Comparison of BG-Sentinel® Trap and Oviposition Cups for Aedes aegypti and Aedes albopictus Surveillance in Jacksonville, Florida, USA.

The BG-Sentinel® (BGS) trap and oviposition cups (OCs) have both proven effective in the surveillance of Aedes species. This study aimed to determine which of the 2 traps could best characterize the relative population sizes of Aedes albopictus and Aedes aegypti in an urban section of Jacksonville, FL. Until 1986, Ae. aegypti was considered the dominant container-breeding species in urban northeastern Florida. Since the introduction of Ae. albopictus, Ae. aegypti has become almost completely extirpated. In 2011, a resurgence of Ae. aegypti was detected in the urban areas of Jacksonville; thus this study initially set out to determine the extent of Ae. aegypti reintroduction to the area. We determined that the BGS captured a greater number of adult Ae. aegypti than Ae. albopictus, while OCs did not monitor significantly different numbers of either species, even in areas where the BGS traps suggested a predominance of one species over the other. Both traps were effective at detecting Aedes spp.; however, the BGS proved more diverse by detecting over 20 other species as well. Our results show that in order to accurately determine vectorborne disease threats and the impact of control operations on these 2 species, multiple trapping techniques should be utilized when studying Ae. aegypti and Ae. albopictus population dynamics.

A Follow-Up to the Geographical Distribution of Anopheles Species in Malaria-Endemic and Non-Endemic Areas of Honduras.

Anopheles species are the vectors of malaria, one of the diseases with the greatest impact on the health of the inhabitants of the tropics. Due to their epidemiological relevance and biological complexity, monitoring of anopheline populations in current and former malaria-endemic areas is critical for malaria risk assessment. Recent efforts have described the anopheline species present in the main malaria foci in Honduras. This study updates and expands knowledge about Anopheles species composition, geographical distribution, and genetic diversity in the continental territory of Honduras as in the Bay Islands. Outdoor insect collections were carried out at 25 sites in eight municipalities in five departments of Honduras between 2018 and 2021. Specimens were identified using taxonomic keys. Partial COI gene sequences were used for molecular species identification and phylogenetic analyses. In addition, detection of Plasmodium DNA was carried out in 255 female mosquitoes. Overall, 288 Anopheles mosquitoes were collected from 8 municipalities. Eight species were morphologically identified. Anopheles albimanus was the most abundant and widely distributed species (79.5%). A subset of 175 partial COI gene sequences from 8 species was obtained. Taxonomic identifications were confirmed via sequence analysis. Anopheles albimanus and An. apicimacula showed the highest haplotype diversity and nucleotide variation, respectively. Phylogenetic clustering was found for An. argyritarsis and An. neomaculipalpus when compared with mosquitoes from other Neotropical countries. Plasmodium DNA was not detected in any of the mosquitoes tested. This report builds upon recent records of the distribution and diversity of Anopheles species in malaria-endemic and non-endemic areas of Honduras. New COI sequences are reported for three anopheline species. This is also the first report of COI sequences of An. albimanus collected on the island of Roatán with apparent gene flow relative to mainland populations.

Efficacy of ovitrap colors and patterns for attracting Aedes albopictus at suburban field sites in north-central Florida.

We sought to visually enhance the attractiveness of a standard black ovitrap routinely used in surveillance of the Asian tiger mosquito, Aedes albopictus, and now being used as lethal ovitraps in Ae. aegypti dengue control programs. Black plastic drinking cups (ovitraps) were visually altered to offer field populations of gravid female Ae. albopictus 6 different oviposition site choices. Trials were conducted at 3 field locations in Gainesville, Orange Park, and Jacksonville, FL, during July-August 2009. A black glossy cup served as the control and was tested against 5 cup choices consisting of white, blue, orange, or black-and-white contrasting patterns (checkered or vertically striped). Means (SE) of eggs collected over 6 wk for each choice were: black 122.53 (9.63) > blue 116.74 (10.74) > checkered 101.84 (9.53) > orange 97.15 (7.95) > striped 84.62 (8.17) > white 81.84 (8.74). Black ovitraps outperformed competing colored and contrasting patterned ovicups with respect to choice from gravid Ae. albopictus seeking artificial oviposition sites.

High Prevalence of Borrelia mayonii (Spirochaetales: Spirochaetaceae) in Field-Caught Tamias striatus (Rodentia: Sciuridae) From Northern Wisconsin.

Borrelia mayonii is a recently discovered bacterial spirochete that causes Lyme disease and is transmitted by the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae). To date, B. mayonii has been isolated from two vertebrate host species in Minnesota: field-caught white-footed mice (Peromyscus leucopus Rafinesque; Rodentia: Cricetidae) and American red squirrel (Tamiasciurus hudsonicus Erxleben). Here, we describe the first detection of B. mayonii in field-caught eastern chipmunks (Tamias striatus L. (Rodentia: Cricetidae)) from northern Wisconsin. During our study, we captured 530 unique small mammals and found an infection prevalence of 23.50% in field-caught eastern chipmunks (4/17) and 1.19% in Peromyscus spp. (5/420). Mean larval and nymphal burdens were determined for captured Blarina brevicauda (0, 0), Glaucomys volans (0.29, 0.14), Myodes gapperi (0.27, 0), Napaeozapus insignis (0, 0.25), Peromyscus spp. (1.88, 0.11), T. striatus (1.06, 0.65), and Sorex cinereus (0.09, 0). The high B. mayonii infection prevalence in eastern chipmunks suggests that the species may be an important reservoir for B. mayonii in the Upper Midwest.

The biological activity of alpha-mangostin, a larvicidal botanic mosquito sterol carrier protein-2 inhibitor.

alpha-Mangostin derived from mangosteen was identified as a mosquito sterol carrier protein-2 inhibitor via high throughput insecticide screening, alpha-Mangostin was tested for its larvicidal activity against third instar larvae of six mosquito species, and the median lethal concentration values range from 0.84 to 2.90 ppm. The residual larvicidal activity of alpha-mangostin was examined under semifield conditions. The results indicated that alpha-mangostin was photolytic with a half-life of 53 min in water under full sunlight exposure. The effect of alpha-mangostin on activities of major detoxification enzymes such as P450, glutathione S-transferase, and esterase was investigated. The results showed that alpha-mangostin significantly elevated activities of P450 and glutathione S-transferase in larvae, whereas it suppressed esterase activity. Toxicity of alpha-mangostin against young rats was studied, and there was no detectable adverse effect at dosages as high as 80 mg/kg. This is the first multifaceted study of the biological activity of alpha-mangostin in mosquitoes. The results suggest that alpha-mangostin may be a lead compound for the development of a new organically based mosquito larvicide.

Immature Ixodes scapularis (Acari: Ixodidae) Collected From Peromyscus leucopus (Rodentia: Cricetidae) and Peromyscus maniculatus (Rodentia: Cricetidae) Nests in Northern Wisconsin.

The blacklegged tick, Ixodes scapularis Say, is the primary Lyme disease vector in the eastern United States. Both immature stages of I. scapularis take blood meals from mice belonging to the genus Peromyscus. Mice are active during the night and spend the majority of diel periods in nests. Thus, immature I. scapularis have a greater opportunity to drop from Peromyscus hosts while in nests compared with the forest floor. Here, we collected 11 Peromyscus nests during a 3-mo period during which the immature I. scapularis are known to be active. We then examined nesting materials for the presence of I. scapularis. Immature I. scapularis were detected in 64% of Peromyscus nests examined. Additionally, 55% of the nests contained at least one Dermacentor variabilis Say larva. Eighty-seven percent of all larval ticks found within nests were blood-fed. Because Peromyscus spp. are highly competent reservoirs of numerous tick-borne pathogens, the ticks that detach in their nests may be important for the maintenance of tick-borne diseases. However, further studies are needed to determine the fate of the I. scapularis that detach in Peromyscus nests.

Larvicidal activity of sterol carrier protein-2 inhibitor in four species of mosquitoes.

A previous report has shown that mosquito sterol carrier protein-2 inhibitors (SCPIs) are larvicidal to larvae of the yellowfever mosquito, Aedes aegypti (L.) (J. Lipid Res. 46: 650-657, 2005). In the current study, we tested SCPI-1 in an additional four mosquito species for larvicidal activities: Culex pipiens pipiens, Anopheles gambiae, Culex restuans, and Aedes vexans. Cholesterol accumulation in SCPI-treated Ae. aegypti fourth instars was examined. SCPI-1 is lethal to all tested mosquito species, with the LC50 value ranging from 5.2 to 15 microM when treatments started at the first to third instar. However, LC50 values increase to from 5.2 to 38.7 microM in treatments started at first and fourth instar, respectively. The results indicate that the lethal effect of SCPI-1 decreases with the growth of larvae, which suggests that SCPI-1 is more effective before the larvae reach final growth period (the last instar). SCPI-1 suppressed cholesterol uptake in Ae. aegypti fourth instars, suggesting that one of the modes of action of SCPI-1 is via reduction in cholesterol absorption.