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  • Author or Editor: G. A. Evans x
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Species of the family Signiphoridae (Chalcidoidea) are primarily hyperparasitoids associated with scale insects, whiteflies and mealybugs through other Chalcidoidea; however, certain species are primary parasitoids of these hosts. Recent collections and a review of the literature indicate that the following five species of the family Signiphoridae are known to occur in Egypt: Chartocerus niger (Ashmead), Chartocerus subaeneus (Főrster), Signiphora fax Girault, Thysanus sp. and Signiphora flavella Girault, the latter newly recorded in Egypt and Palearctic region. A key to the Egyptian signiphorid species is included.

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Blepyrus insularis (Cameron) (Encyrtidae) was reared from Phenacoccus parvus Morrison, an invasive mealybug recently found infesting Psidium sp. in Egypt. Encarsia cibcensis Lopez-Avila (Aphelinidae) was reared from Aleuroclava psidii (Singh) (Hemiptera: Aleyrodidae), an invasive whitefly found on Ficus sp. in Egypt. Mesopeltita truncatipennis (Waterston) (Pteromalidae) was reared from the lecanodiaspid scale, Lecanodiaspis africana (Newstead) (Hemiptera: Lecanodiaspididae) on Ficus sp. All of these represent new host records for the parasitoids.

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Authors: G. Evans, W. Kupferschmidt, R. Portman, A. Palson and G. Sanipelli


The environmental impact of many postulated CANDU (Canada Deuterium Uranium) reactor accidents depends on the behaviour of iodine isotopes. In recent years a substantial portion of Canadian iodine research has focused on experiments conducted in the intermediatescale Radioiodine Test Facility (RFT) at Whiteshell Laboratories. Because of the very low concentrations relevant to reactor accidents, much of the analysis of iodine behaviour has required the high sensitivity of a radiochemical methodology. Very low gas-phase iodine concentrations (<10–10 mol/dm3) are routinely determined, up to several times an hour, using an automated airborne iodine sampler whereas various chemical forms are distinguished using selective adsorbents. Useful information regarding the chemical speciation of iodine in the aqueous phase is obtained using solvent extraction. This paper describes the radiochemical techniques used in RTF experiments, with examples of the results thereby obtained.

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The mango shield scale, Milviscutulus mangiferae (Green) (Hemiptera: Coccidae), a serious pest of mango trees in various parts of the world, is reported on Mangifera indica in Egypt which represents the first record of this species in the country.

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Authors: P. Warwick, N. Evans, A. Hall, G. Walker and E. Steigleder


Conditional stability constants have been determined for U(IV) and U(VI) Boom Clay humic acid (BCHA) and Aldrich humic acid (AHA) complexes, under anaerobic and carbonate free conditions. The constants are needed for nuclear waste repository performance assessment purposes. The U(IV) constants were obtained by developing an approach based on the solubility product of amorphous U(OH)4. The U(VI) constants were obtained by applying the Schubert ion-exchange approach.

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Authors: Elizabeth C. Cropper, C. G. Evans, J. Jing, A. Klein, A. Proekt, A. Romero and S. C. Rosen

Although feeding in Aplysia is mediated by a central pattern generator (CPG), the activity of this CPG is modified by afferent input. To determine how afferent activity produces the widespread changes in motor programs that are necessary if behavior is to be modified, we have studied two classes of feeding sensory neurons. We have shown that afferent-induced changes in activity are widespread because sensory neurons make a number of synaptic connections. For example, sensory neurons make monosynaptic excitatory connections with feeding motor neurons. Sensori-motor transmission is, however, regulated so that changes in the periphery do not disrupt ongoing activity. This results from the fact that sensory neurons are also electrically coupled to feeding interneurons. During motor programs sensory neurons are, therefore, rhythmically depolarized via central input. These changes in membrane potential profoundly affect sensori-motor transmission. For example, changes in membrane potential alter spike propagation in sensory neurons so that spikes are only actively transmitted to particular output regions when it is behaviorally appropriate. To summarize, afferent activity alters motor output because sensory neurons make direct contact with motor neurons. Sensori-motor transmission is, however, centrally regulated so that changes in the periphery alter motor programs in a phase-dependent manner.

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