Larvicidal activity of endocarp and seed crude extracts of Dracaena loureiri Gagnep against Aedes aegypti (L.) mosquito

Objective: To evaluate the larvicidal activity of the ethanolic and aqueous extracts of the endocarp and seeds of Dracaena loureiri (D. loureiri) against the dengue mosquito vector, Aedes aegypti. Methods: Bioassays were performed by exposing late third-stage to early fourth-stage larvae of Aedes aegypti to various concentrations of the extracts from D. loureiri. The larval mortality was observed after 24- and 48-h exposure. Results: The larvicidal bioassay in this study demonstrated that the ethanolic endocarp extract was the most effective with the LC50 value of 84.00 mg/L after 24 h exposure and < 50 mg/L after 48 h exposure. Extracts from the other parts of the plant were significantly less effective as a larvicide. Conclusions: The ethanolic endocarp extract of D. loureiri demonstrated effective larvicidal activity. It is an alternative source for developing a novel larvicide for controlling this mosquito species

Anopheles (Cellia) rampae n. sp., alias chromosomal form K of the Oriental Maculatus Group (Diptera: Culicidae) in Southeast Asia

Somboon, Pradya, Thongwat, Damrongpan, Harbach, Ralph E. (2011): Anopheles (Cellia) rampae n. sp., alias chromosomal form K of the Oriental Maculatus Group (Diptera: Culicidae) in Southeast Asia. Zootaxa 2810: 47-55, DOI: 10.5281/zenodo.27712

Larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri Gagnep against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquito vectors

Objective: To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquitos. Methods: Larvicidal activity was tested according to World Health Organization standard protocol. The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts (RC-DT 009–014). Larval mortality rates were observed after 24 h and 48 h of exposure. Then, a computerized probit analysis of the mortality data was performed to determine lethal concentration 50 (LC50) and lethal concentration 90 values. Results: Anopheles minimus larvae (24-h LC50 77.88 mg/L) had the highest susceptibility to crude extract, whereas others (Aedes aegypti, 24-h LC50 224.73 mg/L; Aedes albopictus, 24-h LC50 261.75 mg/L; and Culex quinquefasciatus, 24-h LC50 282.86 mg/L) were significantly less susceptible. The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013. The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus, with 24-h LC50 values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013, respectively. Conclusions: The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species. For the most effective alternative larvicide, purification and a phytochemical constituent analysis must be performed

Prevalence and virulence factors of Candida spp. associated with blow flies

Objective: To investigate the prevalence of Candida spp. and the virulence factors of Candida albicans (C. albicans) isolated from external surfaces of blow flies collected from Mae Sot, Tak Province, Thailand. Methods: The blow flies were collected by sterile sweep nets from three areas in Mae Sot. Yeast isolation was first performed on Sabouraud dextrose agar (SDA) supplemented with chloramphenicol and cycloheximide. The yeast isolates were then identified by using chromogenic agar, a yeast identification test kit, a germ tube formation test and a carbohydrate utilization test. The β-hemolysis was determined on 7% sheep blood agar, while phospholipase activity was measured on SDA agar supplemented with 10% egg yolk suspension. Antifungal susceptibility testing was determined by broth micro-dilution testing against ketoconazole and amphotericin B. Results: The prevalence rate of Candida spp. on the external surfaces of the blow flies was 78.1%. All C. albicans isolated from the blow fly demonstrated β-hemolysin and potent phospholipase activities and 47.1% of C. albicans were resistant to ketoconazole with MIC values 128 μg/mL. Conclusions: The results indicate that blow flies could play an essential role in the transmission of potentially pathogenic and antifungal resistant C. albicans into the environment. Further investigation on other virulence factors and genetic relatedness among isolates from the blow flies, the environment and clinical specimens is required to confirm this role

Supplementary data

This file contains sampling localities. Mitochondrial sequence data has been deposited in GenBank with accession numbers HQ403680-HQ404165

Data from: Comparative phylogeography reveals a shared impact of Pleistocene environmental change in shaping genetic diversity within nine Anopheles mosquito species across the Indo-Burma biodiversity hotspot

Southeast Asia is one of the world’s richest regions in terms of biodiversity. An understanding of the distribution of diversity and the factors shaping it is lacking, yet essential for identifying conservation priorities for the region’s highly threatened biodiversity. Here we take a large scale comparative approach, combining data from nine forest associated Anopheles mosquito species and using statistical phylogeographic methods to disentangle the effects of environmental history, species specific ecology, and random coalescent effects. Spatially explicit modelling of Pleistocene demographic history supports a common influence of environmental events in shaping the genetic diversity of all species examined, despite differences in species' mtDNA gene trees. Populations were periodically restricted to allopatric northeastern and northwestern refugia, most likely due to Pleistocene forest fragmentation. Subsequent southwards post-glacial recolonisation is supported by a north-south gradient of decreasing genetic diversity. Repeated allopatric fragmentation and recolonisation has led to the formation of deeply divergent geographical lineages within four species and a suture zone where these intraspecific lineages meet along the Thai-Myanmar border. A common environmental influence for this divergence was further indicated by strong support for simultaneous divergence within the same four species, dating to approximately 900 kya. Differences in the geographical structuring of genetic diversity between species are likely the result of varying species’ biology. The findings have important implications for conservation planning; if the refugial regions and suture zone identified here are shared by other forest taxa, the unique and high levels of genetic diversity they house will make these areas conservation priorities