A variety of formulations of Bacillus thuringiensis var. israelensis de Barjac (B.t.i.) and Bacillus sphaericus Neide (B.s.) have been studied for mosquito control under laboratory and field ...conditions. High efficacy, specificity, low risk of development of resistance, long shelf-life, and transportability, as well as the safety to nontarget organisms of these 2 microbial agents have been well documented. Some of the currently available formulations of B.t.i. and B.s. have low potency per unit mass. Research and development efforts are focusing on commercializing formulations with high potency and low minimum effective dosage that are suitable for long-distance shipment. To achieve this goal, new water-dispersible granule (WDG) formulations of both microbial agents were prepared and made available by Abbott Laboratories for evaluation. The newly developed WDGs of B.t.i. and B.s. with high potency dispersed readily in water with gentle agitation. These WDGs were evaluated and the minimum effective dosages were determined in microcosms against natural populations of Culex mosquitoes. The minimum effective dosage for B.t.i. WDGs with 4,000 International Toxic Units (ITU)/mg was 0.27-0.53 lb/acre which yielded significant control for up to 7-12 days. The minimum effective dosage for B.s. WDGs with 350-630 ITU/mg was 0.05-0.10 lb/acre, which yielded significant control of immature mosquitoes for up to 14-20 days.
Fetal sex pairing and adverse perinatal outcomes in twin gestations Mulla, Zuber D., MSPH, PhD; Plavsic, Sanja Kupesic, MD, PhD; Ortiz, Melchor, PhD ...
Annals of epidemiology,
2013, January 2013, 2013-Jan, 2013-01-00, 20130101, Letnik:
23, Številka:
1
Journal Article
Recenzirano
Abstract Purpose To assess the association between fetal sex pairing in twin pregnancies and adverse perinatal and infant outcomes. Methods A retrospective cohort study of 9770 infants from 4885 twin ...pregnancies delivered in 2007 was conducted with a statewide hospital discharge database for Texas. Log-binomial regression models based on generalized estimating equations were used to calculate relative risks (RR) and 95% confidence intervals (95% CI) for the following dichotomous outcomes: breech presentation, hospital mortality, intrauterine growth restriction (IUGR), low birth weight, prolonged length of stay (>4 days), receipt of mechanical ventilation, and respiratory distress syndrome (RDS). Results The sample was composed of 4918 females and 4852 males. An approximately equal number of infants were from a female–female pregnancy ( n = 3270), mixed-sex pregnancy ( n = 3296), and a male–male pregnancy ( n = 3204). Twins of either sex from mixed-sex pairs were 45% less likely to die in the hospital compared with females from a female–female pregnancy (RR, 0.55, 95% CI, 0.31–0.98). Males from a male–male pair were 33% less likely than females from female–female pairs to experience IUGR (RR, 0.67; 95% CI, 0.53–0.83). The incidence of RDS was significantly increased in males from male–male twin pairs versus females from female–female pairs (RR, 1.21; 95% CI, 1.05–1.41). Conclusions Male infants from male–male twin pairs were more likely to develop RDS and be placed on a ventilator but less likely to experience IUGR than female infants from female–female pairs.
Bacillus sphaericus (Bsph) Neide has been recognized as an effective mosquito larvicide since its discovery 20 years ago. Various strains of this agent, such as 2362, 2297, 1593, and C3-41, have been ...developed, formulated, and field-evaluated against mosquito larvae in different countries. Their high efficacy in controlling mosquitoes breeding in various habitats, especially those in polluted water, has been documented. However, resistance to Bsph has been reported in Culex pipiens complex in both laboratory colonies and natural populations. During our field trials on Bsph water-dispersible granules (WDG) against natural populations of Cx. quinquefasciatus Say in a low-income community, Nonthaburi Province, Thailand, control failure occurred within 4 months after 5 treatments using VectoLex WDG at the dosages of 50-200 mg/m2. The suspected Bsph-resistant Cx. quinquefasciatus mosquitoes were collected and colonized in the laboratory, from which the late stage larvae of generations F14 through F17 were used in bioassays to elucidate the resistance profile. A high level of Bsph resistance was documented in this colony as compared with the susceptible mosquitoes from the same area in Thailand or from California, USA. The resistance ratios (RR) at LC50, depending on reference colonies, were 21,100-28,100-fold against Bsph WDG or greater than 125,000-200,000-fold against Bsph technical-grade material. These Bsph-resistant mosquitoes, however, were completely susceptible to Bacillus thuringiensis var. israelensis, (Bti) preparations, LC50 ranging from 0.017 ppm for technical material with 7000 ITU/mg to 0.052 ppm for water-dispersible granules with 3000 ITU/mg. The RR to mixtures of Bsph + Bti in this highly Bsph-resistant mosquitoes increased steadily upon the increase of Bsph ratios in the mixtures from 50, 75, 90, 95 to 99%. The resistance levels to the mixtures with various ratios of Bsph and Bti, however, were substantially lower than that in Bsph alone, suggesting addition of Bti to Bsph substantially enhanced the mosquitocidal activity (synergism) against these highly Bsph-resistant Cx. quinquefasciatus. Moderate tolerance to low levels of resistance to Bsph/Bti recombinant (RR 7.29-12.75 at LC50 and 5.15-13.40 at LC90) was also noted in this Bsph-resistant population.
We studied the cross-resistance to three highly toxic Bacillus sphaericus strains, IAB-59 (serotype H6), IAB-881 (serotype H3), and IAB-872 (serotype H48), of four colonies of the Culex pipiens ...complex resistant to B. sphaericus 2362 and 1593, both of which are serotype H5a5b strains. Two field-selected highly resistant colonies originating from India (KOCHI, 17,000-fold resistance) and France (SPHAE, 23,000-fold resistance) and a highly resistant laboratory-selected colony from California (GeoR, 36,000-fold resistance) showed strong cross-resistance to strains IAB-881 and IAB-872 but significantly weaker cross-resistance to IAB-59 (3- to 43-fold resistance). In contrast, a laboratory-selected California colony with low-level resistance (JRMM-R, 5-fold resistance) displayed similar levels of resistance (5- to 10-fold) to all of the B. sphaericus strains tested. Thus, among the mosquitocidal strains of B. sphaericus we identified a strain, IAB-59, which was toxic to several Culex colonies that were highly resistant to commercial strains 2362 and 1593. Our analysis also indicated that strain IAB-59 may possess other larvicidal factors. These results could have important implications for the development of resistance management strategies for area-wide mosquito control programs based on the use of B. sphaericus preparations.
Compounds which attract and stimulate oviposition by gravid Culex quinquefasciatus were isolated and identified from a fermented Bermuda grass infusion. The neutral portion of the ether extract of ...the aqueous infusion contained the stimulatory materials. Fractionation by liquid chromatography yielded an active fraction containing phenol, 4-methylphenol, 4-ethylphenol, indole and 3-methylindole. A blend of the 5 compounds strongly stimulated oviposition, as did blends of any 4 of them. Bioassays with individual compounds showed that only 3-methylindole consistently induced oviposition, in concentrations spanning 5 orders of magnitude.
To gauge the extent of mosquito problems and their impact on local people in Thailand, a simple questionnaire was designed consisting of 6 questions with multiple choices to be answered in 4 ...different communities in Thailand in 1998 and 1999. Mosquito biting activity was noted often by respondents. They reported that mosquitoes bit both night and day, and that the insects were abundant both in the dry and the rainy seasons. In all 4 communities, a large proportion of the residents used bed nets, mosquito coils, and aerosol sprays for personal protection; vaporizing mats and repellents were used sparingly. The cost of such measures amounted to dollars 4 to dollars 25 per year per household. For most of the residents, this represented a substantial proportion of their income, and was proportionally greater than the average cost of organized mosquito control in developed countries. This suggests that instituting organized local vector control programs would be cheaper and more effective than the individual use of personal protectants that do not reduce mosquito numbers. An assessment of the available products stocked in neighborhood stores and supermarkets for personal protection was made. A variety of insecticidal aerosols, mosquito coils, liquid sprays, vaporizing mats, and vaporizing liquids was stocked. This ample supply of household insecticides lends support to the preferred methods of protection reported by the respondents. The active ingredients in most of the formulations were synthetic pyrethroids, although a few contained dichlorvos, propoxur, and a few other compounds. Mosquito coils, the most preferred products used by the poor, were evaluated for efficacy, and were found to provide a reduction of 72-96% in landing-biting rates in controlled experiments.
Insulin resistance, characterized by an inexorable decline in skeletal muscle glucose utilization and/or an excessive hepatic glucose production, constitutes a major pathogenic importance in a ...cluster of clinical disorders including diabetes mellitus, hypertension, dyslipidemia, central obesity and coronary artery disease. A novel concept suggests that heightened state of oxidative stress during diabetes contributes, at least in part, to the development of insulin resistance. Several key predictions of this premise were subjected to experimental testing using Goto–Kakizaki (GK) rats as a genetic animal model for non-obese type II diabetes. Euglycemic–hyperinsulinemic clamp studies with an insulin infusion index of 5 mU/kg bw/min were used to measure endogenous glucose production (EGP), glucose infusion rate (GIR), glucose disposal rate (GDR) and skeletal muscle glucose utilization index (GUI). Moreover, the status of oxidative stress as reflected by the urinary levels of isoprostane and protein carbonyl formation were also assessed as a function of diabetes. Post-absorptive basal EGP and circulating levels of insulin, glucose and free fatty acid (FFA) were elevated in GK rats, compared to their corresponding control values. In contrast, steady state GIR and GDR of the hyperglycemic/hyperinsulinemic animals were reduced, concomitantly with impaired insulin's ability to suppress EGP. Insulin stimulated
3H-2-deoxyglucose (2-DG) uptake (a measure of glucose transport activity) by various types of skeletal muscle fibers both in vivo and in vitro (isolated muscle, cultured myoblasts) was diminished in diabetic GK rats. This diabetes-related suppression of skeletal muscle glucose utilization was associated with a decrease in insulin's ability to promote the phosphorylation of tyrosine residues of insulin receptor substrate-1 (IRS-1). Similarly, the translocation of GLUT-4 from intracellular compartment to plasma membrane in response to insulin was also reduced in these animals. Oxidative stress-based markers (e.g. urinary isoprostane, carbonyl-bound proteins) were elevated as a function of diabetes. Nullification of the heightened state of oxidative stress in the GK rats with α-lipoic acid resulted in a partial amelioration of the diabetes-related impairment of the in vivo and in vitro insulin actions.
Collectively, the above data suggest that 1) insulin resistance in GK rats occurs at the hepatic and skeletal muscle levels, 2) muscle cell glucose transport exhibited a blunted response to insulin and it is associated with a major defect in key molecules of both GLUT-4 trafficking and insulin signaling pathways, 3) skeletal muscle insulin resistance in GK rats appears to be of genetic origin and not merely related to a paracrine or autocrine effect, since this phenomenon is also observed in cultured myoblasts over several passages and finally heightened state of oxidative stress may mediate the development of insulin resistance during diabetes.
Gerry Killeen and colleagues argue that malaria eradication efforts will not be successful until a better understanding of the ecology and evolution of the mosquito vectors is gained.
Neem (Azadirachta indica A. Juss) products have been shown to exert pesticidal properties against a variety of insect species. In mosquito control programs, such products may have the potential to be ...used successfully as larvicides. In exploring other advantages of neem products, we studied the oviposition responses of Culex tarsalis Coquillett and Cx. quinquefasciatus Say to two experimental azadirachtin (AZ) formulations, wettable powder Azad™ WP10 (WP) and emulsifiable concentrate Azad™ EC4.5 (EC). Gravid Cx. tarsalis exhibited a distinct preference for the neem suspension of the WP, where significantly more egg rafts were collected from the treatment than from the control. The minimum effective AZ concentration for this activity was 0.5 ppm. The aged suspensions from 1–7 days at 0.5 and 1 ppm AZ were more active in eliciting oviposition responses in Cx. tarsalis than the fresh preparations. This activity of the aged suspensions lasted up to 14 and 21 days at 0.5 and 1 ppm AZ, respectively. Negative ovipositional responses were indicated in the tests of the EC vs. Cx. tarsalis, as well as both neem formulations vs. Cx. quinquefasciatus. In the tests of the EC formulation, significantly less gravid females were trapped by oviposition cups in the treatment than in the control, and in the tests of the WP significantly less egg rafts were collected from the treatment than from the control. The minimum effective concentrations for oviposition avoidance activity were 5 ppm AZ for Cx. tarsalis and 10 ppm AZ for Cx. quinquefasciatus, which lasted up to 1 and 4 days for these two species respectively. Neem products potentially used as mosquito larvicides may have many additional benefits in mosquito control programs, the oviposition modification noted in the current studies is one such example.
Aedes aegypti (L.) is known as vector of dengue and chikungunya fever. Larvicides are used to control this vector. We evaluated the efficacy of newly developed formulations of larvicides to control ...Ae. aegypti under field conditions for 24 weeks post single application. Mosdop P and Mosdop TB containing diflubenzuron (2% and 40 mg/tablet, respectively) as the active ingredient, were applied at a dosage of 0.1 mg a.i./1 and Mosquit TB10, Mosquit TB100 and Temecal containing temephos (1%, 10% and 1%, respectively) as the active ingredient were applied at a dosage of 1 mg active ingredent (a.i.) to 200 liter water storage jars. Two water regimens were used in the jars: in one regimen the jar was kept full of water all the time and in the other regimen a full jar had half the volume removed and refilled weekly. The larvicidal efficacy was reported as the level of inhibition of emergence (IE%) calculated based on the pupal skins in the jars versus the original number of larvae added. Mosdop P, Mosdop TB, Mosquit TB10, Mosquit TB100 and Temecal showed complete larvicidal efficacy (100% IE) in the constantly full jars for 16, 17, 14, 20 and 13 weeks posttreatment, respectively; in the jars where half the volum of water was replaced weekly, the larvicides had complete larvicidal efficacy (100% IE) for 19, 20, 17, 24 and 15 weeks post-treatment, respectively. The five larvicide regimens evaluated in this study are effective for controlling Ae. aegypti larvae.
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