae, when reared on eggs of four different lepidopterous hosts; Sitotroga cerealella; Corcyra cephalonica; Spodoptera littoralis (without & with dense scales) and Pectinophora gossypiella in a no-choice test. The biological parameters estimated were: parasitism %, adult emergence % and sex ratio (female %). The data proved that shifting of the T. bactrae, reared for successive generations on S. cerealella eggs, was able to parasitize the eggs of all tested hosts, but with different rates. Moreover, the host eggs of P. gossypiella, followed by S. cerealella were the most preferable ones, while S. littoralis (with dense scales) was the last. 2- Morphological and Ultra-structural studies of the egg-parasitoid, T. bactrae This study aimed to describe the diversity, morphology and ultra-structure of the sensilla distributed in different parts (antennae, eyes and wings) of both male and female of the egg-parasitoid, T. bactrae, reared on the previous 4 different egg host species, using scanning electron microscopy (SEM) in Assuit University. This is maybe the first study that dealt with the morphology, abundance and distribution of sensilla in both sexes of this parasitoid species, when reared on different egg hosts. 2.1. Antennae The antenna of T. bactrae, reared on different egg hosts, were very similar in terms of their general structure to those of other Trichogramma species and to others parasitic Hymenopteran species, which composed of basic 3 segments (Scape with a basal radicle; pedicel and segmented distal flagellum). The flagellum was the most important segment of the antenna that showed strongly sexually dimorphic. Insignificant changes appeared in the mean antennal lengths between males and females in all examined egg hosts, with only one exception of C. cephalonica reared eggs. Based on rearing parasitoid on different egg hosts, only the males’ antenna was varied significantly. 2.1.1. Different types of antennal sensilla All the antennal segments were covered by different types of sensilla in both sexes of the tested specimens. Moreover, the club segment (clava) had the most sensillar types, regardless of the sex and the rearing egg host. Based on the morphological features of each type of sensilla, there were 8 groups observed in males and divided them into different subtypes (19 subtypes). The main types were: Sensilla ampullacea (Am), basiconic sensilla (BS I-III), basiconic capitate peg sensilla (BCPS I-II), campaniform sensilla (Ca), chaetica sensilla (Ch I-V), coeloconic sensilla (Co), placoid sensilla (PL I-II) and trichoid sensilla (Tr II, IV-VI). Moreover, in females, 10 groups of sensilla were categorized into (21 subtypes) plus setae (S) were observed. Those sensilla were: Sensilla ampullacea (Am), basiconic sensilla (BS I-IV), basiconic capitate peg sensilla (BCPS I), campaniform sensilla (Ca), chaetica sensilla (Ch I-V), coeloconic sensilla (Co), falcate sensilla (FS), placoid sensilla (PL I-II), styloconic sensilla (St) and trichoid (Tr I-III, V). The different subtypes, arrangement, places and numbers varied among individuals after shifting the rearing egg host. 2.2. Compound eyes The head had two large compound eyes with oval-shaped, composed of aggregation of large numbers of visual elements called ommatidia. The current study, revealed a remarkable variation in the morphological parameters between males and females in all examined hosts, also between eye length of female individuals and width of males in response to rear on different eggs. Further, female’s eyes tended to be larger and wider than those of males in all egg hosts. 2.2.1. Compound eyes sensillar types Different types of sensilla were recognized in the compound eyes of males and females parasitoid after changing the rearing eggs. Sensillae basiconic (BS) were densely distributed irregularly with different subtypes in all examined specimens associated with the sex and the rearing egg host. In addition, the campaniform (Ca) and coeloconic (Co) sensilla were apparently observed in all examined hosts with obvious variations in their numbers, not only between males and females, but also among individuals switched the rearing egg host. Trichoid sensilla (Tr) type (I) was the least abundant sensillar type observed only when females were reared on eggs of S. littoralis either (without or with dense scales). 2.3. Wing According to rearing T. bactrae on different egg hosts in this study, insignificant variations were recorded in the morphometric of wings (length and width) between the sexes. However, significant differences were observed in wing lengths only within the same sex associated with the reared host. The present study also pointed out the different types of sensilla on the wings in males and females of all examined eggs. In addition, the different subtypes of trichoid (Tr) sensilla appeared on the 1st row of the costal margin (the edge), were increased in males than females in response to the change of the rearing eggs, and this may be due to the main role of males in courtship and mating behavior. Also, Tr (I, II) only was in the 2nd row and was the same in both sexes, regardless of the rearing host. Besides, trichoid sharp sensilla (TrS) were arranged partially in rows all over the wing at all tested eggs. Campaniform (Ca) sensilla were scattered irregularly on the wing surface of the parasitoid, regardless of the sex and the egg host, but with different numbers. The numbers of (Ca) increased apparently in females rather than in males of all rearing hosts, except S. littoralis eggs (with dense scales); males had much more (Ca) than females. Sensilla coeloconic (Co) were also observed on the wing surface of both sexes at all examined eggs.