Rubén Bueno-Marí

Classification of Spanish Mosquitoes in Functional Groups

Abstract We present a classification of Spanish mosquitoes according to their different life cycles. The bio-ecological parameters analyzed in our study were oviposition sites, overwintering stages, preferred hosts, and number of generations per year for each species. The results revealed 13 different functional groups. To assess the validity and robustness of the classification system, we analyzed the data from an intensive sampling carried out over a period of 4 years (2005–08) in eastern Spain. In this area, 9 of the 13 functional groups were found. The Jaccard cluster and the principal components analysis (between-group analysis method) revealed 3 different mosquito groups: the tree hole species, the aedine species (except dendrolimnic ones), and the rest of the non-dendrolimnic culicid species. The importance of the different overwintering patterns in distinguishing these 3 classes is also discussed.

Editorial: Emerging Zoonoses: Eco-Epidemiology, Involved Mechanisms, and Public Health Implications

Zoonoses are currently considered as one of the most important threats for Public Health worldwide. Zoonoses can be defined as any disease or infection that is naturally transmissible from vertebrate or invertebrate animals to humans and vice-versa. Approximately, 75% of recently emerging infectious diseases affecting humans are diseases of animal origin; approximately, 60% of all human pathogens are zoonotic. All types of potential pathogenic agents, including viruses, parasites, bacteria, and fungi, can cause these zoonotic infections. From the wide range of potential vectors of zoonoses, arthropods are probably those of major significance due to their abundance, high plasticity, adaptability, and coevolution to different kinds of pathogens, high degrees of synanthropism in several groups, and difficulties to apply effective programs of population control. Although ticks, flies, sandflies, cockroaches, bugs, and fleas are excellent vectors capable of transmitting viruses, parasites, and bacteria, undoubtedly mosquitoes are the most important human disease vectors, while ticks are the most important vectors of pathogens in domestic production animals. Mosquito borne diseases like malaria, equine encephalitis, or West Nile are zoonoses with increasing incidence in the last years in tropical and temperate countries. All these zoonoses are thoroughly discussed in the Research Topic (1–5). Moreover, several researches focused on new tools to fight against Dengue vectors (6), studies about mosquito biodiversity (7), or novel modeling techniques based on climatic factors to predict vector’s incidence (8) can also be found in our compilation of research works related with zoonoses. Although it is well known that mosquitoes are the major vectors worldwide, probably ticks and tick-borne diseases are those that have aroused higher interest in epidemiologists and medical entomologists in recent years (9–12).

Global change and human vulnerability to vector-borne diseases

This e-book presents a collection of research and review articles related to the spread, control and basic understanding of vector borne diseases all over the world. It is well known that a multidisciplinary point of view is necessary in order to develop a global vision of this emergent problem. Therefore, in order to promote this holistic approach to the knowledge of vector borne diseases, this e-book contains a total of 19 collaborations of entomologists, epidemiologists, virologists, parasitologists, bacteriologists, zoologists and veterinarians of Europe, Africa, Asia, and America. The title perfectly reflects some of the global factors that are behind the emergence and/or reemergence of vector borne diseases. It is now well known that several climatic, environmental and sociodemographic changes that have occurred over the past years are some of the most important causes for the resurgence of many diseases worldwide. However, global change, defined as the impact of human activity on the fundamental mechanisms of biosphere functioning, includes not only climate change, but also habitat transformation, water cycle modification, biodiversity loss, synanthropic incursion of alien species into new territories, or the introduction of new chemicals in nature. Although there is a large and varied group of vectors worldwide, in this e-book we have examined the two most important disease vectors in our opinion: mosquitoes and ticks. Studies about the presence and transmission rates of viruses like West Nile, assays about mosquito control with new and encouraging methods, studies related to the importance of vector control strategies, research results about the role of asymptomatic cases of anthroponosis like Dengue, and investigations about the impact of climate trends on diseases transmitted by ticks and mosquitoes, are some of the issues that can be found in this Research Topic. As editors of this Research Topic, we would like to acknowledge sincerely all coauthors for their valuable and interesting contributions and we wish the readers of this e-book a productive and enjoyable reading of some of the most innovative work related to vector borne diseases.

Looking for new strategies to fight against mosquito-borne diseases: toward the development of natural extracts for mosquito control and reduction of mosquito vector competence

This commentary highlights key points, basic ideas, and future outlooks presented by Eastep et al. (2012) in Frontiers in Physiology-Systems Biology. The authors have provided an interesting investigation about the successful use of an environmentally friendly product derived from plants as a larvicidal agent to control mosquito populations as well as a substance that could alter the vector competence of mosquitoes for arthropod-borne viruses (arboviruses). Specifically Eastep and collaborators used coffee extracts (with and without caffeine) to try to answer two hypothesis: first, coffee extracts could have good results as a mosquitocidal compounds applied in larval biotopes and second, virus replication can be modulated in adult mosquitoes by exposing the larvae to sublethal concentrations of coffee extracts. Detailed information about results and methodology can be found in that article, but we can anticipate that both hypotheses were affirmative confirmed. Although some aspects remained unknown and must be further analyzed, e.g., the specific identification of the active agent or agents responsible for the observed effects, these preliminary results provide a new and hopeful way of fight against mosquito-borne viruses, since two flanks of the complex eco-epidemiological cycle of arbovirus can be attacked: density decrease of disease vectors and reduction/inhibition of the virus replication mosquitoes. However, the influence of coffee extracts exposure on vectorial capacity (VC) of mosquitoes must be carefully analyzed, since VC depends of a great variety of parameters such as vector density, host feeding preference, number of gonotrophic cycles, adult survival, or extrinsic incubation period, among others. Despite Eastep and colleagues detected high mortality in mosquito larvae exposed to coffee extracts, it must be noted that the same authors also evidenced that females reared in coffee tended to lay more eggs than control females, which could theoretically lead to a higher risk of virus transmission by increasing the vector density at medium or long term. Therefore, possible adverse implications of larval biotopes alterations by applying coffee extracts should be deeply and meticulously studied. It is interesting to note that mosquito species selected to carry out the assays was Aedes albopictus (Skuse, 1894), which is currently one of the most important threats for public health all over the world due to its invasive behavior and potential to transmit a great broad of diseases including some devastating viruses for human population such as Dengue, Yellow Fever, or Chikungunya (Bueno Mari and Jimenez Peydro, 2012). However, none of these tropical and anthroponotic viruses were selected to test the antiviral experiments. The virus employed was La Crosse virus (LACV), which is a zoonotic virus of Bunyaviridae family that usually involves chipmunks and accidentally humans, where infections are common in non-tropical countries like United States of America (USA) but disease is not frequent and symptoms are generally of low severity causing occasionally encephalitis and very rarely death (Borucki et al., 2002; Haddow and Odoi, 2009). Nevertheless, some references about antiviral activity of plant extracts against other mosquito-borne diseases such as Dengue (Tang et al., 2012), Yellow Fever (Ojo et al., 2009), or Ross River Fever (Semple et al., 1998), among others, can be found in literature. The paper of Eastep and collaborators affects to an important issue nowadays for public institutions and private companies responsible for mosquito control campaigns: the development of natural insecticides with scanty resistance effects and low toxicity to humans and non-target organisms of aquatic environments. Mosquito resistance is currently an increasing problem due to the almost exclusively use of chemical insecticides to manage mosquito pests in many territories during decades. Resistance may develop due to changes in enzyme systems of mosquitoes, resulting in more rapid detoxification or sequestration of the insecticide, or even due to mutations in the target site preventing the insecticide-target interaction (Hemingway et al., 2004). In recent years, the use of toxins derived from Bacillus species bacteria has been deeply established as one of the best tools to reduce mosquito larval populations. Although in some phenomena of resistance on mosquitoes have been described in products derived from Bacillus under special conditions (Paris et al., 2011), these issues must be further analyzed because there are hundreds of researches that never have been able to demonstrate the existence of resistance processes in these bacterial larvicides. In any case, to try to minimize possible appearance of resistance problems, major emphasis must be applied on the use of natural plant-based products as larvicides which can be a safe alternate to chemical or bacterial insecticides. At respect, more than 2000 plants species have been known to produce chemical factors and metabolites of value in pest control programs, and among these plants, products of some 344 species have been reported to have a variety of activities against mosquitoes (Sukumar et al., 1991). Unfortunately, very few plant products have been developed for controlling mosquitoes, despite some phytochemicals are able to act against mosquitoes as growth regulators, repellents, and ovipositional deterrent (Amer and Mehlhorn, 2006; Rajkumar and Jebanesan, 2007). Finally I would like to acknowledge Eastep and colleagues for his valuable contribution to classical strategies of fight against mosquito-borne diseases and also highlight that manuscript of Eastep et al. (2012) is one of the articles selected in the Research Topic titled “Global change and human vulnerability to vector-borne diseases” published by Frontiers in Physiology-Systems Biology which includes many researches related with the use of other natural larvicides against mosquitoes (Kumar et al., 2012) or the impact of climate trends on vector-borne pathogen transmission (Estrada-Pena et al., 2012), among other themes. This Research Topic could be visited through next link: http://www.frontiersin.org/Systems_Biology/researchtopics/GLOBAL_CHANGE_AND_HUMAN_VULNER/323.

American cockroach control assays in the municipal sewerage system of Valencia (Spain)

ABSTRACT Several insecticides (including different active substances and formulations) were applied to sewer shafts to control Periplaneta americana (LINNAEUS, 1758) populations in Valencia (eastern Spain). Results show that the best products for cockroach control were the paints (with and without insecticide), which provided an optimal reduction of P. americana populations for up to three months (P < 0.001). Therefore, it is important to note that the reduction of cockroach populations as well as the persistence of the insecticide effect in sewers was similar in both types of paints. A product combining two pyrethroids (Tetramethrin and Alfacipermetrin) and piperonyl butoxide also gave excellent results with cockroach control during one month. Two organophosphate insecticides (Clorpyrifos and Diazinon) significantly reduced cockroaches for only one week. Finally, our work indicates that the Insect Growth Regulators (IGRs) we tested are not recommendable active substances for the control of P. americana in sewers.