Impact of larviciding with a Bacillus thuringiensis israelensis formulation, VectoBac WG, on dengue mosquito vectors in a dengue endemic site in Selangor State, Malaysia.

The field bioefficacy of a wettable granule (WG) formulation of Bacillus thuringiensis israelensis (Bti), VectoBac WG (Bti strain AM65-52) against dengue vectors, Aedes aegypti and Ae albopictus; was evaluated in a suburban residential area (TST) and in a temporary settlement site (KB) in the state of Selangor, Malaysia. Pre-control ovitrap surveillance of the trial sites indicated a high population of both types of Aedes mosquitoes. The populations were monitored continuously by weekly ovitrapping. Bti was sprayed biweekly at a dosage of 500 g/ha by using a mist-blower. The spray application was targeted into outdoor larval habitats. If required, Bti formulation was also applied directly into indoor water-holding containers at 8 g/1,000 l. Based on ovitrap surveillance, a significant reduction in Aedes populations was evident 4 weeks after initiating the first Bti treatment. The ovitrap index (OI) and the larvae density decreased drastically in both trial sites. In TST, the indoor OI was significantly reduced from 57.50 +/- 7.50% to 19.13 +/- 5.49% (p<0.05), while the outdoor OI decreased from 38.89 +/- 11.11% to 15.36 +/- 5.93%. In KB, similarly, the OI was significantly reduced by more than half, from 66.66 +/- 6.67% to 30.26 +/- 2.99% (p< 0.05). In all cases, the reduction in OI was paralleled by reduction in larval density.

Field evaluation of the bioefficacy of diflubenzuron (Dimilin) against container-breeding Aedes sp. mosquitoes.

The inhibitory activity of diflubenzuron, a chitin synthesis inhibitor, on the ecdysis of Aedes sp. larvae was evaluated in earthen jars and automobile tires. Two formulations of diflubenzuron were used in this study: Dimilin(R) WP (wettable powder), 25% and Dimilin GR (granular), 2%. The equivalent rate of 25 g/ha, 50 g/ha and 100 g/ha active ingredients for both WP and GR formulations were used in this study. Generally, at the higher dosage of 100 g/ha, both formulations were more effective against Aedes mosquitoes. On the whole, the WP formulation appeared to perform better than the GR formulation in terms of residual activity.

Inversion of ferromagnetic proximity polarization by MgO interlayers.

We investigate the spin-dependent reflection properties in Fe/MgO/GaAs heterostructures by optical pump-probe measurement of the ferromagnetic proximity polarization (FPP). As a function of MgO thickness, the FPP is initially enhanced (<2.0 A) and then exhibits an unexpected sign reversal at approximately 5.0 A. The identification of two competing thresholds in the intensity dependence of FPP and the observation of FPP sign reversal in Fe/Mg/GaAs suggest that the inversion of FPP is related to an interfacial bonding effect.

The value of serial cerebrospinal fluid 14-3-3 protein levels in adult community-acquired bacterial meningitis.

BACKGROUND: Increased levels of cerebrospinal fluid (CSF) 14-3-3 proteins have been reported in acute bacterial meningitis. We tested the hypothesis that CSF 14-3-3 protein levels are substantially increased in acute bacterial meningitis and decreased after anti-microbial therapy, and that CSF 14-3-3 protein levels can predict treatment outcomes. METHODS: We examined serial pan-CSF 14-3-3 (14-3-3-P) protein and five major isoform (beta, gamma, epsilon, eta, zeta) levels in 29 adult community-acquired bacterial meningitis (ACABM) patients. The CSF 14-3-3 protein levels were also evaluated in 12 aseptic meningitis patients during the study period. RESULTS: All of the meningitis patients had a positive result on admission. Levels of CSF 14-3-3 protein in ACABM cases were significantly increased initially, and substantially decreased thereafter. Most of those who survived (survivors = 25 and non-survivors = 4) had nearly cleared their 14-3-3 protein from the CSF before discharge. Conversely, patients who died never cleared their CSF 14-3-3 protein. The median value of CSF 14-3-3-P and 14-3-3 gamma, 14-3-3 eta and 14-3-3 epsilon isoforms on admission in the bacterial meningitis group were 173.7, 137.7, 42.2 and 9.1, respectively, which were statistically significant than those of the aseptic meningitis group (48.4, 39.6, 2.5 and 0, respectively). Stepwise logistic regression analysis showed only CSF 14-3-3 gamma isoform on admission was independently associated with outcome (P = 0.05, OR = 0.991). CONCLUSION: Serial 14-3-3 protein gamma isoform actually meets the major requirements for outcome prediction in the treatment of ACABM patients. Assay of the 14-3-3 protein gamma isoform should be added as a neuro-pathologic marker among the panel of conventional CSF parameters.

Light-enhanced electro-optic spectral tuning in annealed proton-exchanged periodically poled lithium niobate channel waveguides.

We report the observation of light-enhanced electro-optic spectral tuning in annealed proton-exchanged, asymmetric domain-duty-cycle periodically poled lithium niobate (PPLN) channel waveguides for second-harmonic generation. The spectral tuning rate was increased rapidly from 0.07 nm/(kV/mm) to a saturated value of 0.32 nm/(kV/mm) in a 30%/70% domain-duty-cycle PPLN waveguide when the fundamental pump power near 1534 nm was increased from 0.6 to 46 mW. The second-harmonic laser power at 767 nm was identified to be the source enhancing the spectral tuning.

Mixed breeding of Aedes aegypti (L.) and Aedes albopictus Skuse in four dengue endemic areas in Kuala Lumpur and Selangor, Malaysia.

Ovitrap surveillance was conducted in four dengue endemic areas in Kuala Lumpur and Selangor, Malaysia to determine the distribution and percentage of mixed breeding of both Aedes aegypti and Aedes albopictus. The percentage of mixed breeding in all study sites both indoors and outdoors accounted for 10 to 32 % from the total ovitraps collected. Ae. aegypti was found at a higher frequency than Ae. albopictus in these ovitraps. This study again indicates that ovitrap is a sensitive tool to attract gravid females of more than one mosquito species to oviposit in the container.

Compatibility of Bacillus thuringiensis serovar israelensis and chemical insecticides for the control of Aedes mosquitoes.

The compatibility of the commercial aqueous Bacillus thuringiensis serovar israelensis (B.t.i.) formulation, Vectobac 12AS, with the chemical insecticides Actellic 50EC, Aqua Resigen, Resigen, and Fendona SC, for the simultaneous control of Aedes larvae and adults was studied by dispersing nine different formulations using a portable mist blower, in single story half-brick houses. The effectiveness of the treatment was evaluated by measuring the larval mortality, adult mortality, and droplet analysis at varying distances from the sprayer. Persistence of the larvicidal activity of the chemical insecticides and B.t.i was also determined by measuring the larval mortality in the test samples 7 days posttreatment. The sprayed particles in all the trials were 50-60 microns in size, indicating that the particles were those of mist spray. Test samples placed within 3 m from the sprayer gave the maximum larval and adult mortality. Chemical insecticides exhibited maximum larval mortality in the 1 h posttreatment test samples and it was comparable to the larvicidal activity of B.t.i. The larvicidal toxins of B.t.i were more stable and were able to affect sufficient larval mortality for 7 days posttreatment. The larvicidal activity of the mixtures, i.e., chemical insecticides with B.t.i, in the 1 h posttreatment test samples was not significantly different from the larvicidal activity of the chemical insecticides and it was comparable to the larvicidal activity of B.t.i alone. However, the larvicidal activity of the mixtures was significantly more than the chemical insecticides alone in the 7 days posttreatment test samples except for the Actellic 50EC and Vectobac 12AS mixture. In all the trials, with or without B.t.i, there was no significant difference in adult mortality, indicating that this B.t.i formulation, Vectobac 12AS, was not antagonistic to the adulticidal activity of the chemical insecticides. From this study, it can be concluded that chemical insecticides can be used effectively for both adult and larval control, but the chemical insecticides do not exhibit residual larvicidal activity. Hence, for an effective control of both Aedes larvae and adults, it is advisable to add B.t.i. to the chemical insecticides, as B.t.i is specifically larvicidal and is also able to effect extended residual larvicidal activity.

Preliminary field evaluation of the combined adulticidal, larvicidal, and wall residual activity of ULV-applied bifenthrin against mosquitoes.

The combined adulticidal, larvicidal, and wall residual activity of ULV-applied bifenthrin, a synthetic pyrethroid, was evaluated in houses in Kuala Lumpur, Malaysia, against larvae and adults of lab-bred Aedes aegypti and Culex quinquefasciatus. A portable ULV sprayer was used to disperse a ULV formulation of bifenthrin at a discharge rate of 45 ml/min. The results indicated that bifenthrin sprayed at this rate exhibited all the three activities against the test mosquitoes. Complete adult mortalities were achieved, while very high larvicidal activity was also effected, which persisted for seven days. Wall bioassay with adults of Ae aegypti also resulted in very high mortality, which also persisted for one week. The combined mosquitocidal activities of bifenthrin is considered more effective especially in the control of dengue vectors.