Recently, the senior author discovered the presence of a whitefly on sugarcane,
, in Qena, Egypt, and sent specimens to the junior author who identified it as
Takahashi (Homoptera: Alyerodidae). Since this is the first report of this species occurring on sugarcane, an economic crop, and the first distribution record of it occurring in Egypt and the Mediterranean region, we thought it expedient to publicize the information to alert workers in the region to its presence.
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.
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.
In the light of the remarkable strides in radioactivation analysis methods and techniques that haved been achieved progressively in the 34 years since Modem Trends conferences began, some speculations on the future directions that the field might take in the foresceable future seem appropriate at MTAA-9. Together with improvements that will likely occur in instrumentation, in prompt and ion-beam methods, there would seem to be yet a further potential for extending the range of information that radioanalytical techniques can provide by complementing RAA measurements on samples with an increased use of manipulative chemistry. Among complementary chemical methods are not only pre-activation chemistry for speciation studies and matrix removal but also, radiotracer/INAA combinations, isotopic exchange/INAA (as illustrated in this paper through recent studies on the behavior in the environment of solid waste residues), substoichiometric-RAA and classical radiochemical, post-activation separations for specific element(s). Results are presented on the toxic element content of solid waste ashes by INAA and on their uptake of65Zn and109Cd in which there is evidence of two interaction processes between waste particles and simulated groundwater: a rapid exchange (within a few minutes) and slow exchange extending over days. This tends to confirm results on leachability of toxic elements from solid wastes but serves to distinguish adsorption processes from isotopic exchange.
An understanding of radioiodine volatility is important in relation to nuclear reactor safety. In this paper, findings of an ongoing experimental assessment of radioiodine partitioning are described. Radiochemical methods of determining liquid and gas phase speciation are presented along with experimental results demonstrating the validity of these methods. These results also indicate that the majority of the gaseous organic iodides detected at TMI-2 following the accident were in a low molecular weight form such as methyl iodide. It is concluded that, for 10–4 M CsI solutions, the partition coefficient increases by an order of magnitude with increasing pH and, the aqueous and gaseous concentrations of both molecular iodine and organic iodide decrease with increasing pH over the pH range of 4 to 12.
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.
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.
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.
Authors:J. Tsai, S. Owega, G. Evans, R. Jervis, M. Fila, P. Tan and O. Malpica
Summertime urban PM2.5 was collected on cellulose filters in downtown Toronto, using a customized air sampler (635 l/min). Mass concentrations for up to 19 trace elements/ions were measured by ICP-AES, INAA and IC. Source apportionment was performed on these results including additional carbon and total mass concentrations using positive matrix factorization (PMF). PMF factors exhibited trends that indicated soil (18%), stationary (19%), secondary (48%), and vehicle (15%) sources. Potential source contribution function (PSCF) analysis identified probable sources of the stationary and secondary PM2.5 as originating from the south and southwest of Toronto.
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.