A Viability Assessment of Two Commercially Available Sticking Adjuvants Added to a Bifenthrin-Based Barrier Treatment on Aedes taeniorhycnhus

ABSTRACT In an effort to reduce Aedes taeniorhynchus numbers in the northernmost community of Key Largo, FL (known as Ocean Reef), during the peak summer months, Florida Keys Mosquito Control District (FKMCD) has utilized a bifenthrin-based barrier application (Wisdom TC Flowable®) for several years. The FKMCD conducted a study comparing whether 2 aftermarket wetting/sticking adjuvants could improve the efficacy of the barrier treatments used to control Ae. taeniorhynchus. Maximum label rate was used for 3 separate solutions: Wisdom TC Flowable (1 fl oz/gal [7.81 ml/liter] water) with no additives (Wisdom), Wisdom with Lesco Spreader-Sticker® (0.08 fl oz [2.37 ml]), and Wisdom with Xtended Performance® (2.56 fl oz [75.71 ml]). All solutions were applied to 100-ft (approximately 3 m) sections of tree-lined roadways in Key Largo, FL, using a SR 420® Mistblower backpack sprayer (Stihl Corp.). Leaves were collected from each application area for 8 consecutive weeks. Leaves were used to perform leaf bioassays against local populations of Ae. taeniorhynchus adults, and mortality was recorded at 1, 4, and 24 h postexposure. This process was replicated 3 times. Treatments had variable mortality rates at 1, 4, and 24 h postexposure across 7 wk following application. Mortality rates for all mixtures decreased for all exposure times throughout the study. Overall, the Lesco Spreader-Sticker solution was the only combination with a positive significant difference in adult mortality after 24 h.

La trampa entomológica Gravid-Aedes Trap, como una alternativa para el monitoreo del mosquito Aedes aegypti, vector del dengue, en las islas Galápagos

El mosquito Aedes aegypti es un insecto díptero de importancia médica y es vector de varios arbovirus, entre ellos el dengue, el chikungunya y el Zika. Esta especie es diurna y está adaptada a vivir cerca del ser humano en ambientes urbanos. En 1988 ocurrió el primer brote epidémico de dengue en Ecuador. Desde entonces, es endémico y ocasiona picos de transmisión cada cuatro o cinco años. En las islas Galápagos, el dengue fue introducido en 2002, cuando se reportaron los primeros casos en la isla Santa Cruz. Luego, un brote epidémico de magnitud ocurrió en 2010 en la isla San Cristóbal y, desde entonces, se reportan casos esporádicos cada año. Pocos casos de chikungunya y de Zika también han sido reportados. En el archipiélago, las medidas para controlar a la población de mosquitos se restringen al control vectorial mediante abatización que elimina las larvas, y fumigación con el insecticida Deltametrina para matar a los adultos. Actualmente, no hay un sistema de monitoreo rutinario de las poblaciones de mosquitos, que se considera crucial para evaluar los métodos de control más adecuados y adoptar las medidas más convenientes para combatir al mosquito vector y disminuir la transmisión de enfermedades. Se presenta la trampa Gravid-Aedes Trap (GAT) como una herramienta de monitoreo pasivo y fácil de usar. Su precio es asequible y no requiere de una fuente de electricidad para funcionar. Estudios de evaluación en Brasil muestran la utilidad de esta trampa para el monitoreo y también para el control vectorial. Se reporta un estudio piloto con 10 trampas GAT que se colocaron en Puerto Baquerizo Moreno, en la isla San Cristóbal, y en Puerto Ayora, en Santa Cruz, para monitorear mosquitos. Los resultados preliminares sugieren que esta metodología puede ser efectiva para colectar Aedes aegypti y, por tanto, de potencial utilidad para complementar las estrategias de control vectorial que se llevan a cabo rutinariamente en las islas Galápagos. Otras especies de mosquitos colectadas fueron Culex quinquefasciatus y Aedes taeniorhynchus. Son necesarios estudios a mayor escala para seguir evaluando la utilidad de esta nueva trampa.

COMPARATIVE EFFICACY OF FIVE PERMETHRIN/ PBO 30-30 GROUND ULV INSECTICIDES AGAINST FIELD COLLECTED ADULT AEDES AEGYPTI, AEDES TAENIORHYNCHUS, AND CULEX QUINQUEFASCIATUS IN MANATEE COUNTY, FLORIDA

We investigated five formulations containing synergized permethrin/PBO active ingredients, Biomist® 30-30, Evoluer® 30-30, Kontrol™ 30-30, Permanone® 30-30, and Perm-X™ UL 30-30, to determine whether there was variation in efficacy against caged local field collected adult Aedes aegypti, Aedes taeniorhynchus, and Culex quinquefasciatus mosquitoes. Mortality data from field trials with these formulations applied via truck mounted ultra-low volume sprays at mid (113 mL/ha [1.55 oz/A]) and maximum (226 mL/ha [3.10 oz/A]) label rates indicated generally low efficacy against Ae. aegypti and Cx. quinquefasciatus but generally high efficacy against Ae. taeniorhynchus. We discuss potential underlying mechanisms for this variation including effects of meteorology and resistance, and how field-derived efficacy data may be used operationally by mosquito and vector control districts to mitigate cost, environmental impact, and pesticide resistance.

EVALUATION OF CDC LIGHT TRAP, BG SENTINEL TRAP, AND MMX TRAP FOR THE COLLECTION OF SALT MARSH MOSQUITOES IN ANASTASIA STATE PARK, SAINT AUGUSTINE, FLORIDA

Salt marsh mosquitoes are major nuisance pests during the periods of high mosquito activity, especially after major storm events. In 2016-2017, Saint John’s County, Florida, USA was struck by two major hurricanes that resulted in multiple outbreaks of salt marsh mosquito populations. To optimize the surveillance of two salt marsh mosquitoes, (Aedes taeniorhynchus and Ae. sollicitans, three types of traps (the Centers for Disease Control (CDC) Light trap, Biogents Sentinel (BG) trap and Counter Flow Geometry Model (MMX) trap were tested for their capacity to capture the highest numbers of high quality live specimens for laboratory bioassays. Each trap type was tested in Anastasia State Park, located along a major salt marsh area in Saint John’s County. Although the MMX trap captured most of the salt marsh mosquitoes collected, the numbers of mosquitoes captured was not statistically significant compared to the other trap types. However, there was a significant difference in the numbers between Ae. taeniorhynchus and Ae. sollicitans in the MMX traps. The MMX trap is preferred for capturing salt marsh mosquitoes that are in high quality for the CDC bottle bioassays.

VARIACIÓN DE INDICADORES ENTOMOLÓGICOS DE AEDES AEGYPTI Y OTROS CULÍCIDOS (DIPTERA: CULICIDAE) EN DOS PARQUES MUNICIPALES DE LA PROVINCIA DE LIMA, PERÚ

La evaluación de Aedes aegypti (Linnaeus, 1762) y otros culícidos (Díptera: Culicidae) en parques zonales (PZ ) de Lima Metropolitana, Perú con técnicas entomológicas permite obtener información para s la prevención de enfermedades transmitidas por mosquitos en Salud Pública. El objetivo del presente trabajo fue evaluar la variación de indicadores entomológicos (IE ) de A. aegypti y otros culícidos s (Diptera: Culicidae) en dos parques municipales de la provincia de Lima, Perú. El estudio se realizó en dos PZ de los distritos de Comas – PZSR (Parque Zonal Sinchi Roca) y Villa El Salvador – PZH (Parque zonal s Huascar), Lima, Perú. Se identificaron cuatro especies de culícidos: A. aegypti, Anopheles pseudopunctipennis Theobald, 1901, Culex quinquefasciatus (Say, 1823) and Aedes taeniorhynchus (Wiedemann, 1821). La variación de los IE para ambos PZ es marcada entre noviembre hasta marzo para s s todos los culícidos, con excepción de A. aegypti que presentó índices elevados solo en mayo. Además el índice de recipientes es elevado en julio para PZSR y en febrero para PZH. Se identificó como criadero potencial a los canales y sumideros de caño construidos de concreto con positividad elevada y significativa en ambos PZ . Se establecieron IE por áreas para zonas no residenciales o no urbanas como s s los PZ , basados en IE usados para A. aegypti y empleados para evaluar las variaciones de culícidos en el s s presente trabajo.

Taxonomy, ecology and distribution of the mosquitoes (Diptera: Culicidae) of the Dutch Leeward Islands, with a key to the adults and fourth instar larvae

Assessing mosquito biodiversity is important for disease surveillance and ecosystem health assessments. Such studies are particularly needed in regions like the Caribbean, which have experienced a series of recent mosquito borne disease outbreaks but received little attention regarding its invertebrate biodiversity. Here, we report on results from a mosquito survey on the Dutch Leeward Islands (Sint Eustatius, Sint Maarten and Saba), carried out in April and October 2018, which is the first integrative survey since those conducted by Van der Kuyp (1947) and Wagenaar Hummelinck (1949). Moreover, we present a novel key for adults and fourth instar larvae of the mosquitoes of the Dutch Leeward Islands. Overall, eleven species were recorded, eight on Sint Maarten, five on Saba and two on Sint Eustatius. Two new potential disease vectors, Culex nigripalpus and Aedes taeniorhynchus, were recorded on Sint Maarten. One previously recorded species, Cx. habilitator, was not retrieved from any of the islands, which is further discussed in the paper. Species indicative of natural forest which previously occurred on all three islands were absent from Sint Eustatius and Sint Maarten but still present on Saba. In contrast, species indicative of human inhabitation, Ae. aegypti and Cx. quinquefasciatus, were highly abundant on Sint Maarten and Sint Eustatius and present in low numbers on Saba. Overall, the results of this study emphasize the importance of biodiversity surveys and indicate that frequent mosquito inventories may contribute to a better understanding of mosquito community composition and distribution of potential vector species.

Assessing the blood meal hosts of Culex quinquefasciatus and Aedes taeniorhynchus in Isla Santa Cruz, Galápagos

Background Blood meal host selection by mosquito vectors is an important component in understanding disease dynamics of pathogens that threaten endemic fauna in isolated islands such as Galápagos. Research on the feeding behavior of mosquitoes can provide clues to the hosts and vectors involved in disease transmission. This information is particularly critical for endemic wildlife fauna in island systems that have evolved without resistance to novel diseases such as avian malaria. The aims of this study were to determine the blood-feeding patterns of two species of mosquitoes found in Galápagos and discuss how their feeding behavior may influence the transmission of pathogens such as avian malaria. Methods In the summer of 2015, we sampled two mosquito species (Aedes taeniorhynchus and Culex quinquefasciatus) across 18 different sites on Isla Santa Cruz, which is the second largest island in Galápagos and has the largest human population. We trapped mosquitoes using CDC light traps and CDC gravid traps and identified sources of blood meals for engorged mosquitoes by sequencing a portion of the vertebrate mitochondrial cytochrome b gene. Results Out of 947 female mosquitoes captured, 320 were blood-fed, and PCR amplifications were successful for 301 of the blood meals. Results revealed that both Aedes taeniorhynchus and Culex quinquefasciatus feed from a variety of vertebrate taxa, numerically dominated by humans on Isla Santa Cruz. Conclusions The high proportion of mammalian blood meals could represent locally available and abundant hosts on Santa Cruz. However, host surveys and estimates of relative abundances of vertebrate species will need to accompany mosquito trapping studies on non-inhabited and inhabited islands in Galápagos to further validate this.