Comparative Demography of the Spider Mite, Oligonychus afrasiaticus, on four Date Palm Varieties in Southwestern Tunisia

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of palm date fruits. Life cycle, fecundity, and longevity of this mite were studied on fruits of four date palms, Phoenix dactylifera L. (Arecales: Arecaceae)(varieties: Deglet Noor, Alig, Kentichi, and Besser), under laboratory conditions at 27 = 1 °C, 60 ± 10% RH. Total development time of immature female was shorter on Deglet Noor fruits than on the other cultivars. O. afrasiaticus on Deglet Noor had the highest total fecundity per female, while low fecundity values occurred on Besser. The comparison of intrinsic rates of natural increase (rm), net reproductive rates (Ro), and the survival rates of immature stage of O. afrasiaticus on the host plants suggests that O. afrasiaticus performs better on Deglet Noor fruits. The mite feeding on Alig showed the lowest intrinsic rate of natural population increase (rm = 0.103 day 1). The estimation of difference in susceptibility of cultivars to O. afrasiaticus is crucial for developing efficient pest control programs. Indeed, less susceptible cultivars can either be left unsprayed or sprayed at low threshold

Essential oil from Tunisian Lamiaceae as crop germination inhibitors

The essential oil obtained from rosemary (Rosmarinus officinalis L.) and pennyroyal (Mentha pulegium L.) have been analyzed by GCMS and tested for their allelopathic properties on the seed of two crops (Raphanus sativus L. and Lactuca sativa L.), with the aim to evaluate in vitro their potential as germination inhibitors. The essential oil composition varied with the species, 1,8-cineole (26%) and camphor (23%) being the main constituents of rosemary and pulegone (45%) that of mint. This latest essential oil inhibited completely the germination of crops. The oil of rosemary inhibited completely the germination of Lactuca and showed for Raphanus germination values that were not significantly different from the contro

Corrosion performance of reinforced mortar in the presence of polymeric nano-aggregates: Electrochemical behavior, surface analysis, and properties of the steel/cement paste interface

This study reports on the effect of admixed polyethylene oxide-b-polystyrene (PEO113-b-PS70)micelles on corrosion behavior of reinforced mortar. The electrochemical measurement shows that the corrosion performance of the reinforcing steel was not significantly improved. However, surface analysis and microstructural investigation at the steel/cement paste interface reveal that the admixed micelles lead to a steel surface layer with enhanced barrier properties in terms of morphology and composition. Therefore, the presence of micelles further minimized and halted the corrosion process, despite the very aggressive, chloride-containing environment of 5% NaCl. The reasons and mechanisms behind the hereby observed corrosion behavior of reinforced mortar in the presence of micelles are related to the influence of these nano-aggregates on microstructural properties. These further results in altered water/ion transport and chloride-binding mechanisms in the bulk mortar matrix and thus steel product layer modifications towards enhanced corrosion resistance.Structural EngineeringCivil Engineering and Geoscience