Modeling and updating the occurrence of Aedes aegypti in its southern limit of distribution in South America.

Aedes aegypti is the main vector of arboviruses in the world. This mosquito species is distributed from tropical to temperate regions. In Argentina, it has been reported in 20 out of 23 provinces and reaches its southernmost distribution in the world. Its distribution and persistence are affected by meteorological, demographic and environmental factors, such as temperature, precipitation, and population. The aim of this study was to update and model the occurrence of Aedes aegypti in its southern limit of distribution in Argentina. To this end, a total of 37 sites were inspected in La Pampa and Río Negro provinces. Generalized Linear Models were used to explain the occurrence of Aedes aegypti based on meteorological, environmental and demographic variables. Aedes aegypti was found in 11 cities of La Pampa province where it had not been previously reported, but was not found in any of the cities evaluated in Río Negro province. The averaged model explaining the occurrence of Aedes aegypti included the minimum temperature, precipitation and interactions between maximum temperature and precipitation as explanatory variables. Although precipitation was statistically significant, other factors such as minimum temperature are also important in modeling the occurrence of Aedes aegypti in its southernmost distribution limit.

Winter survival of Aedes aegypti (Diptera: Culicidae) eggs at its southern limit distribution.

Aedes aegypti (L.) (Diptera: Culicidae) survives in the egg stage under unfavorable environmental conditions. In this study, we assessed the survival of Ae. aegypti eggs under natural winter conditions as an overwintering mechanism. To address this, field collected eggs (from Buenos Aires city) were exposed for three months during the winter season in three sites of Santa Rosa and General Acha (La Pampa province, Argentina). Eggs survival and hatching response were analyzed considering two factors (site of exposure and time of oviposition). Of the 1397 analyzed eggs, 936 (67%) were viable at the end of the study. Egg survival showed to be high in all sites (between 53% and 84%), except in one site of Santa Rosa. Also, eggs survival was higher in eggs laid in May (94%) (late-fall) as compared to those laid in March (61%) and April (56%) (early- and mid-fall respectively). Eggs hatching response was only affected by the time of oviposition, being lower for eggs laid in May (33%) as compared to March (38%) and April (50%). These results provide information regarding the winter resistance of Ae. aegypti at the limit of its distribution in temperate regions. Given the high percentages of survival found in this study, we consider that the low winter temperatures would not be a limitation for its establishment in southern areas.

Global Potential Distribution of the South American Cutworm Pest Agrotis robusta (Lepidoptera: Noctuidae).

Invasive pest species can represent significant losses to the agricultural economy of a country. Assessing the potential distribution of known pest species could be an important tool to evaluate possible invasive threats globally. Agrotis robusta (Blanchard) is an endemic species of temperate areas of South America considered an important pest of seedlings of sunflower, dry bean, and potatoes. The polyphagous habit of A. robusta, along with its regional importance and history of misidentifications, makes it a species of concern for other regions of the world. In this work, we assessed the potential distribution of A. robusta with Maxent based on occurrence data and variables related to climate and soil. The bioclimate profile of the species showed a marked seasonality and medium average monthly temperature, coinciding with the temperate climate of the Köppen-Geiger classification. Other important variables related to the species distribution included average solar radiation and soil pH. Suitable conditions were identified in North America, Central America, Europe, Southern Africa, Asia, and Australia. High suitable places overlapped with some of the most important countries of production of host crops of A. robusta. Our conclusions highlight the importance of taking this species into account when importing goods from countries with the presence of A. robusta, especially for countries that are important producers of host crops.

The austral-most record of the genus Haemagogus Williston (Diptera: Culicidae).

INTRODUCTION: The genus Haemagogus Williston is restricted to Central America and North and middle of South America and it includes numerous species of yellow fever virus vectors. METHODS: Adult female and larvae mosquitoes were collected using hand aspirators and dipper and pipette, respectively. RESULTS: The first record of a species of Haemagogus and particularly of Haemagogus spegazzinii was from La Pampa, Argentina. With this registry, the number of species found in La Pampa province rises to 18. CONCLUSIONS: New information on breeding sites for the species and implications of this new record suggest a possible extension of distribution in the near future.

The austral-most record of the genus Haemagogus Williston (Diptera: Culicidae)

Abstract INTRODUCTION: The genus Haemagogus Williston is restricted to Central America and North and middle of South America and it includes numerous species of yellow fever virus vectors. METHODS: Adult female and larvae mosquitoes were collected using hand aspirators and dipper and pipette, respectively. RESULTS: The first record of a species of Haemagogus and particularly of Haemagogus spegazzinii was from La Pampa, Argentina. With this registry, the number of species found in La Pampa province rises to 18. CONCLUSIONS: New information on breeding sites for the species and implications of this new record suggest a possible extension of distribution in the near future.