Fiona F. Hunter

Establishment of Ochlerotatus japonicus (Diptera: Culicidae) in Ontario, Canada

Abstract Ochlerotatus (Finlaya) japonicus (Theobold) is newly established in Ontario, Canada. It was first discovered in 2001 during the province-wide West Nile virus mosquito surveillance program implemented by the Ontario Ministry of Health and Long Term Care. Although the numbers of adults trapped in CDC light traps were low in 2001 and 2002, they increased during the 2003 and 2004 surveillance seasons. Oc. japonicus larvae also have been collected in large numbers in the Niagara Peninsula in a variety of natural and artificial containers. The number of health units with records for Oc. japonicus has increased over the 4 yr of surveillance, illustrating the ability of this species to rapidly extend its range. As a potential arboviral bridge vector, its establishment in Ontario requires further study and should be considered a public health concern.

Attraction of Culex pipiens/restuans (Diptera: Culicidae) Mosquitoes to Bird Uropygial Gland Odors at Two Elevations in the Niagara Region of Ontario

Abstract In an effort to determine whether female Culex pipiens L. and Culex restuans Theobald mosquitoes (Diptera: Culicidae) are attracted to crow, Corvus brachyrhynchus, uropygial gland secretions, CDC miniature light traps (baited with CO2 but with the lights removed) were placed at ≈1.5- and 5-m elevations, in 10 trees in a woodlot near Niagara Falls, Canada. These traps were assigned either a bird odor or a blank control. Bird odors were created by attaching cotton swabs coated with crow uropygial gland secretions to the trap intake. A significantly greater number of Cx. pipiens/restuans were found in the 5-m traps compared with 1.5-m traps, with a significant number attracted to the bird odor over the no odor traps at the 5-m elevation, but not at 1.5 m. We also found more Aedes vexans (Meigen) in the 1.5-m traps than the 5-m traps; however, presence or absence of bird odor did not influence the distribution of Ae. vexans.

End‐products of behaviour versus behavioural characters: a phylogenetic investigation of pupal cocoon construction and form in some North American black flies (Diptera: Simuliidae)

Cocoon spinning was analysed, using video recording and playback, in eighteen Nearctic black fly species, comparing nine Simulium species, six Eusimulium species, Stegopterna mutata, Cnephia dacotensis and Prosimulium mixtum. Fourteen behavioural characters were revealed that produced twenty‐two equally parsimonious trees (CI = 0.93, RI = 0.96). Another tree was constructed on the basis of five characters relating to the cocoon structure (end‐product characters). The goal of the study was to determine whether characters relating to behavioural components of black fly cocoon spinning or those based on end‐products of the behaviour are superior for revealing phylogenetic relationships. This was accomplished by comparing both data sets to a phylogeny constructed with the use of cytological and morphological characters. If taxa are grouped according to end‐products (the cocoons) there are some spurious groupings. The behavioural analysis only required one extra step to duplicate the morphological and cytological tree. In the case of black flies, it is more informative to use characters resulting from the analysis of the cocoon spinning behaviour than cocoon morphology.

New highland distribution records of multiple Anopheles species in the Ecuadorian Andes

BackgroundSeveral recent climate change reviews have stressed the possibility of some malaria vectors occupying regions of higher altitudes than previously recorded. Indeed, highland malaria has been observed in several African nations, possibly attributable to changes in land use, vector control and local climate. This study attempts to expand the current knowledge of the distribution of common Anopheles species in Ecuador, with particular attention to highland regions (> 500 m) of the Andes.MethodsExtensive field collections of larvae were undertaken in 2008, 2009 and 2010 throughout all regions of Ecuador (except the lower-altitude Amazonian plain) and compared to historical distribution maps reproduced from the 1940s. Larvae were identified using both a morphological key and sequencing of the 800 bp region of the CO1 mitochondrial gene. In addition, spatial statistics (Getis-Ord Hotspot Analysis: Gi*) were used to determine high and low-density clusters of each species in Ecuador.ResultsDistributions have been updated for five species of Anopheles in Ecuador: Anopheles albimanus, Anopheles pseudopunctipennis, Anopheles punctimacula, Anopheles eiseni and Anopheles oswaldoi s.l.. Historical maps indicate that An. pseudopunctipennis used to be widespread in highland Andean valleys, while other species were completely restricted to lowland areas. By comparison, updated maps for the other four collected species show higher maximum elevations and/or more widespread distributions in highland regions than previously recorded. Gi* analysis determined some highland hot spots for An. albimanus, but only cold spots for all other species.ConclusionsThis study documents the establishment of multiple anopheline species in high altitude regions of Ecuador, often in areas where malaria eradication programs are not focused.

Characterization of Larval Habitats of Anopheles albimanus, Anopheles pseudopunctipennis, Anopheles punctimacula, and Anopheles oswaldoi s.l. Populations in Lowland and Highland Ecuador

ABSTRACT: Recent collection data indicate that at least four potential malaria vectors occupy more widespread distributions within the Andean highlands than in the past. Since habitat elimination is an important aspect of malaria control, it is vital to characterize larval habitats for Anopheles species within both lowland and highland sites. To that end, 276 sites within Ecuador were surveyed between 2008 and 2010. Characteristics of Anopheles-present sites for four species were compared to Anopheles-absent sites within the same geographical range and also to Anopheles-absent sites within a highland range representing potential future habitats. Thermochron iButtons© were used to describe the daily temperature variation within a subset of potential habitats. Anopheles albimanus (W.) was positively associated with permanent habitats, sand substrates, floating algae (cyanobacterial mats), and warmer temperatures in both comparisons. Anopheles pseudopunctipennis (T.) was associated with floating algae (cyanobacterial mats), warmer temperatures, and higher water clarity in both comparisons. Anopheles punctimacula (D.&K.) was negatively associated with floating algae and positively associated with dissolved oxygen in both comparisons. Anopheles oswaldoi s. l. (P.) was not significantly associated with any parameters more often than expected given larval-absent sites. The results indicate that minimum water temperatures might limit the upper altitudinal distribution of An. albimanus (18.7° C) and An. pseudopunctipennis (16.0° C).

Do gravid black flies (Diptera: Simuliidae) oviposit at their natal site?

We present information on an aniline dye marking method for black flies. In the laboratory, adults were sprayed with 2% aqueous solutions of four colors of aniline dyes; brilliant blue and methyl orange gave the best results in longevity trials. In field trials we were able to recapture 1.3% of newly emerged marked and released flies at oviposition sites. Mark–release–recapture experiments were designed to distinguish among three competing models concerning oviposition site selection by gravid female black flies: (1) larval site fidelity (“Do flies return to the site that they experienced as larvae?”), (2) adult site fidelity (“Do flies return to the site that they experienced as adults?”), and (3) no site fidelity (“Do flies oviposit at random, i.e., without regard to adult or larval experience?”). Models 1 and 2 were rejected. There is, however, no reason to reject Model 3, the no site fidelity model. Thus, we conclude that for members of the S. venustum/verecundum complex (i.e., S. rostratum, S. venustum, and S. truncatum) females find an “apparently suitable” waterway in which to oviposit; this may or may not be their natal site.

Using behavioural characters in phylogeny reconstruction

Behaviour remains underrepresented in phylogeny reconstruction, possibly because the term ‘behaviour’ incorporates a wide range of phenomena, not all of which are equally applicable to understanding evolutionary history. We assessed the character homology (i.e., potential problems with coding) and homoplasy (i.e., lability or convergence) for each of four types of behaviour (behavioural categories, reaction stimuli traits, the specific movements of animals and quantitative information relating to each of these behaviour types) and determined the broad applicability of each behavioural type for phylogeny reconstruction. When using behaviour to reconstruct a phylogeny we recommend the following order of behavioural types: (1) animal movements; (2) quantitative components (providing that the animal movements are homologous); (3) reaction stimuli traits; (4) behavioural categories.

West Nile virus in Ontario, Canada: A twelve-year analysis of human case prevalence, mosquito surveillance, and climate data

West Nile Virus (WNV) first arrived in Ontario, Canada in 2001 and has since spread throughout most of the province, causing disease in humans. The provincial government established a province-wide surveillance program to monitor WNV transmission throughout the 36 regional health units. Here we have acquired records of WNV human and mosquito surveillance from 2002 to 2013 to describe seasonal and geographic trends in WNV activity in southern Ontario. Additionally, we obtained climate data from seven municipalities to investigate how temperature and precipitation affect WNV transmission dynamics. We identified a strong quadratic relationship between the number of confirmed human cases and positive Culex mosquito pools recorded at the end of each year (R2 = 0.9783, p < 0.001). Using Spearman rank correlation tests, we identified that the minimum infection rate of Culex pipiens/restuans pools are the strongest predictor of human cases at a 1 week lag period. We also identified positive correlations between minimum infection rates, temperature, vector abundance, and cumulative precipitation. Global Moran’s I index indicates strong positive autocorrelation and clustering of positive Culex pool counts in southern Ontario. Local indicators of spatial association tests revealed a total of 44 high-high and 1 high-low trap locations (n = 680). In the current work we have identified when and where hot spots of WNV activity have occurred in southern Ontario. The municipalities surrounding the western shore of the Lake Ontario and Windsor-Essex County have the largest records of positive mosquitoes and human cases. We identified that positive mosquitoes are a strong indicator of human cases to follow in the coming weeks. An epidemic action threshold of cumulative positive Culex pools was established, allowing Ontario public health officials to predict an epidemic at epidemiological week 34 (rho = 0.90, p < 0.001). These data have the potential to contribute to more efficient larvicide programs and awareness campaigns for the public.

Larval Habitat Associations with Human Land Uses, Roads, Rivers, and Land Cover for Anopheles albimanus, A. pseudopunctipennis, and A. punctimacula (Diptera: Culicidae) in Coastal and Highland Ecuador

Larval habitat for three highland Anopheles species: Anopheles albimanus Wiedemann, Anopheles pseudopunctipennis Theobald, and Anopheles punctimacula Dyar and Knab was related to human land uses, rivers, roads, and remotely sensed land cover classifications in the western Ecuadorian Andes. Of the five commonly observed human land uses, cattle pasture (n = 30) provided potentially suitable habitat for A. punctimacula and A. albimanus in less than 14% of sites, and was related in a principal components analysis (PCA) to the presence of macrophyte vegetation, greater surface area, clarity, and algae cover. Empty lots (n = 30) were related in the PCA to incident sunlight and provided potential habitat for A. pseudopunctipennis and A. albimanus in less than 14% of sites. The other land uses surveyed (banana, sugarcane, and mixed tree plantations; n = 28, 21, 25, respectively) provided very little standing water that could potentially be used for larval habitat. River edges and eddies (n = 41) were associated with greater clarity, depth, temperature, and algae cover, which provide potentially suitable habitat for A. albimanus in 58% of sites and A. pseudopunctipennis in 29% of sites. Road-associated water bodies (n = 38) provided potential habitat for A. punctimacula in 44% of sites and A. albimanus in 26% of sites surveyed. Species collection localities were compared to land cover classifications using Geographic Information Systems software. All three mosquito species were associated more often with the category “closed/open broadleaved evergreen and/or semi-deciduous forests” than expected (P ≤ 0.01 in all cases), given such a habitat’s abundance. This study provides evidence that specific human land uses create habitat for potential malaria vectors in highland regions of the Andes.

Malaria in Highlands of Ecuador since 1900

Eliminated after 1950, malaria may be reemerging in a new region.