Climatic Factors Driving Invasion of the Tiger Mosquito (Aedes albopictus) into New Areas of Trentino, Northern Italy

Background:The tiger mosquito (Aedes albopictus), vector of several emerging diseases, is expanding into more northerly latitudes as well as into higher altitudes in northern Italy. Changes in the pattern of distribution of the tiger mosquito may affect the potential spread of infectious diseases transmitted by this species in Europe. Therefore, predicting suitable areas of future establishment and spread is essential for planning early prevention and control strategies.Methodology/Principal Findings:To identify the areas currently most suitable for the occurrence of the tiger mosquito in the Province of Trento, we combined field entomological observations with analyses of satellite temperature data (MODIS Land Surface Temperature: LST) and human population data. We determine threshold conditions for the survival of overwintering eggs and for adult survival using both January mean temperatures and annual mean temperatures. We show that the 0°C LST threshold for January mean temperatures and the 11°C threshold for annual mean temperatures provide the best predictors for identifying the areas that could potentially support populations of this mosquito. In fact, human population density and distance to human settlements appear to be less important variables affecting mosquito distribution in this area. Finally, we evaluated the future establishment and spread of this species in relation to predicted climate warming by considering the A2 scenario for 2050 statistically downscaled at regional level in which winter and annual temperatures increase by 1.5 and 1°C, respectively.Conclusions/Significance:MODIS satellite LST data are useful for accurately predicting potential areas of tiger mosquito distribution and for revealing the range limits of this species in mountainous areas, predictions which could be extended to an European scale. We show that the observed trend of increasing temperatures due to climate change could facilitate further invasion of Ae. albopictus into new areas. © 2011 Roiz et al.Peer Reviewe

Are Aedes albopictus or other mosquito species from northern Italy competent to sustain new arboviral outbreaks?

International audienceThe Asian tiger mosquito Aedes albopictus (Skuse) (Diptera: Culicidae), native to Southeast Asia, has extended its geographical distribution to invade new temperate and tropical regions. This species was introduced in 1990 to Italy and has since become the main pest in urban settings. It was incriminated as a principal vector in the first European outbreak of chikungunya virus (CHIKV) in the province of Ravenna (Italy) in 2007. This outbreak was associated with CHIKV E1-226V, efficiently transmitted by Ae. albopictus. The occurrence of this outbreak in a temperate country led us to estimate the potential of Ae. albopictus to transmit CHIKV and dengue virus (DENV), and to determine the susceptibility to CHIKV of other mosquito species collected in northern Italy. Experimental infections showed that Ae. albopictus exhibited high disseminated infection rates for CHIKV (75.0% in Alessandria; 90.3% in San Lazzaro) and low disseminated infection rates for DENV-2 (14.3% in San Lazzaro; 38.5% in Alessandria). Moreover, Ae. albopictus was able to attain a high level of viral replication, with CHIKV detectable in the salivary glands at day 2 after infection. In addition, the other three mosquito species, Anopheles maculipennis Meigen, Aedes vexans vexans (Meigen) and Culex pipiens L., showed variable susceptibilities to infection with CHIKV, of 0%, 7.7% and 0-33%, respectively. This information on vector competence is crucial in assessing the risk for an outbreak of CHIKV or DENV in Italy

Evaluation of lotions of botanical-based repellents against aedes aegypti (Diptera: Culicidae)

Thirteen botanical product repellent compounds such as 2-undecanone, capric, lauric, coconut fatty acids (and their methyl ester derivatives), and catnip oil were formulated in either Coppertone or Aroma Land lotions and evaluated against laboratory-reared Aedes aegypti L. (Diptera: Culicidae) mosquitoes. These formulations contained 7-15 wt/wt of the botanical repellent as the major active ingredient either pure or as mixtures. USDA standard repellent test cages were used to determine the complete protection time (CPT) of the different formulated repellents. Two of the evaluated formulations, a 7% capric acid in Coppertone (CPT 2.7 ± 0.6 h) and 7% coconut fatty acids containing carrylic acid, capric acid, and lauric acid in Coppertone (CPT 2.3 ± 2.0 h), provided strong repellency against mosquitoes up to 3 h, which was equivalent to the (N,N-diethyl-m-toluamide) DEET control (CPT 2.7 ± 0.6 h). This work suggests future potential for these botanical product-based repellents as alternatives to commercial DEET-containing products

Chikungunya Virus and Zika Virus in Europe

Chikungunya fever epidemics display secular, cyclical, and seasonal trends. These epidemics are characterized by explosive outbreaks inter- spersed by periods of disappearance ranging from several years to a few decades. Several mechanisms play a role: the human and the mosquito vector susceptibility to the virus; conditions facilitating mosquito breed- ing (resulting in a high vector density), ability of the vector to efficiently transmit the virus. There are historical accounts of epidemics of fever, arthralgias/arthritis, and rash, resembling what is now called \u201cChikungunya fever\u201d dating back to 1824 from India and elsewhere (Kaur et al., 2008). Chikungunya virus (CHIKV) was firstly detected in Central/East Africa, where it is maintained in a sylvatic transmission cycle between nonhuman primates, small mammals (e.g., bats and monkeys) and Aedes mosquitoes . Urban chikungunya fever outbreaks are initiated by spillover infection of humans from enzootic African transmission cycles. The first identified outbreak of Chikungunya was reported from July 1952 to March 1953 in Tanzania. Since its discovery, numerous Chikungunya re-emergences have been documented. Currently, the Chikungunya virus has been identified in over 60 countries. The risk of importation of CHIKV into new areas is ever present because of the high attack rates associated with the recurring epidemics, the high levels of vi- remia in infected humans, and the worldwide distribution of the vectors responsible for transmitting CHIKV. E1-A226V and E2-L210Q mutations have been found to cause a dramatic increase in the infectivity of CHIKV, and the transmission of CHIKV has spread to Europe and the Americas because of the widespread distribution of the vectors Aedes aegypti and Ae. albopictu