Making Mosquito Taxonomy Useful: A Stable Classification of Tribe Aedini that Balances Utility with Current Knowledge of Evolutionary Relationships

The tribe Aedini (Family Culicidae) contains approximately one-quarter of the known species of mosquitoes, including vectors of deadly or debilitating disease agents. This tribe contains the genus Aedes, which is one of the three most familiar genera of mosquitoes. During the past decade, Aedini has been the focus of a series of extensive morphology-based phylogenetic studies published by Reinert, Harbach, and Kitching (RH&K). Those authors created 74 new, elevated or resurrected genera from what had been the single genus Aedes, almost tripling the number of genera in the entire family Culicidae. The proposed classification is based on subjective assessments of the "number and nature of the characters that support the branches" subtending particular monophyletic groups in the results of cladistic analyses of a large set of morphological characters of representative species. To gauge the stability of RH&K's generic groupings we reanalyzed their data with unweighted parsimony jackknife and maximum-parsimony analyses, with and without ordering 14 of the characters as in RH&K. We found that their phylogeny was largely weakly supported and their taxonomic rankings failed priority and other useful taxon-naming criteria. Consequently, we propose simplified aedine generic designations that 1) restore a classification system that is useful for the operational community; 2) enhance the ability of taxonomists to accurately place new species into genera; 3) maintain the progress toward a natural classification based on monophyletic groups of species; and 4) correct the current classification system that is subject to instability as new species are described and existing species more thoroughly defined. We do not challenge the phylogenetic hypotheses generated by the above-mentioned series of morphological studies. However, we reduce the ranks of the genera and subgenera of RH&K to subgenera or informal species groups, respectively, to preserve stability as new data become available.

Economic evaluation of an area-wide integrated pest management program to control the Asian tiger mosquito in New Jersey

Aedes albopictus is the most invasive mosquito in the world, an important disease vector, and a biting nuisance that limits outdoor activities. Area-wide integrated pest management (AW-IPM) is the recommended control strategy. We conducted an economic evaluation of the AW-IPM project in Mercer and Monmouth Counties, New Jersey with a controlled design (AW-IPM vs. control) from 2009 through 2011. The study analyzed financial documents and staff time for AW-IPM and surveyed an average of 415 randomly chosen households in AW-IPM and control areas each fall from 2008 through 2011. Hours lost from yard and porch activities were calculated as differences between actual and potential hours of these activities in an average summer week if there had been no mosquito concerns. Net estimated benefits of AW-IPM were based on cross-over and difference-in-difference analyses. Reductions in hours lost were valued based on respondents' willingness to pay for a hypothetical extra hour free of mosquitoes spent on yard or porch activities and literature on valuation of a quality adjusted life year (QALY). The incremental cost of AW-IPM per adult was $41.18 per year. Number of hours lost due to mosquitoes in AW-IPM areas between the base year (2008) and the intervention years (2009-2011) declined by 3.30 hours per summer week in AW-IPM areas compared to control areas. Survey respondents valued this improvement at $27.37 per adult per summer week. Over the 13-week summer, an average adult resident gained 42.96 hours of yard and porch time, worth $355.82. The net benefit over the summer was $314.63. With an average of 0.0027 QALYs gained per adult per year, AW-IPM was cost effective at $15,300 per QALY gained. The benefit-cost ratio from hours gained was 8.64, indicating that each $1 spent on AW-IPM gave adults additional porch and yard time worth over $8.

Quantifying the impact of mosquitoes on quality of life and enjoyment of yard and porch activities in New Jersey

The recent expansion of Aedes albopictus, a day-biting mosquito, to densely inhabited areas in the northeastern Atlantic states of the USA has dramatically increased the problem that mosquitoes create for urban and suburban residents. We quantified the impact of mosquitoes on residents' quality of life within the context of a comprehensive area-wide integrated pest management program to control Ae. albopictus in two counties (Mercer and Monmouth) in New Jersey. We interviewed residents of 121 randomly selected households in both counties between October and November 2010. We asked residents about their experience with mosquitoes in their neighborhood and the importance of the ability to relax outdoors without mosquitoes compared to other neighborhood characteristics (1 = not important, 5 = extremely important). We rated residents' utility based on paired comparisons to known states from the EuroQol health description system. The majority (54.6%) of respondents considered mosquitoes to be a problem. Respondents reported an average of 7.1 mosquito bites in a typical week during that summer. Mosquitoes prevented 59.5% of residents from enjoying their outdoor activities at least to some extent. Residents rated the mosquito acceptability (mean ± standard deviation) during that summer on a scale of 0 (mosquito invasion) to 100 (no mosquitoes) at 56.7±28.7, and their overall utility at 0.87±0.03. This is comparable to living with up to two risk factors for diabetes (i.e., abdominal obesity, body mass index of 28 or more, reported cholesterol problems, diagnosis of hypertension, or history of cardiovascular disease) or women experiencing menstrual disorders. Respondents rated the importance of enjoying outdoor activities without mosquitoes (4.69±0.80) comparable to that of neighborhood safety (4.74±0.80) and higher than that of a clean neighborhood (4.59±0.94). In conclusion, New Jersey residents reported that mosquitoes decreased their utility by 0.13, comparable to the loss from worrisome health risk factors, underscoring the importance of controlling this problem.

One Health approach to identify research needs in bovine and human babesioses: workshop report

BACKGROUND

Babesia are emerging health threats to humans and animals in the United States. A collaborative effort of multiple disciplines to attain optimal health for people, animals and our environment, otherwise known as the One Health concept, was taken during a research workshop held in April 2009 to identify gaps in scientific knowledge regarding babesioses. The impetus for this analysis was the increased risk for outbreaks of bovine babesiosis, also known as Texas cattle fever, associated with the re-infestation of the U.S. by cattle fever ticks.

RESULTS

The involvement of wildlife in the ecology of cattle fever ticks jeopardizes the ability of state and federal agencies to keep the national herd free of Texas cattle fever. Similarly, there has been a progressive increase in the number of cases of human babesiosis over the past 25 years due to an increase in the white-tailed deer population. Human babesiosis due to cattle-associated Babesia divergens and Babesia divergens-like organisms have begun to appear in residents of the United States. Research needs for human and bovine babesioses were identified and are presented herein.

CONCLUSIONS

The translation of this research is expected to provide veterinary and public health systems with the tools to mitigate the impact of bovine and human babesioses. However, economic, political, and social commitments are urgently required, including increased national funding for animal and human Babesia research, to prevent the re-establishment of cattle fever ticks and the increasing problem of human babesiosis in the United States.

Topically applied AaeIAP1 double-stranded RNA kills female adults of Aedes aegypti

Aedes aegypti (L.) (Diptera: Culicidae) is the primary vector of both dengue and yellow fever. Use of insecticides is one of the primary ways to control this medically important insect pest. However, few new insecticides have been developed for mosquito control in recent years. As a part of our effort to develop new insecticides to control mosquitoes, an inhibitor of apoptosis protein 1 gene in Aedes aegypti (AaeIAP1) was targeted for the development of molecular pesticides. Herein, for the first time, we report that topically applied AaeIAP1 double-stranded RNA products are able to kill female adults of Ae. aegypti. Our results indicate that critical pathways or genes could be targeted to develop molecular pesticides for the control of medically important diseases vectors.

A Rift Valley fever risk surveillance system for Africa using remotely sensed data: potential for use on other continents

The authors developed a monitoring and risk mapping system using normalized difference vegetation index (NDVI) times series data derived from the advanced very high resolution radiometer (AVHRR) instrument on polar orbiting national oceanographic and atmospheric administration (NOAA) satellites to map areas with a potential for a Rift Valley fever (RVF) outbreaks in sub-Saharan Africa. This system is potentially an important tool for local, national and international organisations involved in the prevention and control of animal and human disease, permitting focused and timely implementation of disease control strategies several months before an outbreak. We are currently developing a geographic information system (GIS)-based remotely sensed early warning system for potential RVF vectors in the United States. Forecasts of the potential emergence of mosquito vectors will be disseminated throughout the United States, providing several months' warning in advance of potentially elevated mosquito populations. This would allow timely, targeted implementation of mosquito control, animal quarantine and vaccine strategies to reduce or prevent animal and human disease.

Occurrence of Orientia tsutsugamushi in small mammals from Thailand

Extensive sampling of small mammals was conducted in eight provinces of Thailand between September 9, 1992 and April 29, 2001. A total of 3,498 specimens representing 22 species were collected. Eighty-eight percent (3,089 of 3,498) of the animals were collected from a region in Chiangrai Province, which is commonly recognized as endemic for human scrub typhus. Blood and tissue samples from each animal were tested for the presence of Orientia tsutsugamushi, the etiologic agent of scrub typhus. The predominant species collected were Rattus rattus (53%, n = 1,863), R. losea (18%, n = 638), Bandicota indica (16%, n = 564), and R. exulans (4%, n = 146). Orientia tsutsugamushi was detected in 10 of the 22 species of mammals that included R. bukit (25% infected, 1 of 4), R. rattus (23%, 419 of 1,855), R. argentiventer (22%, 5 of 23), R. berdmorei (22%, 2 of 9), R. losea (13%, 82 of 638), B. indica (9%, 52 of 564), R. koratensis (8%, 1 of 12), B. savilei (3%, 1 of 30), R. exulans (1%, 2 of 146), and Tupaia glis (2%, 1 of 49). Infected animals were found in Chiangrai (18% infected, 563 of 3,084), Bangkok (11%, 1 of 9), Sukothai (3%, 1 of 30), and Nonthaburi (1%, 1 of 69) Provinces. The implications towards scrub typhus maintenance and transmission are discussed.

Plasmodium berghei: sensitivity of chloroquine-resistant and chloroquine-sensitive strains to irradiation and the effect of irradiated malaria parasites on cytochrome P450-dependent monooxygenases

Differences in sensitivities of chloroquine-sensitive and chloroquine-resistant strains of Plasmodium berghei were observed following irradiation of the parasites. A dose of 15 kilorads from a cobalt-60 source killed the erythrocytic stages of the chloroquine-sensitive strain and no parasitemias were observed when mice were injected with these irradiated parasites. In contrast, when the chloroquine-resistant strain was irradiated with the same dose of cobalt-60 and injected into mice, an infection rate of 12.5% was observed, indicating that the latter strain was more resistant to inactivation by irradiation. Following injection of these irradiated strains of P. berghei into mice, significant decreases in mouse hepatic cytochrome P450 and benzo(a)pyrene hydroxylase activity, with no significant effect on N-demethylase activity, were observed. Serum glutamic-oxaloacetic transaminase (SGOT) and glutamic-pyruvic transaminase (SGPT) levels of mice injected with the irradiated parasites fell within the range of the serum enzyme levels in normal laboratory mice.