الفهرس 
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Abstract
The red palm weevil, Rhynchophorus ferrugineus (Oliv., 1760) (Coleoptera: Curculionidae) is the major destructive pest for several palms in different countries. The establishment of R. ferrugineus in Egypt was confirmed at the end of November 1992. Information on the histology or ultrastructure of the internal organs of this pest including the gonads (ovary & testis) or about the gametogenesis is not available. Such information might be valuable in finding a suitable insecticide against this red palm weevil. Therefore, it was the aim of the present research to study the anatomy, histology and ultrastructure of the main genital organs of the red palm weevil, and to investigate the pathogenicity of different concentrations of a natural plant extract (neem) and a synthetic insect growth regulators (IGRs) (flufenoxuron) on the histology of the ovary and testis, the ultrastructure of testis and on some biological parameters of the red palm weevil. Prepupae of the red palm weevil were collected from infested date palm trees at AlManaief AlGharbia region, Ismaileya governorate. The prepupae were divided into seven groups; the first was the control group and treated only with the vehicle. Prepupae of the 3 next groups were treated with 3 different doses of neem extract (Neem J, 50, 100, 500 ppm). The last 3 groups were treated similarly with a synthetic insect growth regulator (flufenoxuron, 0.05, 0.1, 0.5 ppm). All treatments were undertaken by exposure of the prepupae from the different groups individually and topically to the different substances. Prepupae of the different groups were reared on portions of fresh sugarcane stem tissue in the laboratory. Samples were followed daily to observe different biological parameters such as mortality, inhibition of metamorphosis, pupation place and percentage, morphologic aberrations and percentage of adult emergence. After emergence, Adult samples were dissected out to examine the reproductive system. Ovaries and testes were processed for histological and ultrastructural examinations. The results are the following: Mortality of prepupae, pupae and adults of R. ferrugineus treated with neem extract increased with the increase of neem dose. Neem application significantly reduced the pupation period of the red palm weevil. This pupation period was inversely related the neem dose. The sex ratio was directed toward the female side, indicating that neem affected males more than females during their growing. However, this effect was not increasing with the increase of neem dose. In comparison to controls, both male and female adult weevils were significantly shorter in body length after neem application. The lethal effect of flufenoxuron was more obvious in the pupal stage than the prepupae or the emerged adults. The highest dose (0.5 ppm) was able to kill 46.2% of the total pupae. Not all flufenoxurontreated prepupae have pupated in a cocoon. This effect was concentrationdependent. Also, flufenoxuron significantly reduced the pupation period of the red palm weevil in a dosedependent manner. After flufenoxuron treatment, sex ratio was directed toward the female side an effect that was also dosedependent. A significant dosedependent reduction in body lengths of both sexes was observed after application of flufenoxuron. The female reproductive system of R. ferrugineus has paired ovaries. Each ovary is consisted of a pair of ovarioles. Both ovarioles are connected to an oviduct, which fuses with the other forming a common oviduct followed by a vagina. A spermatheca opens at the anterior part of the vagina, where an accessory gland is also found. Each ovariole contained a linear series of oocytes in successive maturation stages. It could be histologically differentiated into three portions according to the developmental stages of the oocytes: germarium with oogonia, vitellarium with nurse or trophocyte follicles and pedicel with mature ova. One or both of the used IGRs can be used in the control of the red palm weevil. However, further studies are required to elucidate the exact mechanisms involved in this IGRsinduced toxicity.