This study evaluated the efficacy of different cleaning methods with respect to changes in the color and light transmittance of both rough and smooth thermoformed, copolyester retainer specimens, after staining in different solutions. Four hundred copolyester sheets (Essix ACE) specimens were fabricated over molds with different surface textures, smooth and rough. The specimens were stained in four different solutions (n = 100 per solution) over 28 days; then, each of the four groups of 100 stained specimens was sub-divided into five groups of 20 specimens and subjected to a different destaining solution. The specimens were sub-divided with half subjected to an additional ultrasonic cleaning procedure. Light transmittance and color changes were analyzed using a spectrometer/integrating sphere assembly and a spectrophotometer. Mean difference comparisons were performed using appropriate statistical tests at p = 0.05. All five destaining solutions proved to be effective at removing coffee and tea stains. The surface roughness of the retainer material plays a significant role in the ability of cleaning solutions to remove stains, demonstrating a greater effect on cleaning rough specimens with respect to improvements in light transmittance and greater changes in color. Additionally, an ultrasonic cleaning unit generally enhanced the ability of all five solutions to clean the tea-stained specimens. However, the enhancements were only significant for light transmittance.

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect of maize, Zea mays L., but knowledge of its interaction with water deficit on maize production is lacking. A series of greenhouse experiments using three infestation levels of the western corn rootworm, D. virgifera virgifera, under well-watered, moderately dry, and very dry soil moisture levels were conducted to quantify the interaction of western corn rootworm and soil water deficit on B73×Mo17 maize growth and physiology. Three separate experiments were conducted. Soil moisture regimes were initiated 30 d postplanting for experiments using neonate and second-instar larvae and 30 d postinfestation in the experiment using eggs. In the neonate and second-instar experiments, there were no significant differences among western corn rootworm levels in their effects on leaf water potential, shoot dry weight, and root dry weight. The interaction of western corn rootworm and soil moisture significantly impacted the larval recovery in the neonate experiment, but no other significant interactions were documented between soil moisture levels and rootworm infestation levels. Overall, the results indicate that under the conditions of these experiments, the effect of water deficit was much greater on plants than the effect of western corn rootworm and that the interactions between water deficit and western corn rootworm levels minimally affected the measured parameters of plant performance.

This work was initiated for the first time to identify parasitoid species associated with the immature stages of Pieris rapae (L.) inhabiting cabbage plantations in Assiut governorate, Upper Egypt during the 2018 and 2019 cabbage growing seasons. Attacking periods and parasitism percentages (PPs) of the identified parasitoid species were calculated. One solitary parasitoid species, Hyposoter ebeninus was found to attack P. rapae larvae in the field 110 days after transplantation. However, one hyperparasitoid species Baryscapus galactopus was recorded as an internal gregarious hyperparasitoid of H. ebeninus. The solitary larval parasitoid H. ebeninus strikes were recorded throughout the last five weeks of the season with a marked decline before harvesting. Although H. ebeninus revealed 42.00% abundance, it presented 21.69% PP on P. rapae larvae during the entire period of study. One solitary, Brachymeria femorata and two gregarious parasitoid species [Pteromalus puparum (L) and Tetrastichus sp. (Haliday) were recorded as P. rapae pupae parasitoids on October, 2 nd . Parasitism peak was recorded on October, 16 th with an average of 56.25%. The first appearance of the gregarious pupal parasitoid P. puparum was recorded on October, 9 th . Four weeks later, the second gregarious parasitoid (Tetrastichus sp.) was recorded on November, 6 th . Both pupal gregarious parasitoid species were found to be active until harvesting. The gregarious parasitoid P. puparum presented high PP (23.73%) as compared with Tetrastichus sp. which exhibited 6.96% PP during the entire period of study. In conclusion, two solitaries, one hyperparasitoid, and two gregarious parasitoid species were identified. Pupal gregarious parasitoid species together reduced P. rapae pupae populations by 30.69%. These parasitoids could be used in the IPM programs for this pest in the future. At the same time, the effect of hyperparsitoides must be taken into consideration.

No abstract

This work was carried out at the experimental farm of the Faculty of Agriculture, Assiut University during the 2017-2018 and 2018-2019 cabbage growing seasons. Evaluation of the seasonal abundance of the cabbage aphid Brevicoryne brassicae L in cabbage fields and responsibility of certain biotic factors for managing populations of this insect pest was the cornerstone of this investigation. Cabbage aphid, B. brassicae was found to be active on cabbage plantations and recorded in low numbers (99.71 individuals / 12.5 Cm 2 / leaf / infested plant) at the beginnings of the season (November) with gradual increase until harvesting. Three amongst the six evaluated cabbage cultivars and/or hybrids were appeared as susceptible (S) and harbored so high numbers of the pest. However, the remaining cultivars showed some sort of resistance to this insect pest. The local cultivar (Ganzory) harbored the least aphid numbers and appeared as moderately resistant (MR) cultivar. This finding could be attributed to the antixenosis and/or antibiosis phenomena presented by this local cultivar. Proteins and amino acid contents showed a highly significant positive correlation (r) with B. brassicae populations, however, chlorophyll showed highly significant negative (r). The obtained data reflect the role of the cabbage aphid parasitoid Diaeretiella rapae (McIntosh) to manage B. brassicae populations. Mummified aphids (parasitism rate) before harvesting were found to be equal 6.16 fold of that recorded before ripening stages. High percentages of D. rapae were succeeded to emerge from the mummified B. brassicae with diverse extrusion rates. Multiple increases were recorded on the percentages of infested plants when cabbage undergo toward ripening at the 9 th stage till harvesting. No or less existence of unmarketable plants (through the periods of the low infestation) before cup formation and/or plant ripening period was recorded. So, it can be concluded that cabbage cultivar, plant age, and stage in addition to plant metabolites combined with the naturally occurring biological control agent (Aphid parasitoid) can be affected and manage the population trend of cabbage aphid B. brassicae infesting cabbage in the field.