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This work proposes a simple method to enhance amplitude stability in Pierce crystal oscillator. The method is based on a modification of the conventional Pierce oscillator. The pro- posed topology is all-analog, yet it does not use an amplifier-based feedback loop for amplitude control, hence, it saves power, reduces complexity, and layout area. The proposed method does not adversely impact oscillator's phase noise, and gives good amplitude control results against process, voltage, and temperature (PVT) variations. An example design for a 40 MHz Pierce crystal oscillator is implemented in a standard 0.13 μm CMOS technology and compared to conventional Pierce oscillator results. The current consumption of the oscillator core is 500 μA off 1.2 V supply. The proposed method is extensible to other CMOS VCOs, including Giga-Hertz ones, to reduce design margins on VCO gain. [ABSTRACT FROM PUBLISHER]

Spectral characterization of four crude oils was attempted by using a different approach for time-resolved laser-induced fluorescence (TRF) techniques. The TRF spectra were excited by pulsed UV laser radiation at 250 nm and were measured at specific time windows of equal gate widths along the trailing edge of the pulsed laser. Contour diagrams of equal fluorescence intensities were then constructed to serve as unique fingerprints for the crude oils. The method does not require that the laser pulse be deconvoluted from the fluorescence signal, which makes it attractive for remote characterization of crude oil.

Eggs and larvae of Microplitis rufiventrisKok. (Braconidae: Hymenoptera) were exposed to two sublethal concentrations (0.2 and 0.4 ppm) of the chitin synthesis inhibitor lefenuron, by feeding treated artificial diet to their hosts, Spodoptera littoralis(Boisd.) (Noctuidae: Lepidoptera) larvae. Each concentration was initiated during the egg stage or different instars of the parasitoid larvae. Between 4.3 and 33.8% of parasitoid larvae in lefenuron-treated hosts showed morphological and developmental abnormalities. The effect of the compound on the developmental rate and sensitivity of the parasitoid larvae varied according to the parasitoids’ age at treatment; the egg stage and older parasitoid larvae were more tolerant to the compound than the first instars. In all treated hosts the developmental rate of the parasitoid was lower than that of controls. The lower lefenuron concentration (0.2 ppm) was more effective at disrupting the development of young parasitoid larvae than the higher one. Delayed or latent effects of the compound were evident in non-emergence of parasitoid adults that were exposed to the compound as first instars. Reduced sensitivity of old parasitoid larvae could be compatible with survival of the parasitoid in integrated control programme of S. littoralis. Les oeufs et larves de Microplitis rufiventrisKok. (Hymenoptera: Braconidae) étaient exposés á deux concentrations sub-létales (0,2 et 0,4 ppm) de lefénuron, un inhibiteur de synthèse de la chitin, par alimentation sur milieu artificiel des chenilles de Spodoptera littoralis(Boisd.) (Lepidoptera: Noctuidae) qui sont des hôtes du braconidé. Chaque dose était administrée au stade oeuf ou á des différents stades larvaires du parasitoïde. Les chenilles nourries au lefénuron ont révélé entre 4,3 et 33,8% de larves mal développées du parasitoïde et possédant des anomalies morphologiques. L’effet du lefénuron sur le taux de croissance et de développement ainsi que sur la sensibilité des larves variaient avec l’âge du parasitoïde, au moment du traitement. Les oeufs et larves âgées du parasitoïde étaient plus tolérants vis-á-vis du produit plus que les jeunes stades. La basses concentration du lefénuron pertubait le développement des jeunes larves plus que les concentrations élevées. L’arrière-effet et la latence du produit étaient manifestes et ils étaient reflétés par la non-émergence des adultes chez les larves exposées au produit á leur premier stade de développement. Dans un programme de lutte intégrée contre S. littoralis, une sensibilité réduite des larves âgées du parasitoïde pourrait présager une survie du parasitoïde.

Rates of virus-induced mortality and values of the LC50and LT50showed that, in general, parasitism by Microptitis rufiventrisKok. increased the susceptibility of the Egyptian cotton leafworm, Spodoptera littoralissecond-instar larvae to its nuclear polyhedrosis virus (SLNPV). By comparing the LC50values, data revealed that virus-infected parasitized larvae were ca. 3.5 and 4.8 times more susceptible to SLNPV than virus-infected unparasitized ones at 8 and 12 days post-infection, respectively. Also, in virus-infected unparasitized larvae, the time required to attain a 50% mortality was significantly longer than that in virus-infected parasitized ones. Virus-induirés mort (%) et les valeurs de LC50et LT50révélé que parasitism par Microplitis rufiventrisKok. augmenta le sensible d’une feuille de coton égyptien, Spodoptera littoralisII - stade larvés au le noyau polyhedrosé virus (NPV). Les valeurs de LC50ont révélé que virus - infectés parasitiés larvés était plus sensible 3.5 et 4.8 fois que les virus - infectés non-parasitiés larvés après 8 et 12 jours d’infection respectivement. Aussi, pour les virus - infectés non-parasitiés larvés, la valeur de LT50était significantly longuer que les virus-infectes parasitiés larvés.

The chitin synthesis inhibitor lefenuron [N-(2,5-dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoropropoxy)-phenylaminocarbonyl-2,6-difluorobenzamide] was found to have a negative effect on the encapsulation responses of Spodoptera littoralislarvae towards supernumeraries of Microplitis rufiventrisparasitoid. Superparasitised hosts fed on compound-free diet showed strong encapsulation reaction (ca. 40.8%) to surplus parasitoid larvae having scars of physical combat. Treated hosts exhibited a significant reduction in either capsule thickness or encapsulation rate to the excess parasitoid larvae. Even when a capsule was formed, it had a thinner haemocy tic layer than tha t of control hosts. Studies on the differential haemocyte counts showed that failure of treated larvae to encapsulate injured surplus parasitoid larvae could be attributed to the following factors: (1) disturbance in plasmatocytes-granular cells (GR) ratio, e.g. abnormal increase in GR levels possibly causing faint haemocytic reaction to injured parasitoid larva(e); (2) the parasitoid surface becoming less attractive to the granulocytes and plasmatocytes; (3) the haemocytes involved in capsule formation (granulocytes, plasmatocytes) losing their ability to spread out over the surface of parasitoid larvae; and (4) the blood cells of the treated host failing to recognise wounded larvae as foreign bodies. Reduced encapsulation capacity might be due to a secondary effect(s) of IGR treatment inducing a suppression of adhesive activity of the plasmatocytes. These results may be useful for improving our understanding of insect immune reaction and/or manipulating parasitoids activity against nonhabitual Parasitoida. Il a été observée que l’inhibiteur de synthèse de la chitine—le lefenuron [N-(2,5 dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoroprópoxy)-phenylaminocarbonyl)-2,6 difluorobénzamide], comportait un effet négatif sur les réponses des larves de S. littoralis, à encapsuler les larves surnuméraires issues du superparasitisme par le parasitoïde Microplitis rufiventris. Les larves hôtes superparasitées et nourries sur un milieu sans cet inhibiteur montraient une forte réaction d’encapsuler le surplus de larves (environ 48%) du parasitoïde, qui avaient des cicatrices résultant d’un combat physique. Chez les hôtes traités on a observé une réduction importante, soit de l’épaisseur de la capsule ou du taux d’encapsulation des larves excédentaires du parasitoïde. Même si une capsule était formée, celle-ci était caractérisée par une mince couche d’hémocytes en comparaison de celle des témoins. Les comptages différentiels d’hémocytes ont montré que l’échec des larves traitées à encapsuler les larves blessées excédentaires du parasitoïde pourrait être attribué aux facteurs suivants: (1) un déséquilibre du rapport entre plasmatocytes et granulocytes c-à-d une augmentation excessive du nombre de granulocytes, qui probablement débouche sur une faible réaction des hémocytes chez les larves blessées du parasitoïde; (2) la paroi corporelle du parasitoïde devient moins attrayante pour les granulocytes et les plasmatocytes; (3) les hémocytes (granulocytes, plasmatocytes) intervenant dans la formation de la capsule perdent leur pouvoir de couvrir la paroi corporelle du parasitoïde; et enfin, (4) les cellules sanguines de l’hôte traité sont incapables de reconnaître les larves blessées comme des corps étrangers. La capacité réduite d’encapsulation peut résulter des effets secondaires de régulation de la croissance de l’insecte due à l’inhibiteur qui annule l’activité adhesive des plasmatocytes. Ces résultats pourraient nous aider à mieux comprendre les mécanismes qui régissent la réaction immunitaire de l’insecte et/ou manipuler l’activité des parasitoïdes dans le sens d’éviter un parasitisme inhabituel au sein du groupe Parasitoida.

Abstract: The internal parasiteMicroplitis rufiventris Kok. passes through 3 instars but moults 3 times within its host. The last moult occuring just at emergence time. The morphology of the egg and larval stages of the parasite are discussed. At 27°C and a photoperiod of 6 h (6L:18D) the endo-developmental cycle of the parasite can summarize as follows: Egg 18–24 h; instar 1,4 days (fighting phase 48 h; feeding phase 30–48 h); instar 2, 12–18 h and instar 3,3 days. The effect of different photoperiods on the relative speeds of the endo-developmental stages of the parasite at each of 30, 25, 20°C were carefully studied. At the first 2 temperatures, the short photoperiod (6L:18D) accelerated the development of larval instars, while both of 18L:6D or 0L:24D slowed down the development. Under the latter photoperiods some larvae failed to moult and had emergence problems. The influence of photoperiod is significantly noticeable at 20°C. The incubation period of the egg-stage was prolonged significantly at 18L:6D and the development of larval instars was significantly faster and refined at 6L:18D. The factor(s) inhibiting the development of the egg-stage perhaps differ from those affecting the larval development. The ventral area of the host mid-gut among malpighian tubes seems to be where the surplus parasite larvae are eliminated by physical attack. A physiologically suppressed parasite larva is able to attack its developed competitor of the same age. Teratocytes cells perhaps play a part in eliminating the surplus parasite larvae by physiological suppression.

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2,13-octadecenyl acetate and (E,Z)-3,13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 ± 2.9 kg per tree) and 2007 (23 ± 1.3 kg per tree) compared with control ones (61.0 ± 3.9 and 10.0 ± 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.

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Different larval stages of Microplitis rufiventris Kokujev were exposed to a sublethal dosage (0.4 ppm) of Lefenuron [N-{2, 5-dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoropropoxy)-phenylaminocarbonyl}-2, 6-difluorobenzamide] or Lefenuron (0.2 ppm)/Deltanet (0.2 ppm) [O-n-butyl Ō-(2, 2-dimethyl-2, 3-dihydrobenzofuran-7-yl)-N, N'-dimethyl-N-N'-thiodicarbamate] by feeding treated artificial diets to parasitized Spodoptera littoralis (Boisduval) larvae to evaluate the effects on the reproductive potential of developing parasitoids. Lefenuron treatments caused a reduction in the reproductive ability of either the host insect or its parasitoid. Ovaries of parasitoid females (1 d old) emerging from Lefenuron/Deltanet treatments contained more ova than those from either Lefenuron-treated or control females. Experienced (ovipositing) females from Lefenuron/Deltanet treatments deposited significantly more eggs and contained, at death, more remaining mature oocytes in their calyx and egg reservoirs. The combination of a carbamate insecticide (Deltanet) and chitin-inhibiting growth regulator (Lefenuron) may enhance the reproductive ability of insect parasitoids and may provide a potential means for developing more effective biological control methods against insect pests.

The developmental history of Microplitis rufiventris Kokujev the parasite within singly parasitized hosts, Spodoptera littoralis (Boisduval), was compared with that in superparasitized hosts. Different levels of superparasitism had no effect on the length of the egg stage but caused changes in the lengths of the stadia of the surviving parasite and in the encapsulation ability of the host against the eliminated first-instar parasite. Larval development was faster in singly parasitized hosts and decreased with increasing superparasitism. The percentage of encapsulation of eliminated parasite larvae increased with increasing numbers of parasite progeny per host larva. The results suggest the existence of permanent and impermanent capsules, the latter detectable within heavily superparasitized hosts. Some of the surplus parasite progeny appear to be eliminated early by physiological suppression and others later by encapsulation. In singly parasitized hosts, a nontrivial number of parasite larvae died very early as a result of unspecified host immune response(s).

A general survey was made on the zoosaprophagous insects and their associates in a natural ecosystem in the Egyptian western desert (80 km west of Alexandria, 12 km from the Mediterranean Sea shore). Two types of traps were used, one for flying insects and the other for soil-burrowing insects. Two types of decaying media were used as baits: the common freshwater fish (Tilapia zilii Gerv.) and the desert snail (Eremina desertorum). More than 30 insect species were trapped. The following orders and families were represented: Diptera (Calliphoridae, Sarcophagidae, Muscidae); Coleoptera (Histeridae, Scarabaeidae, Dermestidae, Tenebrionidae); Hymenoptera (Chalcididae, Pteromalidae, Eulophidae, Formicidae). Monthly totals of numbers trapped in each of these groups are presented.