Mosquito larvicidal effectiveness of EcoBio-Block S: a novel integrated water-purifying concrete block formulation containing insect growth regulator pyriproxyfen

Stage-specific action of juvenile hormone analogs

The discovery of juvenile hormones (JH) and their synthetic analogs (JHA) generated excitement and hope that these compounds will replace first- and second-generation insecticides that have not so desirable environmental and human safety profiles. However, JHAs used commercially during the past four decades did not meet these expectations. The recent availability of advanced molecular and histological methods and the discovery of key players involved in JH action provided some insights into the functioning of JHA in a stage and species-specific manner. In this review, we will summarize recent findings and stage-specific action of JHA, focusing on three commercially used JHA, methoprene, hydroprene and pyriproxyfen and economically important pests, the red flour beetle, Tribolium castaneum, and the tobacco budworm, Heliothis virescens, and disease vector, the yellow fever mosquito, Aedes aegypti.

Potential synergistic effects of a mixture of mineral trioxide aggregate (MTA) cement and Bacillus subtilis in dental caries treatment

Bacillus subtilis is nonpathogenic in humans and produces a number of useful substances and, therefore, this bacterium is used in probiotic therapy. There have been trials of B. subtilis for patients with periodontitis, but not for patients with caries. Similarly, mineral trioxide aggregate (MTA) cement has been widely used for endodontic treatment, but there are few reports of its use for caries. Therefore, examinations were performed regarding the benefits of addition of B. subtilis to MTA cement for treatment of dental caries. Indirect pulp capping with a mixture of MTA cement and B. subtilis spore powder is effective for avoiding pulpectomy or tooth extraction in such cases (personal communication). This study was planned to examine the scientific basis of this clinical finding, with examination of possible synergistic effects of MTA cement and B. subtilis. From these experiments, the following five results were obtained: (1) B. subtilis did not proliferate in liquid-culture media at pH ≥10. (2) B. subtilis proliferated when mixed with MTA cement. (3) There was no significant difference in proliferation of B. subtilis under aerobic and microaerobic conditions. (4) B. subtilis exhibited antibacterial effects on Staphylococcus aureus and Lactobacillus casei. (5) MTA cement exhibited antibacterial effects on S. aureus and Streptococcus mutans, but not on B. subtilis. These results support the hypothesis that a combination of B subtilis and MTA cement is likely to be clinically useful for treatment of dental caries.

Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam

Background

Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs) form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae.

Methods

We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets), while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti.

Results

The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old children when compared to older children and adults in both control and trial areas.

Conclusions

Our study showed that the treatment by Olyset® Net and pyriproxyfen had a strong negative effect on the prevalence of immature Ae. aegypti, which persisted for at least 5 months after treatment.