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The emergence of West Nile virus (WNV) in the Western Hemisphere in 1999 poses an ongoing public health threat in North America as the most common cause of epidemic encephalitis [...]

West Nile virus (WNV) is a mosquito-borne flavivirus belonging to the Japanese encephalitis serogroup and maintained in an enzootic cycle between mosquitoes (primarily Culex spp.) and birds. Mammals such as [...]

The accumulation and fixation of mutations in West Nile virus (WNV) led to the emergence of a dominant genotype throughout North America. Subsequent analysis of 44 isolates, including 19 new [...]

A description is provided of the synthesis and characterization of a series of compounds involving the bis(di(o-N,N-dimethylanilinyl)phosphino)-methane(dmapm) ligand. The potential of dmapm to function as a bridging ligand that is capable of enhancing metal-metal cooperativity in heretobinuclear complexes of group 8 and group 9 metals and the roles of the coordinated amines as labile groups for the generation of coordinative unsaturated species remain to be demonstrated.

Reaction of [Fe[(CO).sub.4]([[eta].sup.2]-BTMSA)] (1) (BTMSA = [Me.sub.3]SiCCSi[Me.sub.3]) with trimethylphosphine proceeds by stepwise loss of CO ligands yielding [Fe[(CO).sub.3](P[Me.sub.3]) ([[eta].sup.2]-BTMSA)] (2) and [Fe[(CO).sub.2][(P[Me.sub.3]).sub.2]([[eta].sup.2]-BTMSA)] (3), respectively. This demonstrates the CO dissociative nature of substitution in 1 toward P[Me.sub.3], as established in analogous M[(CO).sub.4] ([[eta].sup.2]-alkyne) (M = Fe, Ru, Os) compounds. The structures of all three compounds have been determined by X-ray crystallography to assess the effect of CO substitution by P[Me.sub.3] on the metal-alkyne bonding in these molecules. Key words: iron, carbonyl, alkyne, substitution, phosphine, steric effects. La reaction du [Fe[(CO).sub.4]([[eta].sup.2]-BTMSA)] (1) (BTMSA = [Me.sub.3]SiCCSi[Me.sub.3]) avec la trimethylphosphine se produit avec des pertes successives de ligands CO qui conduisent respectivement aux complexes [Fe[(CO).sub.3](P[Me.sub.3])([[eta].sup.2]-BTMSA)] (2) et [Fe[(CO).sub.2][(P[Me.sub.3]).sub.2]([[eta].sup.2]-BTMSA)] (3). Ces resultats confirment la nature dissociative du CO qui permet de le substituer dans le compose 1 par des groupes P[Me.sub.3], tel qu'il avait ete etabli avec les analogues M[(CO).sub.4]([[eta].sup.2]-alcyne) (M = Fe, Ru, Os). Les structures des trois composes ont ete determinees par cristallographie aux rayons X afin d'evaluer l'effet de la substitution du CO par un P[Me.sub.3] sur la liaison metal-alcyne de ces molecules. Mots cles : fer, carbonyle, alcyne, substitution, phosphine, effets steriques. [Traduit par la Redaction]

The Rh/Os complex, has a unique ability to couple diazomethane- generated methylene groups to yield C-3 and C-4 containing products. This clearly demonstrates the importance of bridging binding modes of hydrocarbyl fragments in methylene-coupling sequences.

The comparative efficacy of ultra-low volume applications of deltamethrin, permethrin, and malathion against specific adult populations of Culex quinquefasciatus, a primary regional vector of Saint Louis encephalitis and West Nile virus, using field cage tests is described. At labeled application rates, the estimated mass median diameters for Fyfanon®, Evoluer™, and DeltaGard® were 18.32, 19.24, and 17.44 μm, respectively. No significant differences ( P ≥ 0.01) in mean percent control were observed across all 3 wild populations and a susceptible Sebring strain tested with Fyfanon, DeltaGard, and Evoluer, providing 98.25%, 98.20%, and 97.24% mean percent control. Mean percent control for Sebring and 3 wild populations was 99.38%, 97.79%, 97.26%, and 97.15%, respectively, which were not significantly different from one another ( P ≥ 0.01). Across all tests, highly significant differences ( P ≤ 0.01) in mean percent control were obtained at 30.48, 60.96, and 91.44 m distances downwind, with mean percent control at 91.44 m being significantly less than that observed at 30.48 m, but not at 60.96 m. Individually, tests for DeltaGard, Fyfanon, and Evoluer resulted in no significant differences ( P ≥ 0.01) in mean percent control between all mosquito populations tested, ranging from 96.47 to 100. However, Evoluer obtained significantly less ( P ≤ 0.01) mean percent control at 91.44 m compared to DeltaGard and Fyfanon. Data suggest that the wild Cx. quinquefasciatus specimens collected were as susceptible as the laboratory Sebring strain. The use of Sebring as positive controls downwind strongly supported determination of the efficacy of all adulticides and susceptibility of wild populations tested. [ABSTRACT FROM AUTHOR]

The Larvasonic™ Field Arm Mobile Wetlands Unit and SD-Mini were tested for efficacy against Culex larvae, and effects on aquatic nontarget organisms (NTO). The Field Arm provided 84.61% to 100% control of caged Culex larvae out to 0.91-m distance in shallow ditches and 60.45% control of Culex larvae at 0.61-m without any effects to caged NTO. Slow ditch treatment achieved 77.35% control compared to fast treatment (20.42%), whereas 77.65% control was obtained along edges of a neglected swimming pool, compared to near the middle (23.97%). In bucket tests, the SD-Mini provided >97% control of Culex and 85.35% reduction of immature giant water bugs, which decreased slightly (83.45%) over the monitoring period, which was not significantly different from cannibalistic damselflies (62.80%), with reduction of both being significantly higher than other NTO tested. There was a small (0.37%) reduction of dragonflies (naiads), due to cannibalism. Both Larvasonic units could effectively augment conventional larvicide operations in smaller areas without causing resistance within mosquito populations or harming NTO when used properly. [ABSTRACT FROM AUTHOR]

Reaction of [Fe(CO)4(η2-BTMSA)] (1) (BTMSA = Me3SiCCSiMe3) with trimethylphosphine proceeds by stepwise loss of CO ligands yielding [Fe(CO)3(PMe3)(η2-BTMSA)] (2) and [Fe(CO)2(PMe3)2(η2-BTMSA)] (3), respectively. This demonstrates the CO dissociative nature of substitution in 1 toward PMe3, as established in analogous M(CO)4(η2-alkyne) (M = Fe, Ru, Os) compounds. The structures of all three compounds have been determined by X-ray crystallography to assess the effect of CO substitution by PMe3 on the metal–alkyne bonding in these molecules. [ABSTRACT FROM AUTHOR]

The mixed-metal complex, [RhOs(CO)4(dppm)2][BF4] (1; dppm = µ-Ph2PCH2PPh2) reacts with diazomethane to yield a number of products resulting from methylene incorporation into the bimetallic core. At -80 °C the reaction between 1 and CH2N2 yields the methylene-bridged [RhOs(CO)3(µ-CO2)(µ-CO)-(dppm)2][BF4] (2), which reacts further at ambient temperature to give the allyl methyl species, [RhOs(η¹-C3H5)(CH3)(CO)3(dppm)2][BF4] (4). At intermediate temperatures compounds 1 and 2 react with diazomethane to yield the butanediyl complex [RhOs(C4H8)(CO)3(dppm)2][BF4] (3) by the incorporation and coupling of four methylene units. compound 2 is proposed to be an intermediate in the formation of 3 and 4 from 1 and on the basis of labeling studies a mechanism has been proposed in which sequential insertions of insertions of diazomethane-generated methylene fragments into the Rh-C bond of bridging hydrocarbyl fragments occur. Reaction of the tricarbonyl species, [Rhos(CO)3(µ-CH2)(dppm)2][BF4] with diazomethane over a range of temperatures generates the ethylene complex [RhOs(η²-C2H4)(CO)3(dppm)2][BF4] (7a), but no further incorporation of methylene groups is observed. [ABSTRACT FROM AUTHOR]

Among 7 traps tested, significantly higher (P < 0.01) mean numbers of Aedes albopictus (269) and Aedes aegypti (55) females were collected within the Mosquito Magnet Liberty trap compared with the remaining traps. The second highest mean captures for both species were obtained from omnidirectional Fay-Prince (77 Ae. albopictus) and Dragonfly (13 Ae. aegypti) traps, which were not significantly different (P > 0.01) from an experimental moving-target trap that produced mean captures of 40 Ae. albopictus and 6 Ae. aegypti (alpha = 0.01). In terms of Ae. albopictus capture, no significant differences (P > 0.01) existed between Dragonfly, CDC without light (CDC -), and CDC with light (CDC +) captures, which were significantly different (P < 0.01) from Mosquito Deleto. No statistical significance existed between moving-target, omnidirectional, CDC +, CDC -, and Mosquito Deleto traps in terms of Ae. aegypti capture (P > 0.01), individual trap positions, or number of Ae. albopictus and Ae. aegypti females collected throughout the 21-day test (P > 0.05). Mosquito Magnet Liberty collected 7,208 Ae. albopictus, 1467 Ae. aegypti, and 13 other species representing 5 genera, which comprised the largest total (9662) and percentage (62.5%) of mosquitoes collected by all traps combined. Omnidirectional and moving-target traps captured 1941 and 1050 Ae. albopictus, 138 and 220 Ae. aegypti, and 2171 (14.0%) and 1397 (9.0%) of the total mosquitoes captured by all traps, with 8 and 10 species representing 5 genera, respectively, included in these collections. The Dragonfly captured 476 Ae. albopictus, 376 Ae. aegypti, and 1008 total specimens (6.5%) representing 8 species and 4 genera in these collections. CDC + and CDC - traps collected nearly identical numbers of Ae. albopictus (431, 450) and Ae. aegypti (71, 71) with 537 (3.4%) and 551 (3.5%) total specimens, respectively. Eight species representing 5 genera were captured from CDC +, whereas CDC - captured 6 species representing 4 genera. Mosquito Deleto captured 118 mosquitoes, including 19 Ae. albopictus and 62 Ae. aegypti females (0.7%), with 6 species representing 4 genera. Battery-powered traps with contrasting color schemes and movement worked considerably better than stationary CDC miniatures without color or movement. Omnidirectional Fay-Prince and moving-target traps without octenol captured Ae. albopictus and Ae. aegypti females as frequently as some commercial traps. Additionally, costs incurred per mosquito trapped, future trap design, and important consumer-centered issues are briefly discussed.

The effects of fipronil and lambda-cyhalothrin, applied at rates labeled for control of the rice water weevil, Lissorhoptrus oryzophilus, on 3 nontarget indigenous insect species in Arkansas rice are described. Three replicates of untreated control checks and fipronil- and lambda-cyhalothrin-treated plots containing 3 sentinel cages each were performed. Ten 4th-stage larvae of Anopheles quadrimaculatus, 10 adult Tropisternus lateralis, or 10 adult Notonecta indica were placed within individual cages in small rice plots treated with ICON 6.2 FS (fipronil) at 0.025 lb active ingredient (AI)/acre (0.028 kg/ha) or KARATEZ 2.08 CS (lambda-cyhalothrin) at 0.03 lb AI/acre (0.033 kg/ha) applied over vegetation and water with a single-boom sprayer. At 24 h after treatment in fipronil plots, significantly higher control of An. quadrimaculatus and T. lateralis (69 and 48% control, respectively) was achieved, compared to N. indica (18%). In lambda-cyhalothrin plots 24 h after treatment, 100% reductions of both T. lateralis and N. indica were highly significant (P < 0.05) from the lower level of control in An. quadrimaculatus (10%). At 48 h after treatment, no significant, differences existed between all species within fipronil plots, with An. quadrimaculatus, T. lateralis, and N. indica obtaining 41, 10, and 7% control, respectively. Significantly higher (P < 0.05) control was obtained in lambda-cyhalothrin plots 48 h after treatment, with 93 and 53% control of T. lateralis and N. indica, respectively, compared to 7% control of An. quadrimaculatus. A marked difference in susceptibility was found between selected nontarget organisms used in this study. When using lambda-cyhalothrin to control adult L. oryzophilus, populations of nontarget beneficial insects, such as T. lateralis and N. indica, could be adversely affected, whereas nontarget pestilent species, such as An. quadrimaculatus, could proliferate. Fipronil achieved higher percentages of control against An. quadrimaculatus, compared to lambda-cyhalothrin, and was less harmful to both nontarget predators.