An evaluation of Bacillus thuringiensis israelensis (AM65-52) treatment for the control of Aedes aegypti using vehicle-mounted WALS® application in a densely populated urban area of Puerto Rico.

BACKGROUND: With a shortage of effective options for control of Aedes aegypti in Puerto Rico due to widespread resistance to conventional mosquito adulticides, an alternative approach was investigated to reduce vector populations. In two areas (totaling 144 ha) of the municipality of Bayamón, Puerto Rico, Bacillus thuringiensis israelensis (Bti) AM65-52 WDG was applied at a rate of 500 g/ha using vehicle-mounted aqueous wide-area larvicide spray applications weekly for 4 weeks and then every other week for a further 16 weeks. Bioassay jars were placed in the field to monitor for deposition of Bti droplets in open spaces, and under vegetation and building coverage. Autocidal gravid ovitraps were placed throughout the field site to monitor the population of adult female Ae. aegypti in both treatment and control sites. RESULTS: Larvicide spray was successfully deposited into jars in an array of open and covered locations, as confirmed by larval bioassays. After the fourth weekly spraying, differences in autocidal gravid ovitrap densities were observed between treatment and control sites resulting in 62% (P = 0.0001) and 28% (P < 0.0001) reductions in adult female Ae. aegypti numbers. CONCLUSION: Repeated wide-area larvicide spray application of Bti AM65-52 WDG to residential areas in Puerto Rico effectively suppressed dengue vector populations. The success of this trial has led to expansion of the WALS® program to a larger area of Bayamón and other municipalities in Puerto Rico. © 2020 Society of Chemical Industry.

Understanding Information Seeking about the Health of Others: Applying the Comprehensive Model of Information Seeking to Proxy Online Health Information Seeking.

A significant proportion of online health information seeking is related to the health of others, such as the one of family members and friends, instead of an individual's own health. Understanding these behaviors of proxy seekers, i.e., individuals who seek information about the health of others, can improve the transmission of health information to and social support for others. The comprehensive model of information seeking (CMIS) is an established model that predicts information seeking for the individual seeker. The model was modified and extended with concepts of social network ties to predict proxy information seeking intentions and the resulting social support intentions. Hypothetical scenarios of persons from the social network suffering from depression were varied in severity of disease and the relationship closeness to test their influence on model variables. Structural equation modeling (N = 607) served to evaluate the associations between the health-related factors and proxy health information seeking intentions, as well as support intentions. The results confirmed the direct effects of beliefs on information-carrier utility. Contrary to expectations, demographics, experience, and salience had direct effects on proxy information seeking intentions. The results indicate that a modified CMIS helps to better meet surrogate seekers' needs for supporting patients.

Field efficacy of granular formulations of Bacillus thuringiensis Israelensis--strain AM65-52 against floodwater mosquitoes in Poland and Germany.

This paper presents results of studies evaluating the efficacy of various granular formulations of VectoBac (Bacillus thuringiensis israelensis de Barjac [Bti] H-14 strain AM65-52) against immature mosquitoes in 2 distinct habitats in Poland and Germany. Meadows intermittently flooded with sewage water in the city of Wroclaw, Poland, provide ideal habitats for immature stages of Aedes caspius, Ae. vexans, and Culex pipiens pipiens. Helicopter applications of VectoBac G and VectoBac TP sand granules (VectoBac TP-SG) at rates of 5 and 10 kg/ha to the meadows resulted in between 70.9% and 97.4% larval mortality. In Germany, some swampy woodlands in the upper Rhine Valley provide ideal habitats for snowmelt mosquitoes, Aedes cantans, Ae. punctor, Ae. rusticus, and Ae. communis. Ground applications of VectoBac G, VectoBac TP-SG, and VectoBac WG IcyPearls (VectoBac WG-IP) were made to these habitats when the water temperature was approximately 7 degrees C. Larval mortality at 7-day post-application ranged from 90.9% (VectoBac TP-SG: 10 kg/ha) to 98.0% (VectoBac WG-IP: 15 kg/ha). In a separate microcosm trial within the same habitat, all 3 granule formulations controlled larvae of Ae. cantans for 3 wk.

Evaluation of three microbial formulations against Culex pipiens pipiens larvae in irrigation fields in Wroclaw, Poland.

Two evaluations of microbial mosquito larvicides were conducted in irrigation fields located along the Odra River near the city of Wroclaw, Poland. In the first evaluation, 3 dosages each of Bacillus thuringiensis israelensis (Bti)--VectoBac water dispersible granule (WDG) and VectoBac aqueous suspension formulation (12AS)--and Bacillus sphaericus (Bs)--VectoLex WDG--were tested against larvae of Culex pipiens pipiens. There was little difference between formulations and rates of application between day 2 and 7 following the treatment. VectoBac WDG at 300 g/ha resulted in 100% mortality of Cx. p. pipiens. Between 0.5 and 1 liter of VectoBac 12AS caused sufficient mortality for up to 7 days. The effective shortterm application rate of VectoLex WDG was found to be 400 g/ha. The above doses can be recommended for up to 7-day control in this habitat. In the second evaluation, using VectoBac WDG at 800 g/ha, the residual efficacies of 2 ground application methods, a knapsack sprayer configured for large droplet application and a motorized backpack blower configured for small droplet application, were compared. The results indicated no significant difference between the 2 application methods, but a significant long-term effect of VectoBac WDG was observed at the rate of 800 g/ha.

Field trials with tank mixtures of Bacillus thuringiensis subsp. israelensis and Bacillus sphaericus formulations against Culex pipiens larvae in septic tanks in Antalya, Turkey.

Efficacy of tank mixtures of commercial Bacillus thuringiensis subsp. israelensis (Bti) and Bacillus sphaericus (Bs) water-dispersable granule (WDG) formulations was evaluated in septic tanks, against Culex pipiens L. (Diptera: Culicidae) larvae. VectoLex WDG (Bs) + VectoBac WDG (Bti) were evaluated at various ratios from 488 g/ha VectoLex + 250 g/ha VectoBac up to 3,000 g/ha of each. All applications and ratios delivering VectoLex WDG at a rate equal to or greater than 988 g/ha provided more than 90% control for 28 days after treatment. The lowest dose provided this level of control for at least 7 days after treatment, with greater than 80% control after 2 wk. These results suggest that a retreatment interval of 2 wk is recommended with the lowest dose and retreatment intervals of 4 or more wk are recommended with the doses equal to or higher than 988 g/ha VectoLex + 250 g/ha VectoBac.

Influence of temperature and concentration of VectoBac on control of the salt-marsh mosquito, Ochlerotatus squamiger, in Monterey County, California.

Laboratory susceptibility bioassays were conducted to determine the efficacy of VectoBac TP (Bacillus thuringiensis var. israelensis [Bti]) at different concentrations and temperatures against the salt-marsh mosquito Ochlerotatus squamiger. Bioassays on late 3rd- and early 4th-stage larvae, read at 72 h and 14 degrees C produced an LD90 of 0.223 mg/liter, whereas more than double this dose was required to produce similar mortality at 6 degrees C. A field trial in the winter of 2001-02 of an aerially applied VectoBac TP formulation in Salinas, CA, corroborated laboratory bioassay observations by producing 97-100% control of Oc. squamiger at 72 h postapplication. Inconsistencies in mortality with field applications of VectoBac TP previously observed by North Salinas Valley Mosquito Abatement personnel were most likely caused by uneven application rates and varying temperatures and water volumes.